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Your diet is one of the first places to start if you’re looking to manage your health and weight. Focusing on whole foods from plant sources can reduce body weight, blood pressure and risk of heart disease, cancer and diabetes — and it can make your environmental impact more sustainable.

But how do we embrace plants in our diets if we’re so accustomed to including meat and dairy as primary nutrition sources?

We spoke with Dr. Reshma Shah, a physician, plant-based eating advocate, co-author of “Nourish: The Definitive Plant-Based Nutrition Guide for Families” and Stanford Healthy Living instructor, about simple ways to incorporate more plants into your diet and the benefits this can provide for both you and the planet.  

Focus on whole, minimally processed foods.

People use many different terms to describe a plant-based diet, including vegetarian, lacto-ovo vegetarian, pescatarian, and flexitarian to name a few. The most restrictive is veganism, which  excludes all animal products, including meat, eggs and dairy. 

While there are health benefits to adopting a vegan diet, highly processed foods with little to no nutritional value, like Oreos or French fries, could still be a legitimate part of a vegan diet.

In contrast, a whole-foods, plant-based (WFPB) diet: 

• Emphasizes whole, minimally processed foods
• Limits or avoids animal products
• Focuses on plant nutrients from vegetables, fruits, whole grains, legumes, seeds and nuts 
• Limits refined foods like added sugar, white flour and processed oils 

Recommendations from organizations including the U.S. Dietary Guidelines for Americans, World Health Organization, American Diabetes Association and American Cancer Society tout the benefits of plant-based whole foods and caution against high amounts of red and processed meats, saturated fats, highly refined foods and added sugar. 

The vast majority of what nutritional experts are saying reflects the mantra made famous by Michael Pollen in his book “The Omnivore’s Dilemma” — eat food, mostly plants, not too much . 

Eating a plant-based diet helps the environment.

According to a report by the U.S. Food and Agriculture Organization, “The meat industry has a marked impact on a general global scale on water, soils, extinction of plants and animals, and consumption of natural resources, and it has a strong impact on global warming.” 

The meat and dairy industries alone use one third of the Earth’s fresh water , with a single quarter-pound hamburger patty requiring 460 gallons of water — the equivalent of almost 30 showers — to produce.

Reducing your meat and dairy consumption, even by a little, can have big impacts. If everyone in the U.S. ate no meat or cheese just one day a week, it would have the same environmental impact as taking 7.6 million cars off the road.

Plant-based diets prevent animal cruelty. 

Ninety-four percent of Americans agree that animals raised for food deserve to be free from abuse and cruelty , yet 99% of those animals are raised in factory farms, many suffering unspeakable conditions . 

If you would like to lessen your meat and dairy consumption due to animal welfare concerns but aren’t ready to eliminate all animal products from your diet, then you can start by taking small steps, like going meatless one day a week or switching to soy, almond or oat milk. Shah admits that initially she was not ready to give up animal products entirely. 

“I think it is a process and recommend that people go at the pace that feels comfortable for them.” 

Plant-based diets include all nutrients — even protein.

According to the American Dietetic Association, “appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, and for athletes.”

Shah says that there are a few key nutrients that strict vegans and vegetarians should keep in mind, including B12, iron, calcium, iodine, omega-3 fatty acids and vitamin D, but all of these can be obtained through plant-based foods, including fortified plant-based milks, fresh fruits and vegetables or supplemental vitamins, if needed. 

“I think the number one concern for people is that they won’t be able to get enough protein eating a plant-based diet. I also think that people widely overestimate the amount of protein they need.”

All plant foods contain the nine essential amino acids required to make up the proteins you need, and many vegetarian foods like soy, beans, nuts, seeds and non-dairy milk products have comparable amounts of protein to animal foods. 

“Ninety-seven percent of Americans meet their daily protein requirements, but only 4% of Americans meet their daily fiber requirements . I’ve never treated a patient for protein deficiency. If you eat a wide variety of foods and eat enough calories, protein should not be a concern.”

Savor the flavor of plant-based foods. 

Adopting a plant-based diet does not mean subsisting on boring, tasteless food. Shah enjoys incorporating flavorful, varied dishes from around the world, including Ethiopia, Thailand and her native India. 

To get started on your plant-forward journey:

• Start small: Start with adding a “Meatless Monday” to your meal plan and investigate one simple and delicious recipe to try each week. Once you have identified a few favorites, you can add them to your rotation and maybe go meatless one or two days a week. You can learn a few easy techniques to incorporate in many dishes, like roasting vegetables or blending quick and easy soups. 
• Change your plate proportions: Instead of giving up your meat-based protein completely, try to reduce the space it takes on your plate. Instead of a quarter-pound sirloin steak or a full serving of roasted chicken, try a vegetable-heavy stir-fry with a few slices of beef or a salad with chicken. Once your palate and mindset have adjusted to the smaller quantity of meat, try replacing it occasionally with plant-based proteins like tofu, seitan or beans.  
• Be prepared when dining out: If possible, try to examine the restaurant menu ahead of your meal, so you’ll arrive with a plan of what you can eat. Ask for the vegan options and don’t be afraid to request substitutions or omissions for your dish. Fortunately, with more people choosing a vegetarian lifestyle, many restaurants now provide tasty, meat-free options to their customers. 
• Share a dish: Bring a dish to share at a party or potluck; this will lessen your worries about food options. Let your host know ahead of time that you are planning on bringing a dish or, if that is not possible, be upfront and find out if any modifications can be made to accommodate your preferences. Often a simple solution can be found with a little advanced planning.
• Accommodate family members: It can be tricky when one family member is ready to commit to a new diet and lifestyle while others are not. Shah recommends approaching this situation compassionately and allowing for flexibility, if possible. Hopefully your family will be willing to support you even if they are not ready to make the same commitments. Communication is key, and Shah says that the conversation is over the minute someone feels judged, so try to look for points of compromise to reach an amicable solution. 
• Feeling satisfied: A diet of nothing but lettuce and vegetables will leave you feeling hungry and unfulfilled. Be sure to bulk up your meals with filling, fiber-rich whole grains, plant-based proteins and healthy fats. Plant-based meat substitutes like Beyond Beef, seitan and veggie burgers can also be a satisfying choice when you are craving your favorite meat-based comfort food.

Remember that small, consistent changes can add up to big benefits for your health and the planet. Treat yourself and others with compassion as you embrace this new lifestyle, and take time to enjoy the different flavors and textures you discover in your journey.

“It is a really delicious, healthful, sustainable and compassionate way of eating. It doesn’t have to be perfect. Just start simply, do what feels comfortable for you and your family, and don’t forget to celebrate the joy of eating and connection around food.” 

Dr. Reshma Shah will be teaching a plant-based online cooking class with Healthy Living this summer on Tuesday, July 13, from 4:00 – 5:30 p.m.

• https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6518108/
• https://www.sciencedirect.com/science/article/pii/S2212371713000024 
•  https://www.portland.gov/water/water-efficiency-programs/save-water-home 
•   https://water.usgs.gov/edu/activity-watercontent.php  
• https://www.ewg.org/meateatersguide/a-meat-eaters-guide-to-climate-change-health-what-you-eat-matters/reducing-your-footprint/)  
• https://www.aspca.org/about-us/press-releases/aspca-research-shows-americans-overwhelmingly-support-investigations-expose 
•  https://www.sentienceinstitute.org/us-factory-farming-estimates
•  https://pubmed.ncbi.nlm.nih.gov/19562864/ 
•   https://www.ars.usda.gov/ARSUserFiles/8040053 0/pdf/0102/usualintaketables2001-02.pdf

Healthy plant-based diets better for the environment than less healthy plant-based diets

For immediate release: November 10, 2022

Boston, MA – Healthier plant-based dietary patterns were associated with better environmental health , while less healthy plant-based dietary patterns, which are higher in foods like refined grains and sugar-sweetened beverages , required more cropland and fertilizer, according to a new study led by researchers at Harvard T.H. Chan School of Health and Brigham and Women’s Hospital. The findings also showed that red and processed meat had the highest environmental impact out of all food groups in participants’ diets, producing the greatest share of greenhouse gas emissions and requiring the most irrigation water, cropland, and fertilizer. 

“The differences between plant-based diets was surprising because they’re often portrayed as universally healthy and good for the environment, but it’s more nuanced than that,” said Aviva Musicus , postdoctoral research fellow in the Department of Nutrition at Harvard Chan School and corresponding author of the study. “To be clear, we’re not asserting that less healthy plant-based diets are worse for the environment than animal-based diets. However, our findings show that plant-based diets can have different health and environmental impacts.” 

The study, which is one of the first to look simultaneously at the health and environmental impacts of  various plant-based diets, was published in the November 2022 edition of The Lancet Planetary Health.

Previous research has documented that different types of plant-based diets have various health effects. For example, plant-based diets higher in  whole grains, fruits, vegetables , nuts , legumes, vegetable oils , and tea/ coffee  are associated with reduced chronic disease risk, while plant-based diets high in  fruit juices, sugar-sweetened beverages, refined grains, potatoes, and sweets/desserts are  associated with an increased risk of chronic disease. Yet little research has been conducted to determine the environmental impacts, such as greenhouse gas emissions, use of high-quality cropland, nitrogen from fertilizer, and irrigation water, of these dietary approaches. 

Using data from t he Nurses’ Health Study II,  the researchers analyzed the food intakes of more than 65,000 qualifying participants, and examined their diets’ associations with health outcomes, including relative risks of cardiovascular disease , and with environmental impacts. To differentiate plant-based dietary patterns, the researchers characterized participants’ diets using various dietary indices, including the Healthy and Unhealthy Plant-based Diet Indices. Higher scores on the unhealthy plant-based diet index indicated higher consumption of refined grains, sugary drinks, fruit juice, potatoes, and sweets/desserts; while higher scores on the healthy plant-based diet index indicated higher consumption of vegetables, fruits, whole grains, nuts, legumes, vegetable oils, and tea/coffee.  

Participants who consumed healthy plant-based diets  had lower cardiovascular disease risk, and those diets had lower greenhouse gas emissions and use of cropland, irrigation water, and nitrogenous fertilizer than diets that were higher in unhealthy plant-based and animal-based foods. Participants who ate unhealthy plant-based diets experienced a higher risk of cardiovascular disease, and their diets required more cropland and fertilizer than diets that were higher in healthy plant-based and animal foods. The findings also reinforced earlier studies showing that diets higher in animal-based foods, especially red and processed meat, have greater adverse environmental impacts than plant-based diets.    

“ Because human health ultimately depends upon planetary health , future U.S. dietary guidelines should include nuanced consideration of environmental sustainability and recognize that not all plant-based diets confer the same health and environmental benefits,”  said Daniel Wang , assistant professor in the Department of Nutrition at Harvard Chan School, the Channing Division of Network Medicine at Brigham and Women’s Hospital and Harvard Medical School, and co-author of the study.  

This study was supported by the National Institutes of Health (NIH grants U01 CA176726, UM1 CA186107, HL35464, and 2T32CA057711).  

“Health and environmental impacts of plant-rich dietary patterns: A U.S. prospective cohort study,” Aviva A. Musicus, Dong D. Wang, Marie Janiszewski, Gidon Eshel, Stacy A. Blondin,  Walter Willett, Meir J. Stampfer, The Lancet Planetary Health, online November 2022, doi:10.1016/S2542-5196(22)00243-1. 

For more information:

Harvard T.H. Chan School of Public Health Todd Datz [email protected] 617.432.8413

Brigham and Women’s Hospital Serena Bronda [email protected] 867.869.7828

photo: iStock

Harvard T.H. Chan School of Public Health  brings together dedicated experts from many disciplines to educate new generations of global health leaders and produce powerful ideas that improve the lives and health of people everywhere. As a community of leading scientists, educators, and students, we work together to take innovative ideas from the laboratory to people’s lives—not only making scientific breakthroughs, but also working to change individual behaviors, public policies, and health care practices. Each year, more than 400 faculty members at Harvard Chan School teach 1,000-plus full-time students from around the world and train thousands more through online and executive education courses. Founded in 1913 as the Harvard-MIT School of Health Officers, the School is recognized as America’s oldest professional training program in public health. 

Brigham and Women’s Hospital is a founding member of Mass General Brigham and a teaching affiliate of Harvard Medical School. With nearly 1,000 inpatient beds, approximately 50,000 inpatient stays, and over 2.6 million outpatient encounters annually, clinicians across the Brigham provide compassionate, high-quality care in virtually every medical and surgical specialty to patients locally, regionally, nationally and around the world. An international leader in basic, clinical, and translational research, Brigham and Women’s Hospital has nearly 5,000 scientists, including physician-investigators, renowned biomedical researchers and faculty supported by nearly $750 million in funding. The Brigham’s medical preeminence and service to the community dates to 1832, with the opening of the Boston Lying In, one of the nation’s first maternity hospitals designed to care for women unable to afford in-home medical care. Its merger with the Free Hospital for Women resulted in the Boston Hospital for Women in 1966. In 1980, the Boston Hospital for Women, the Peter Bent Brigham Hospital and the Robert Breck Brigham Hospital officially merged to become Brigham and Women’s Hospital. With nearly 21,000 employees across the Brigham family – including the Brigham and Women’s Physicians Organization and Brigham and Women’s Faulkner Hospital – that rich history is the foundation for our commitment to providing superb care for some of the most complex cases, pursuing breakthroughs in biomedical research, training the next generation of health care providers, and serving the local and global community. 

Ready to start planning your care?  Call us at 800-525-2225 to make an appointment.

Research Shows Plant-Based Diets Are Better Than Ketogenic Diets for Cancer Risk and Long-Term Health

Monday, July 25, 2022

MSK experts Dr. Urvi Shah (left) and Dr. Neil Iyengar reviewed the research for whole food plant based diets and ketogenic diets. They found that plant based diets are better than keto diets at reducing cancer risk and helping people live healthier lives after cancer treatment.

People have sought answers about the relationship between nutrition and health throughout history. In the past few decades, scientific research has uncovered important insights about our diets and cancer, including how food can affect our risk of developing the disease, the treatment of cancer, and living well after cancer.

Experts at Memorial Sloan Kettering Cancer Center (MSK) are at the forefront of this research. Hematologic oncologist Urvi Shah cares for people with plasma cell disorders, including multiple myeloma . Medical oncologist Neil Iyengar treats people with breast cancer . Both conduct research aimed at understanding the interplay between nutrition and cancer.

Drs. Shah and Iyengar recently conducted a review of studies that examine the relationship between diet and cancer. They focused on two of the most popular diets — a whole foods, plant-based diet and the keto, or ketogenic, diet.

Their review was published in JAMA Oncology in July 2022 and offers important new insights into which of these two very different approaches are best for people concerned with reducing their cancer risk and improving their health after treatment.

Why did you focus on plant-based and keto diets? 

Dr. Shah: One reason is many of our patients ask about these two diets. Patients sometimes question: “Are sugars bad? Do sugars cause the cancer to get worse?” That’s why a keto diet may appeal to some patients — because it’s considered low-carb, so they think they are eliminating sugars, which may reduce cancer risk. Although this is not entirely true, and while we can all agree that refined carbohydrates are bad, consumption of whole grains have been associated with a reduced cancer risk.

We also get many questions about a plant-based diet, as there is more awareness of the health benefits of plant foods, especially the importance of fiber, which is only derived from plants. There is now a large and growing body of scientific research about these two diets. The concepts behind these diets are diametrically opposite. So comparing the research to understand differences about both of them is helpful.

Dr. Iyengar: There is growing evidence that weight loss is helpful for reducing cancer risk, particularly for obese and older people, including the postmenopausal age group. Both keto and plant-based diets have proven effective for weight loss. However, there is less available data to answer whether the benefits of these diets extend to cancer. Most of the available data support a whole foods, plant-based diet over a ketogenic diet for reducing the risk of cancer. After a cancer diagnosis, a plant-based diet still appears to be superior.

However, some studies in mice show that the keto diet is useful in very specific tumor types, such as a specific type of breast cancer with mutations in the PIK3CA gene. Ongoing research is investigating whether this is true for humans with this type of breast cancer. It is important to note that the keto diet made one type of blood cancer worse in the mouse study, so it is important to wait for data from the human studies before we can recommend the keto diet to people diagnosed with cancer.

What is a keto diet?

Dr. Shah: The aim is to force the body into using a different type of fuel, called ketone bodies, rather than relying on sugar that comes from carbohydrates like grains and fruits. This usually requires getting a very large percentage of calories from high-fat foods, including meat, dairy, fish, oils, and eggs.

Many diets that claim to be ketogenic are actually just low-carb, however. They don’t really force the body into the state of ketosis, where the body breaks down protein and fat for energy. That can make it challenging to compare keto-style diets for their beneficial effects, since they vary quite a bit.

Dr. Iyengar: For some cancers — including breast cancer — it’s also important to note that higher fat consumption has been associated with poorer long-term outcomes. And some diets claiming to be keto allow for fats from highly processed foods, which isn’t great. There are many so-called keto foods available at grocery stores, but some could actually be harmful if the fat content is higher than it should be.

For patients diagnosed with breast cancer, MSK has a keto clinical trial called TIFA that is very specifically controlled to avoid those pitfalls. For instance, we deliver preprepared meals to patients so the mix of nutrients is appropriate. We encourage patients to look for well-designed trials like the TIFA trial if they are interested in ketogenic diets.

Learn more about a keto diet

What is a plant-based diet?

Dr. Shah: When we talk about a whole foods, plant-based diet, we mean the majority (at least 80% to 90%) of the food should be unprocessed plant-based foods — things like legumes, fruits, vegetables, seeds, whole grains, and nuts. Some people may end up eating minimal amounts of processed plant foods or animal-based foods like dairy or meat occasionally, but not on a regular basis.

Learn more about plant-based diets

What’s the difference between plant-based, vegetarian, and vegan diets?

Dr. Shah: I tell patients that vegan means zero animal products and is grounded in ethical or environmental or health reasons for a person who has decided very clearly what they want. A vegetarian diet may have similar reasons but allows dairy or eggs in varying proportions. A whole foods, plant-based diet can be similar to a Mediterranean diet or other diets that include eating meat rarely. Again, the majority (90%) of foods should be whole plant-based foods.

Dr. Iyengar: We don’t have strong enough evidence to conclude that vegan eating is superior to a semi-vegetarian diet for reducing the risk of cancer or cancer recurrence. MSK and other centers are running trials that will help address this question.

Which diet did your review find was better at reducing the risk of cancer — a plant-based diet or keto?

Dr. Shah: Our review of the evidence supports a plant-based diet for reducing cancer risk compared with a ketogenic diet. That conclusion is particularly apparent when you look at big populations, such as three large studies conducted in the U.S., U.K., and France. All three found that people eating more plants and less animal protein had less cancer overall. That’s consistent with other large studies and included in the guidelines by the American Institute of Cancer Research and American Cancer Society, which all recommend diets that incorporate high amounts of plant-based food.

Dr. Iyengar: There are many biologic processes in the body that are impacted by diet and energy balance in general. Many of these processes are involved in the growth of cancer, such as obesity and inflammation , hormones, insulin, the microbiome, and more. We examine several of these processes in our review. The bottom line for people looking to reduce their risk of cancer is that the current evidence supports a plant-based diet over a keto diet.

Research also shows that broad dietary patterns that people can stick to — like a plant-based diet — are generally better in the long-term than highly specific interventions like keto diets.

Which diet was better during treatment?

Dr. Iyengar: Currently, there is no evidence to suggest that a specific diet by itself can treat cancer. There is preliminary evidence to suggest that certain dietary patterns can help make some cancer treatments work better or reduce side effects. For instance, studies have shown that plant-based diets can help with some of the gastrointestinal toxicity from chemotherapy and joint pain from hormonal treatments for breast cancer.

There is also some evidence that the keto diet could reduce certain side effects, such as high blood sugar levels, from specific cancer treatments.

Of course, it’s important for people being treated for cancer to check with their oncologist about any specific changes to their diet.

Which diet was better for healthy living after treatment?

Dr. Iyengar: The majority of breast cancer is curable, but there can be long-term metabolic disorders from cancer treatment. In fact, many people treated for cancer are at increased risk for diabetes, obesity, and heart disease.

We know that a plant-based diet can help reduce the risk of these metabolic disorders, which is why I typically recommend this diet to my patients — we don’t want to just cure a person’s cancer; we want to also improve health overall.

Dr. Shah: It’s important that people — especially those facing cancer — think about the broad conclusions and common themes that emerge from dietary studies. For example, don’t focus too much on specifics like trying to avoid all sugar or carbohydrates; rather, cut out refined sugars and incorporate whole grains that are known to have health benefits. Trying to make changes with every study one comes across can drive a person crazy, especially if it says opposing things to the majority of data and cause a negative relationship with food.

Instead, concentrate on a healthy, plant-forward eating pattern that can be sustained, make gradual changes, and stick to it.

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• Published: 03 June 2021

A brief review of the science behind the design of healthy and sustainable plant-based foods

• David Julian McClements   ORCID: orcid.org/0000-0002-9016-1291 1 &
• Lutz Grossmann   ORCID: orcid.org/0000-0001-9685-6900 1  

npj Science of Food volume  5 , Article number:  17 ( 2021 ) Cite this article

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• Gels and hydrogels

People are being encouraged to consume more plant-based foods to reduce the negative impacts of the modern food supply on human and global health. The food industry is therefore creating a new generation of plant-based products to meet this demand, including meat, fish, egg, milk, cheese, and yogurt analogs. The main challenge in this area is to simulate the desirable appearance, texture, flavor, mouthfeel, nutrition, and functionality of these products using healthy, affordable, and sustainable plant-derived ingredients, such as lipids, proteins, and carbohydrates. The molecular and physicochemical properties of plant-derived ingredients are very different from those of animal-derived ones. It is therefore critical to understand the fundamental attributes of plant-derived ingredients and how they can be assembled into structures resembling those found in animal products. This short review provides an overview of the current status of the scientific understanding of plant-based foods and highlights areas where further research is required. In particular, it focuses on the chemical, physical, and functional properties of plant ingredients; the processing operations that can be used to convert these ingredients into food products; and the science behind the creation of some common plant-based foods, namely meat, egg, and milk analogs.

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Introduction.

The modern food and agricultural industries have produced a plentiful supply of safe, affordable, convenient, and tasty foods, contributing to a significant reduction in world hunger and malnutrition over the past century. But current food production practices are also linked to the high prevalence of some chronic diseases, as well as to appreciable environmental damage 1 , 2 , 3 . A higher quantity and enhanced quality of food are required to feed a global population that is growing and becoming wealthier 3 . The production of large quantities of animal products, such as meat, fish, egg, milk, and their derivatives, has been proposed to be a major factor contributing to the negative impact of the modern food supply on global environmental sustainability 1 . Rearing livestock for food typically leads to more pollution, as well as greater greenhouse gas emissions, water use, land use, and loss of biodiversity than growing plants directly for consumption 4 . It should be noted, however, that there are areas unsuitable for the production of agricultural crops that are suitable for the raising of animals as foods. Moreover, some studies have shown that switching to a more plant-based diet may result in a slight increase in overall water use and only a modest decrease in overall cropland use 4 . However, many people have ethical concerns about confining and slaughtering animals, which is motivating them to switch to a more plant-based diet 5 , 6 . Moreover, many consumers believe a plant-based diet is healthier than an animal-based one, which is driving changes in their eating behaviors 6 , but it is important to note that a plant-based diet is not necessarily better than an omnivore diet from a nutritional perspective 7 . Animal foods, such as meat, milk, and egg, often contain micronutrients that are lacking from an entirely plant-based diet, such as vitamin D, calcium, and zinc. For this reason, plant-based foods often need to be fortified with these micronutrients.

As a result of these environmental, ethical, and health concerns, the plant-based food sector is expanding rapidly to meet consumer demand 8 . This sector includes a range of products created as alternatives to those normally produced from animals, including milk, meat, fish, eggs, and products where they are used as ingredients (Table 1 ). Each product category is expected to have its own unique physical, functional, nutritional, and sensory attributes. The food industry must therefore identify appropriate combinations of ingredients and manufacturing operations to economically create these attributes in plant-based foods on a large scale. As a result, they need knowledge of the molecular and physicochemical properties of plant-derived ingredients, how they can be assembled into structures that mimic those found in animal products, and how these structures influence the physicochemical and organoleptic properties of the end product. Ideally, these plant-based products should also be designed to be healthy, which involves controlling their nutrient profile, digestibility, and bioavailability. In the case of plant proteins, it is important to ensure that they are able to provide the full complement of essential amino acids and that they are digestible 9 . A well-balanced essential amino acid profile can often be achieved by consuming a mixture of plant proteins from different sources, such as grains and legumes.

Plant-based ingredients

Initially, it is important to identify an appropriate blend of plant-derived ingredients to produce a specific plant-based food, such as a meat, fish, egg, or milk analog. These ingredients may be isolated nutrients (such as proteins, carbohydrates, fats, vitamins, or minerals) or complex whole materials (such as beans, peas, rice, wheat, mushrooms, etc.). These ingredients have compositions, structures, and physicochemical properties that are very different from those found in animal products. One of the major challenges is therefore to assemble these ingredients into animal product analogs. Sometimes plant-derived ingredients can be used as-is (e.g., mushrooms), but in other cases, they may have to be dissembled into specific structural elements before being reassembled into animal product analogs (e.g., soy proteins). A brief outline of some of the main plant-derived ingredients used to form plant-based foods is given here.

Plant-based proteins

Plant proteins are commonly used in plant-based foods because of their versatile functional attributes, such as their ability to thicken, gel, emulsify, foam, and hold fluids 9 , 10 . In addition, they are an important source of essential amino acids. These proteins can be derived from various botanical sources, including soybeans, peas, faba beans, mung beans, lentils, algae, and microalgae, each with its own unique characteristics (Table 2 ). Most plant proteins have globular structures and are often present as complex multimers consisting of numerous different types of protein held together by physical and/or chemical bonds (Fig. 1 ). The functionality of these proteins depends on their biological origin, as well as any changes in their association and native states during isolation and purification. A major challenge in the plant-based food sector is the lack of plant proteins with consistent functional attributes. In the future, more research is required to identify appropriate botanical sources and isolation procedures for producing reliable functional ingredients. Another major challenge is to coax plant proteins into structural organizations that mimic those found in animal products (Fig. 2 ), thereby leading to similar physicochemical attributes.

The 3D view is for the soy glycinin hexamer, which is from the Protein Data Bank 1FXZ: Adachi, M., Takenaka, Y., Gidamis, A. B., Mikami, B., Utsumi, S. Crystal structure of soybean proglycinin A1aB1b homotrimer. J. Mol. Biol. 305 , 291–305 (2001). doi: 10.1006/jmbi.2000.4310.

The image of the meat structure used is from: OpenStax, CC BY 4.0. https://creativecommons.org/licenses/by/4.0 , via Wikimedia Commons.

Plant-based carbohydrates

Carbohydrates, such as sugars, oligosaccharides, or polysaccharides, can also be used as functional ingredients to assemble animal product analogs 11 . Plant-derived carbohydrates exhibit different molecular, physicochemical, functional, and biological properties depending on their biological origin and isolation procedures. These ingredients may be used to provide a variety of functional attributes in plant-based foods, including sweetness, thickness, gelling, emulsification, structure formation, stabilization, and fluid holding 12 . They may also be digestible or indigestible (i.e., fibers), as well as fermentable or non-fermentable, which impacts human nutrition and health. It is therefore important to select carbohydrate ingredients that provide the required quality and nutritional attributes in the end product. Polysaccharides are often used in combination with proteins to obtain desirable textural and sensory properties in plant-based foods via phase separation and interactive mechanisms 13 .

Plant-based lipids

Plant-based fats and oils can be economically extracted from various lipid-rich botanical sources, including algae, canola, coconut, cocoa, corn, flaxseed, olive, palm, safflower, soybean, and sunflower. For many applications, the ability of the triacylglycerols to form a 3D network of fat crystals is important, as it provides desirable textural attributes, such as the plasticity of butter and spreads (Fig. 3 ). Moreover, the change in the solid fat content with temperature plays a critical role in the functionality of many foods. This is particularly important when trying to mimic the behavior of animal fats with plant fats. The melting point of fats increases as the number of carbon atoms in the fatty acid chains increases or the number of double bonds decreases. The crystallization characteristics of fats are responsible for many of the desired quality attributes of animal products, such as butter spreadability, whipped cream foamability, cheese meltability, and ice cream hardness. For this reason, it is often important to simulate the crystallization characteristics of animal fats using plant-derived ones. This is often challenging because plant-derived fats contain more unsaturated fatty acids than animal fats and so tend to be more fluid-like at ambient temperatures. This problem can be overcome by increasing the degree of saturation of these fats using hydrogenation, but this may have adverse nutritional effects. As a result, food manufacturers often use naturally occurring high-melting plant-derived fats in their products, such as cocoa butter and coconut oil, but these also have high degrees of saturation that may have adverse health effects, such as an increased risk of heart disease 7 .

The SFC-temperature profile of an edible fat determines its functionality.

The type of fatty acids present in plant-derived fats and oils also influences their nutritional profile and oxidative stability. Fats and oils containing high levels of polyunsaturated fatty acids (PUFAs), particularly omega-3 ones (like flaxseed or algae oils), have been claimed to have beneficial health effects, such as the ability to reduce heart and brain diseases 14 , 15 . Although further studies are required to substantiate these claims using randomized clinical trials and meta-analysis. These fats may be used as an alternative to fish oils, which are rich in omega-3 PUFAs. Even so, it is important to prevent these PUFAs from oxidizing during storage and processing since this leads to the generation of undesirable off-flavors and toxic reaction products 16 , 17 . This may be achieved using numerous strategies including controlling temperature, oxygen, and light levels; reducing pro-oxidant contamination; incorporating antioxidants; utilizing chelating agents, or structuring approaches 18 , 19 , 20 . Utilization of these approaches will be important for creating the next generation of nutritionally-fortified plant-based foods.

Other additives

The creation of high-quality plant-based foods also requires the utilization of various other additives, including colors, flavors, buffers, preservatives, and crosslinking agents 21 . Ideally, these ingredients should be natural botanical ingredients, like natural pigments (e.g., carotenoids, anthocyanins, and curcuminoids) or preservatives (e.g., essential oils or antimicrobial peptides).

The science behind plant-based foods

In general, plant-derived ingredients are being used to create a wide range of food products to replace animal-based ones (such as meat, fish, eggs, and milk) or that normally require animal ingredients as key components (such as cheese, dressings, sauces, spreads, and yogurts) (Table 1 ). Here, we give a brief overview of the science and technology behind the formulation of the main categories of plant-based alternatives: meat, milk, and egg.

Plant-based meat analogs

The recent commercial success of plant-based meat products, such as those produced by Beyond Meat and Impossible Foods, has had a profound impact on the modern food industry 21 . Indeed, the market for plant-based meats in the US was nearly $940 million in 2019, with a 38% increase from two years before (Table 1 ).

The food industry has been highly successful in producing high-quality analogs of comminuted meat products, such as burgers, sausages, nuggets, and ground meat since texturized vegetable proteins (TVPs) can be used to simulate their structures. However, it has proved much more challenging to create products that accurately mimic the properties of whole muscle tissue, which consists of muscle fibers, connective tissue, and adipose tissue organized into complex hierarchical structures (Fig. 2 ). The structural arrangement of these tissues plays a critical role in determining the physicochemical and sensory attributes of real meat products 22 .

The production of high-quality plant-based whole muscle analogs requires selecting the most appropriate ingredients and processing operations to simulate muscle fiber, connective, and adipose tissue (Fig. 4 ). Here, we highlight some of the key factors that should be considered when designing meat analogs that faithfully simulate the attributes of real meat. More details about this topic can be found in a number of recent review articles 23 , 24 , 25 . Ideally, meat analogs should reliably mimic the desirable characteristics of real meat products before, after, and during cooking. Meat analogs are mainly constructed from plant-derived macronutrients (fats, proteins, and polysaccharides), but also contain micronutrients and other additives, such as vitamins, minerals, colors, flavorings, binders, and preservatives 21 . The ingredients and processing operations used to produce these analogs must be optimized for each specific meat product being mimicked.

The authors thank Xiaoyan Hu and Cheryl Chung (UMASS) for providing the images of adipose tissue and plant-based muscle fibers. The image of the muscle fibers is by Nephron and is licensed under CC BY-SA 3.0. The image of the raw beef steak is by Jellaluna and is licensed under CC BY 2.0.

The opaque nature of real meat can be simulated by including particles or fibers with dimensions (200–2000 nm) that scatter light strongly. The surface sheen of meat can be simulated by controlling the surface roughness and wetness of meat analogs. The analogs should have a wet smooth surface before heating leading to specular reflectance and a shiny look, but a rough dry surface after heating leading to diffuse reflectance and a matt look. The color of real meat is simulated by incorporating natural pigments that selectively absorb light at appropriate wavelengths. For instance, a beef analog should be pinky-red before cooking and brown after cooking. For some products, such as microwavable ones, it is only required to reproduce the brownish color of the cooked product.

Food companies have used various strategies to simulate the color of real meat in their plant-based alternatives. Beyond Meat TM uses an extract from beet juice extract containing betalain (a natural pigment) to recreate the desirable color of meat. The betalain undergoes a chemical transformation when heated, causing it to turn from reddish-violet to orangey-yellow 26 , 27 . Impossible Foods TM uses a plant-based heme protein, leghemoglobin, in their products. In principle, leghemoglobin can be extracted from the roots of soybeans, but in practice, it is more economically viable to generate it by microbial fermentation. Other natural pigments can be used either alone or in combination to create desirable meat-like color characteristics 28 .

It is possible to simulate the textural attributes of comminuted meat products (sausages, burgers, and nuggets) fairly accurately using TVPs, which has led to highly successful commercial plant-based products such as those from Impossible Foods TM and Beyond Meat TM  25 . It is much more challenging to simulate the delicate texture and mouthfeel of whole muscle products, like beef steaks, chicken breast, or pork chops because of their complex hierarchical structures (Fig. 2 ). A range of scientific and technological approaches are being explored for their potential in creating structures from plant-derived ingredients that simulate those found in real meat, with the ultimate aim of accurately mimicking their texture and mouthfeel 29 . These approaches can be grouped into two different categories that may be used separately or combined: physicochemical and processing approaches.

Physicochemical approaches are based on controlling the molecular interactions and organization of plant-derived biopolymers to create meat-like structures 24 , 30 . Typically, a mixture of plant proteins and polysaccharides is used for this purpose. Appropriate mixtures of biopolymers can be made to phase separate by controlling the ingredient types and concentrations, as well as solution properties such as pH, mineral composition, and temperature (Fig. 4 ). The two main phase separation approaches involved are thermodynamic incompatibility and coacervation, which are based on inducing either repulsive or attractive interactions between the two types of biopolymers, respectively. This leads to the formation of a water-in-water (W/W) emulsion that contains two aqueous phases with different compositions. A mild shear force is then applied to the phase-separated biopolymer solution, resulting in the generation of fiber-like structures. These structures can then be locked into place by adding a suitable gelling agent or by changing the temperature (cooling or heating). This approach can be used to form fibrous structures that simulate some of the characteristics of those found in real meat, thereby leading to some similar physicochemical attributes (Fig. 5 ).

Image of soybeans from CSIRO (CC BY 3.0). Image of “Soy Milk” by Kjokkenutstyr.net is licensed under CC BY-SA 2.0 ( www.kjokkenutstyr.net ).

Plant-derived biopolymers can also be used to form meat-like structures using certain kinds of mechanical processing devices, such as extruders or high shear cells. As an example, protein-water mixtures are fed into an extrusion device, which mixes and shears them under high pressure and then extrudes them through a shaped die to form meat-like structures and textures 29 , 31 , 32 . Alternatively, these structures and textures can be formed by placing a mixture of proteins and polysaccharides into a specially designed cone-in-cone shear cell, which applies strong shear forces to the mixture by rotating one or both of the plates at a high speed. The biopolymer mixture can also be heated within the cell during the shearing process to promote protein unfolding and aggregation. As a result, the proteins organize into fiber-like structures that somewhat resemble the structure of meat fibers 13 . Extrusion methods are currently the most common processing method to create meat-like textures in commercial products, but the shear cell is also finding increasing use.

Cooking loss

An important attribute of real meat products is their ability to retain/lose fluids during cooking, as their fluid content impacts their look, feel, mouthfeel, and cooking properties. It is therefore important that meat analogs simulate the fluid-holding properties of real meat. Researchers have used fundamental physical chemistry models to identify the key factors impacting the fluid-holding properties of meat analogs: the interactions between the solvent and biopolymer molecules; the elastic modulus of the gel network formed by the biopolymer molecules; and, the osmotic pressure generated due to a concentration imbalance of mineral ions inside and outside the gel network 33 . The fluid holding properties of meat analogs can therefore be manipulated by altering biopolymer type, concentration, and crosslinking. In addition, the incorporation of polysaccharides can be used to improve the fluid holding properties 34 .

Hundreds of aromatic molecules have been reported in meat products, but only some of these play a critical role in determining their characteristic flavor profiles 35 . The aroma profile depends on the type of meat and cooking method used. In cooked meat, the aromatic molecules are mainly the result of complex chemical reactions involving protein, carbohydrate, and lipid molecules, particularly Maillard and oxidation reactions. The taste of cooked meat depends on the balance of non-volatile molecules present that interact with umami, salt, sweet, bitter, and sour receptors in the mouth. These molecules may be present within the original raw animal flesh or they may be produced as a result of the cooking processes used.

Information about the most important flavor constituents within real meat products can be used to identify plant-based alternatives that provide meaty flavors in meat analogs. Impossible Foods uses soy leghemoglobin produced by fermentation processes to create “meaty” notes in their commercial meat analogs. The heme iron in leghemoglobin is exposed during cooking, thereby promoting oxidative reactions that generate aromatic compounds similar to those produced in real meat 36 . Mycoproteins, which are also produced using fermentation processes, are being utilized for their ability to produce meat-like aromas, tastes, and textures 37 . Algae and microalgae are being used in plant-based fish and other marine products because they provide seafood-like flavors 37 . Plant-derived materials can be used as precursors to form meaty flavors by carrying out controlled Maillard and oxidation reactions 38 . Research is also being carried out to reduce the undesirable flavors found in some plant-derived ingredients, e.g., the beany, earthy, astringent, or vegetative notes associated with chickpea, mung bean, or pea proteins 38 .

Nutritional profile

A major challenge when developing plant-based meat analogs is to match the nutritional profile of the original product. Meats contain high levels of protein, as well as essential micronutrients, such as zinc, iron, and vitamin B. Moreover, these micronutrients are often present in a highly bioavailable form within animal products. Consequently, it is important to design plant-based meat analogs that are enriched with bioavailable forms of these micronutrients. This can often be achieved using advanced encapsulation technologies, such as emulsions or nanoemulsions 39 .

Plant-based milk analogs

Plant-based milk analogs are currently the most commonly consumed plant-based food products, contributing over 40% of the market sales in this sector (Table 1 ) 8 . The raw materials, processing methods, physicochemical properties, sensory attributes, and nutritional profiles of milk analogs products have been reviewed in a number of recent articles 8 , 40 , 41 , 42 , 43 . For this reason, only a short overview of these products is given here, with an emphasis on their fundamental properties.

Raw materials and production

Milk analogs are complex colloidal dispersions comprised of various kinds of particles, including oil bodies, fat droplets, protein aggregates, plant tissue fragments, and/or insoluble calcium carbonate particles, dispersed in an aqueous medium containing soluble proteins, polysaccharides, sugars, and salts 41 . Creating high-quality milk analogs, therefore, requires basic knowledge of colloid and interface science, such as particle reduction technologies, light scattering theory, and particle instability mechanisms. Milk analogs are typically created using two approaches: (i) plant tissue disruption; (ii) homogenization (Fig. 5 ) 41 . The first approach involves unit operations such as soaking, mechanical disruption, enzymatic hydrolysis, separation, formulation, homogenization, and thermal treatment to break down plant materials (such as soybeans, flaxseeds, almonds, or coconut flesh) into small particles. The second approach involves blending isolated plant-based ingredients (e.g., oils, emulsifiers, and thickeners) with water followed by homogenization and thermal treatment to produce an emulsion containing small droplets 41 . These processes must be carefully controlled to create stable milk analogs with the appropriate physicochemical, sensory, and functional attributes. Gravitational separation and aggregation can be inhibited by ensuring all the particles are sufficiently small (<500 nm), which can be achieved using appropriate chemical, enzymatic or mechanical size-reduction methods. Plant-based stabilizers, such as emulsifiers or thickening agents, may also be included to improve emulsion formation and stability. Plant-based emulsifiers include surface-active proteins (e.g., soy, pea, fava bean, and lentil proteins), polysaccharides (e.g., modified starches), phospholipids (e.g., soy and sunflower lecithin), or surfactants (e.g., quillaja and tea saponins) 44 . Plant-based thickening agents may be added to modify the textural characteristics or inhibit particle separation, which is usually polysaccharides like pectin, locust bean gum, gellan gum, starch, methylcellulose, carrageenan, and alginate 45 . The ingredients and processing operations used are optimized to create milk analogs that mimic the desirable properties and functional performance of cow’s milk 41 . Milk analogs may also be fortified with micronutrients to provide nutrients that may be deficient in plant-based diets, such as vitamin D, vitamin B 12 , and calcium 40 .

Appearance and sensory

A creamy appearance can be achieved in milk analogs by controlling the concentration and size of the colloidal particles they contain, such as oil bodies, fat droplets, and tissue fragments. Their lightness increases with increasing particle concentration and when the particles have similar dimensions to light waves (380–780 nm). The inherent color of milk analogs depends on the type and concentration of natural pigments they contain 46 . To achieve a desirable appearance it is often necessary to add or remove certain natural pigments.

The sensory attributes of cow’s milk are difficult to recreate because it has a bland but characteristic flavor profile, with over 100 volatile compounds typically present 47 , 48 . In contrast, milk analogs contain flavors arising from the plant’s raw materials, as well as generated during processing and storage. For instance, soymilks often have a beany flavor, whereas hazelnut milk has a nutty flavor 43 . Moreover, phytochemicals such as phenols and glucosinolates may introduce off-flavors, such as bitter, earthy, or vegetative notes 38 . Researchers are therefore developing new plant breeds and new processing methods to reduce off-flavors in milk analogs, including blanching and fermentation 49 .

The nutritional profile of plant-based milk products is often inferior to that of real milk 40 . Cow’s milk naturally contains high levels of vitamin A and calcium, which may be lacking in a plant-based diet. This problem can be overcome by using advanced encapsulation technologies to fortify plant-based milk with bioavailable forms of these micronutrients 40 .

Plant-based egg analogs

Whole hen’s eggs are mainly comprised of water (75%), proteins (12%), and lipids (12%), and contain a diverse range of constituents that contribute to their various functional applications in foods, such as emulsification, foaming, water holding, and gelation 50 . As a result, they are versatile ingredients that can be used in many different foods, including alone (boiled, scrambled, poached, or fried eggs) or as a critical part of other foods (like mayonnaise, dressings, baked goods, and desserts). Ideally, plant-based egg analogs should simulate these desirable physiochemical and functional attributes. One of the most important functional attributes is the ability to undergo a sol–gel transition when heated under similar cooking conditions as used for real eggs. Ideally, the globular plant proteins used in egg analogs should therefore have a denaturation temperature in the same range as real egg proteins (i.e., around 63–93 °C), but many plant proteins only denature at higher temperatures (e.g., around 90 °C for soy glycinin 51 ). As a result, higher temperatures or longer heating times are often required to achieve the same structure formation and textural attributes as real eggs. Instrumental methods like differential scanning calorimetry and dynamic shear rheometry can be used to provide information about protein denaturation and gelation temperatures. Typically, it is important that the plant proteins used are in a native state prior to heating, which means their isolation conditions must be carefully controlled. The nature of the gels formed depends on protein type (e.g., soybean, pea, chickpea, bean, and sunflower), protein concentration, and environmental conditions (e.g., ionic strength, pH, and thermal history), which should therefore all be carefully controlled 52 . In some applications, the plant-based ingredients in egg analogs should also exhibit good emulsifying properties, such as in mayonnaise or dressings. Plant proteins or phospholipids used for this purpose should typically be soluble in water, capable of adsorbing to oil droplet surfaces, and able to stabilize oil droplets from aggregation. In some cases, other plant-based ingredients may also be required to prevent destabilization of the product, such as thickening agents that inhibit gravitational separation. The yellowish appearance of egg yolks may be achieved by adding natural pigments (such as curcumin or carotenoids), while an appropriate flavor profile may be achieved by adding natural flavors, herbs, or spices.

Many different egg analogs have been developed over the years, with JUST Egg TM ( www.ju.st ) being one of the most successful recently. Two products are currently on the market from this company: (i) fluid eggs intended to prepare scrambled eggs or omelets; (ii) frozen egg slices that can be heated and used in breakfast sandwiches. Mung bean protein and emulsified canola oil are two of the main components of these products. The proteins unfold and aggregate during cooking leading to a gel-like texture. The canola oil droplets contribute to the opaque appearance, textural attributes, flavor profile, and mouthfeel of the final product. These products also contain transglutaminase, an enzyme that crosslinks the proteins, thereby increasing the gel strength and water holding capacity so as to better mimic real egg 53 . The yellowish color of eggs is mimicked in these products by adding turmeric, which contains curcumin. Other functional ingredients are also added to more closely simulate the properties of real eggs, including thickeners/stabilizers (e.g., corn starch and gellan gum), seasonings (e.g., garlic powder, onion powder, sugar, and salt), buffering salts (e.g., bicarbonates, citrates, or phosphates), and preservatives (e.g., nisin). In the future, more research is still required to improve the functional versatility of egg analogs and to enhance their nutritional profiles.

The nutritional profile of plant-based eggs is often worse than that of real hen’s eggs. Hen’s eggs naturally contain a variety of vitamins and minerals that are not commonly found in a plant-based diet. For this reason, it is often important to fortify plant-based egg products with bioavailable forms of these micronutrients, which often require the utilization of advanced encapsulation technologies.

Conclusions and future directions

Recent reports suggest that human and global health would be greatly improved by replacing animal-based foods (such as meat, fish, eggs, milk, and their products) with plant-based alternatives. This transition would be facilitated by the availability of more plant-based foods that are affordable, convenient, sustainable, nutritious, and tasty. Consumers would then find it easier to change their dietary habits and adopt a more healthy and sustainable diet. There are, however, various hurdles that need to be addressed to achieve this goal:

Consumer-based hurdles : Improved knowledge of the behavior of consumers is needed to create effective approaches to encourage them to try, like, and adopt plant-based foods. There has already been a considerable amount of consumer research carried out for certain kinds of plant-based products 54 , 55 , 56 . However, more research is required to develop effective materials to educate consumers about the potential benefits and drawbacks of consuming plant-based foods so they can make informed choices.

Technological-based hurdles : The creation of plant-based foods is being held back by a lack of high-quality plant-derived ingredients, particularly proteins, as well as large-scale manufacturing processes to convert these ingredients into desirable end products. In particular, it is still challenging to create analogs of whole muscle meat, fish, yogurt, and cheese because of their complex structural hierarchies. Consequently, more research is required to understand the relationship between the structure and properties of plant-based ingredients and their ability to form high-quality meat, fish, egg, or dairy analogs people want to consume.

Commercial-based hurdles : The commercialization of plant-based foods is being held back by a lack of knowledge about the relative advantages and disadvantages of different plant-derived ingredients and manufacturing processes, as well as of safety concerns (such as allergenicity), regulations in different countries, and supply chain issues. Increased knowledge about these issues would help companies to successfully enter the plant-based food market.

Social-based and economic-based hurdles : Changes in government policies, such as taxation, incentives, and educational programs, would facilitate the transition to a more plant-based diet. However, improved knowledge about the social, economic, environmental, and health implications of replacing animal products with plant-based ones is still required to craft and implement these policies.

In the future, it will be important for governments, industries, and non-profit organizations to support efforts to obtain this information, thereby facilitating a more rapid transition to a healthy and sustainable plant-based diet. It should also be noted that many plant-based foods are highly processed and contain numerous additives, which is undesirable to many consumers. Consequently, there is a need for more research on the development of processed plant-based foods that contain fewer ingredients and involve less processing. In addition, it is often assumed that plant-based foods are healthier than animal-based ones. But this is often not the case. More research is required to ensure that plant-based foods are carefully designed to ensure that they have beneficial nutrient profiles and that the nutrients are in a bioavailable form.

Data availability

Data sharing not applicable. This is a review article and no new datasets were generated or analyzed during this study.

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This work was supported by the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, grant number: 2020-03921. It was also supported by funding provided by the Good Food Institute.

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• Diet & Nutrition

Is Eating a Plant-Based Diet Better for You?

I t’s no secret that fruits and veggies are good for you. But a new Netflix show , You Are What You Eat: A Twin Experiment , shows just how powerful—and fast-acting—they can be.

The show features pairs of adult identical twins who participated in a study published in November 2023 . For eight weeks, everyone in the study ate a diet rich in fruits, vegetables, whole grains, and legumes and low in sugars and refined starches. But one twin from each pair was assigned to eat only these plant-based foods, while the other also ate animal products such as chicken, fish, eggs, and dairy.

Both groups saw improvements in their cholesterol levels and modest reductions in weight over the eight weeks, but those trends were more dramatic among twins who followed the vegan diet. Average fasting insulin levels—another marker of cardiometabolic health—also dropped among the vegan, but not omnivorous, twins.

“This suggests that anyone who chooses a vegan diet can improve their long-term health in two months,” Christopher Gardner, a Stanford University professor and senior author of the study, said in a statement . And, Gardner added, following a vegan diet may not be as difficult as many people imagine: 21 of the 22 twins assigned to that eating plan stuck with it for all eight weeks.

Another point for plants

The Stanford study is not the only recent evidence pointing to the promise of plant-rich diets. A study published December 2023 in JAMA Network Open found that people who eat low-carbohydrate diets rich in plant-based proteins and fats, as well as whole grains, tend to gain less weight over time than people who eat low-carb diets with a lot of animal products and refined starches.

More From TIME

“Having a diet that’s rich in fresh fruits, non-starchy vegetables, whole grains, nuts, legumes, and plant-based oils is advisable for maintaining or improving your overall health,” says Binkai Liu, a research assistant in the Harvard T.H. Chan School of Public Health’s nutrition department and first author of the JAMA Network Open study.

Two recent analyses of previously published studies also found benefits associated with plant-based diets. The first linked vegetarian diets to a lower risk of heart disease than omnivorous diets, while the second , like the twin study, found that vegan and vegetarian diets are associated with lower levels of cholesterol and other markers of potential heart problems.

Which is more important: more plants or less meat?

In addition to validating plant-based diets, studies have long shown that eating too much meat—particularly red and processed meat, such as sausage and bacon—is linked to health problems including heart disease and cancer . But is all meat consumption bad?

It's debatable. Some studies and experts refute the idea that vegan diets are automatically healthier than those that include meat. Becoming a vegan or vegetarian can make it difficult to get certain nutrients found in animal products, such as vitamins B12 and D, and people who eliminate meat often replace it with foods that may limit the nutritional benefits of a vegetarian lifestyle . Plus, numerous studies suggest that people who eat a Mediterranean diet —which includes fish— tend to live longer and report better health than people who follow other eating styles.

In the statement, Gardner said that cutting out all meat shouldn’t necessarily be everyone’s goal. “What’s more important than going strictly vegan,” Gardner said, “is including more plant-based foods into your diet.” Even the omnivores in his study, after all, saw some drops in cholesterol and body weight after eight weeks, likely in part because they ate plenty of fresh foods high in fiber and low in saturated fat.

A study from 2017 backs up that idea. Researchers tracked a group of people for more than a decade to see how dietary changes affected longevity. They estimated that even one small daily change—swapping a serving of red or processed meat for nuts or legumes—translated to an 8% to 17% drop in early death risk.

It’s hard to make one-size-fits-all statements when it comes to nutrition, as people’s bodies are unique and have different needs. Another twin study , this one from 2019, found that even people share nearly all of their DNA can have different physiological responses to the same foods, for example.

But if there’s any universal truth in nutrition science, it seems to be that loading up your plate with plants is always a good decision.

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Food intakes, anthropometry and physiology, major diseases: cvd and diabetes, other disorders, all-cause mortality, strengths, weaknesses and interpretation of the findings, conclusions, financial support, conflict of interest, plant-based diets and long-term health: findings from the epic-oxford study.

Published online by Cambridge University Press:  27 October 2021

The concept of plant-based diets has become popular due to the purported benefits for both human health and environmental impact. Although ‘plant-based’ is sometimes used to indicate omnivorous diets with a relatively small component of animal foods, here we take it to mean either vegetarian (plant-based plus dairy products and/or eggs) or vegan (100% plant-based). Important characteristics of plant-based diets which would be expected to be beneficial for long-term health are low intakes of saturated fat and high intakes of dietary fibre, whereas potentially deleterious characteristics are the risk of low intakes of some micronutrients such as vitamin B 12 , vitamin D, calcium and iodine, particularly in vegans. Vegetarians and vegans typically have lower BMI, serum LDL cholesterol and blood pressure than comparable regular meat-eaters, as well as lower bone mineral density. Vegetarians in the EPIC-Oxford study have a relatively low risk of IHD, diabetes, diverticular disease, kidney stones, cataracts and possibly some cancers, but a relatively high risk of stroke (principally haemorrhagic stroke) and bone fractures, in comparison with meat-eaters. Vegans in EPIC-Oxford have a lower risk of diabetes, diverticular disease and cataracts and a higher risk of fractures, but there are insufficient data for other conditions to draw conclusions. Overall, the health of people following plant-based diets appears to be generally good, with advantages but also some risks, and the extent to which the risks may be mitigated by optimal food choices, fortification and supplementation is not yet known.

The term ‘plant-based diets’ has been used for more than 20 years, with discussion of potential benefits and risks ( Reference Mann 1 ) . There is no universally agreed definition of the term, and although some have used it to refer to omnivorous diets with a low content of animal source foods (e.g. meat and fish), the threshold for this has not been agreed and here we take the pragmatic approach of using it to refer to vegetarian (lacto-ovo-vegetarian: plant-based except for dairy products and or eggs) and vegan diets (100 % plant-based).

Evidence on the health-status of vegetarians and vegans comes from a substantial number of relatively small cross-sectional studies which compare their dietary intakes, nutritional status and physiological characteristics with those of meat-eaters, together with a small number of prospective cohort studies which follow the health of these groups over many years. This review is based largely on results from EPIC-Oxford (the European Prospective Investigation into Cancer and Nutrition Oxford cohort), with some results from the earlier Oxford Vegetarian Study and from the UK Biobank ( Reference Davey, Spencer and Appleby 2 – Reference Allen, Sudlow and Peakman 4 ) . EPIC-Oxford is a cohort of 65 000 men and women living throughout the UK and was established in the 1990s with recruitment targeted to identify as many vegetarians as possible, and 50 % of the participants do not eat meat; some analyses of EPIC-Oxford, on cancer and mortality, also include data from the Oxford Vegetarian Study which used similar methods of recruitment and follow-up of 11 000 people recruited in the early 1980s. UK Biobank is a cohort of 500 000 men and women in the UK established between 2006 and 2010; recruitment was not targeted at vegetarians, but due to the large size of the cohort it includes several thousand vegetarians and several hundred vegans. In this review, we describe the relationships of plant-based diets with nutritional intakes, physiological and biochemical characteristics, and long-term health.

Vegetarian and vegan diets are defined by the foods that are excluded, but examination of the composition of such diets shows typical patterns by which they differ from omnivorous diets. In EPIC-Oxford, vegetarians and vegans have much higher intakes compared to regular meat-eaters of soya, legumes, nuts and other moderately high-protein plant foods, substantially higher intakes of relatively unprocessed cereals, and modestly higher intakes of fruit and vegetables ( Reference Papier, Tong and Appleby 5 ) ; this pattern is consistent with the expectation that the energy and other nutrients supplied in omnivorous diets by meat, fish and dairy products will be largely replaced by the types of plant foods which contain substantial amounts of energy and protein, rather than by plant foods such as fruit and vegetables which are generally low in energy and protein. A similar pattern was seen in UK Biobank ( Reference Bradbury, Tong and Key 6 ) .

As a consequence of the foods consumed, vegetarian and vegan diets typically have a different pattern of nutrient intake from omnivorous diets, with relatively high intakes of carbohydrates, n -6 fatty acids, dietary fibre, carotenoids, folate, vitamin C, vitamin E and magnesium, and relatively low intakes of protein, saturated fat, long-chain n -3 fatty acids, retinol, vitamin B 12 and zinc; vegans may have particularly low intakes of vitamin B 12 , calcium and iodine, and plant-based diets are generally devoid of haem iron. For most of these nutrients, the relevance of these differences in terms of long-term health is not yet clear; here, we focus mainly on intakes of protein, saturated fat, dietary fibre, vitamin B 12 and calcium.

Dietary intakes in EPIC-Oxford have been assessed at baseline and, in approximately half the cohort, at re-survey about 14 years later ( Reference Davey, Spencer and Appleby 2 , Reference Sobiecki, Appleby and Bradbury 7 ) . At re-survey, mean protein intakes as percent energy were 17⋅2, 15⋅5, 14⋅0 and 13⋅1 % in meat-eaters, fish-eaters, vegetarians and vegans, respectively; the proportions of participants estimated to have inadequate protein intakes were less than 5 % in meat-eaters and fish-eaters, but were 9⋅8 and 6⋅0 % respectively in male and female vegetarians, and 16⋅5 and 8⋅1 % respectively in male and female vegans. These findings should be interpreted cautiously, for example because the dietary questionnaires may not have included some protein-rich foods consumed by vegetarians and vegans (e.g. vegan cheese), but they raise the possibility that protein intake might be inadequate in some of the vegetarians and vegans in this population. Plasma concentrations of amino acids have been measured in a subsample of male participants: circulating non-fasting concentrations of the essential amino acids lysine, methionine, leucine, valine and tryptophan were 6–13 % lower in vegans (but not in vegetarians) compared to those in meat-eaters ( Reference Schmidt, Rinaldi and Scalbert 8 ) .

Saturated fat intake is typically lower in vegetarians, and especially in vegans, compared to that in meat-eaters. This is to be expected because meat is a major source of saturated fat; for example, in the UK's National Diet and Nutrition Survey for years 2014–2016, meat and meat products provided 24 % of saturated fat intake in men and women aged 19–64 ( 9 ) . In EPIC-Oxford, saturated fat intakes at follow-up as percent energy were 10⋅4, 9⋅4, 9⋅5 and 6⋅9 % in meat-eaters, fish-eaters, vegetarians and vegans, respectively ( Reference Sobiecki, Appleby and Bradbury 7 ) . It is likely that the reason that saturated fat intake in vegetarians in EPIC-Oxford is only modestly lower (about 9 %) compared to that in meat-eaters is because the vegetarians eat about 50 % more cheese compared to meat-eaters, partly as a substitute for meat ( Reference Papier, Tong and Appleby 5 ) .

Unrefined plant foods are rich in dietary fibre ( 10 ) . In EPIC-Oxford, fibre intakes at follow-up were 21⋅7, 24⋅9, 25⋅6 and 28⋅9 g/d of non-starch polysaccharides in meat-eaters, fish-eaters, vegetarian and vegans, respectively ( Reference Sobiecki, Appleby and Bradbury 7 ) ; these intakes would probably be about 30 % higher if expressed as g/d of AOAC (Association of Analytical Chemists) fibre ( 10 ) .

Plants cannot synthesise vitamin B 12 and generally contain none (there may be some exceptions such as duckweed due to the presence of bacteria inside the plant tissue ( Reference Kaplan, Zelicha and Tsaban 11 ) ); therefore, vegans would be expected to have zero intake unless they consume foods fortified with vitamin B 12 and/or vitamin B 12 supplements. Vegetarians obtain vitamin B 12 from dairy products and/or eggs, but on average their intakes are lower than those of meat-eaters. It is difficult to obtain accurate estimates of intakes of vitamin B 12 in vegetarians and vegans because of the need for detailed information on the use of fortified foods and supplements, but blood measurements can provide information on status. In a sub-sample of male participants in EPIC-Oxford, mean serum vitamin B 12 concentrations were 281, 182 and 122 pmol/l in meat-eaters, vegetarians and vegans, respectively, and 52 % of vegans, 7 % of vegetarians and <1 % of meat-eaters had concentrations below 118 pmol/l indicating deficiency ( Reference Gilsing, Crowe and Lloyd-Wright 12 ) .

Calcium intakes typically differ little between meat-eaters, fish-eaters and vegetarians, but are substantially lower in vegans; in the UK, milk and milk products supply 34 % of dietary calcium in men and women aged 19–64 ( 9 ) . In EPIC-Oxford, average intakes at follow-up in the four dietary groups were 1083, 1131, 1117 and 848 mg/d, respectively; intakes in vegans at recruitment were substantially lower, 582 and 610 mg/d in women and men, respectively, and the higher intakes in vegans at follow-up may be explained by more questions on the questionnaire, and greater availability in shops, for plant-based dairy replacements with calcium fortification.

For several other micronutrients, nutritional status is best assessed by measuring concentrations in the blood. Such analyses have shown that vegetarians and particularly vegans in EPIC-Oxford have lower plasma concentrations compared to meat-eaters of EPA, DHA and vitamin D ( Reference Rosell, Lloyd-Wright and Appleby 13 , Reference Crowe, Steur and Allen 14 ) . Haematological measures have not been made in EPIC-Oxford, but analyses of data for white British premenopausal women in UK Biobank have shown that Hb concentrations were lower in vegetarians compared to that in regular meat-eaters, with 12⋅7 % of vegetarians compared to 8⋅7 % of regular meat-eaters categorised as anaemic; data were available for only seventy-six vegans, among whom six (7⋅9 %) were anaemic ( Reference Tong, Key and Gaitskell 15 ) .

At recruitment, the mean BMIs of both male and female vegetarians and vegans in EPIC-Oxford were approximately 1 and 2 kg/m 2 lower than those of meat-eaters, respectively ( Reference Davey, Spencer and Appleby 2 ) . During the first 5 years of follow–up, meat-eaters gained approximately 400 g per year; weight gain was similar in vegetarians, whereas weight gain in vegans was significantly less at approximately 300 g per year ( Reference Rosell, Appleby and Spencer 16 ) . The lower BMI of vegetarians, and especially vegans, compared to that of meat-eaters in this population would be expected to lead to a lower risk of several diseases linked to obesity, but also a higher risk of any disorders linked to underweight.

Plasma concentrations of non-HDL cholesterol by diet group were measured in a large sample of men and women in EPIC-Oxford ( Reference Bradbury, Crowe and Appleby 17 ) ; non-HDL-cholesterol was measured as a surrogate for LDL-cholesterol and in the remainder of the present paper, for convenience, we refer to the differences noted in non-HDL-cholesterol as differences in LDL-cholesterol. In men, mean LDL-cholesterol was 0⋅85 mmol/l lower in vegans compared to meat-eaters, the difference reduced to 0⋅68 mmol/l lower after adjusting for BMI; the differences in women were 0⋅49 and 0⋅40 mmol/l, respectively, and mean concentrations in vegetarians were intermediate. Blood pressure was also found to be lower in vegans than that in meat-eaters, partly due to lower BMI; differences in mean systolic blood pressure between vegans and meat-eaters before and after adjusting for BMI were 4⋅2 and 2⋅6 mmHg, respectively, in men and 2⋅4 and 1⋅8 mmHg, respectively, in women, whereas the differences in blood pressure between vegetarians and meat-eaters were very small ( Reference Appleby, Davey and Key 18 ) .

Bone density has not been assessed in EPIC-Oxford, but heel bone mineral density has been measured in almost all participants in UK Biobank. In white British women, the heel bone density test t -scores were −0⋅54, −0⋅62 and −0⋅80 in regular meat-eaters, vegetarians and vegans, respectively; these measures were −0⋅55, −0⋅61 and −0⋅77, respectively, after adjusting for body weight ( Reference Tong, Key and Sobiecki 19 ) . The lower bone density test t -scores in vegans after allowance for body weight may be related to their lower intakes of micronutrients such as calcium and vitamin D, but other factors might be involved perhaps including the differences in protein intake.

Fig. 1 summarises findings on the associations of vegetarian diets with long-term health in EPIC-Oxford; the results plotted are those for which there was evidence for a difference in risk between meat-eaters and vegetarians (either in the BMI-adjusted or -unadjusted model for outcomes where we showed both models). Fig. 2 shows the equivalent results for which there was evidence for a difference in risk between meat-eaters and vegans. Slight differences in the categorisation of the comparison group in some analyses are given in footnotes to Figs. 1 and 2 .

Fig. 1. Risk of various conditions in vegetarians compared with meat-eaters in the EPIC-Oxford study. *Includes data from EPIC-Oxford and the Oxford Vegetarian Study combined. † Adjusted for BMI. ‡ Vegetarians and vegans combined. The hazard ratios and 95 % CIs presented are in reference to the following groups: regular meat-eaters who consume 50+ g of meat daily (diabetes); high meat-eaters who consumed 100+ g of meat daily (kidney stones and cataracts); meat-eaters (IHD, total and haemorrhagic stroke, all cancers and subtypes, all fractures and hip fractures, diverticular disease); non-vegetarians who eat meat or fish (gallstones).

Fig. 2. Risk of various conditions in vegans compared with meat-eaters in the EPIC-Oxford study. *Includes data from EPIC-Oxford and the Oxford Vegetarian Study combined. † Adjusted for BMI. The hazard ratios and 95 % CIs presented are in reference to the following groups: regular meat-eaters who consume 50+ g of meat daily (diabetes); high meat-eaters who consumed 100+ g of meat daily (cataracts); meat-eaters (all cancers, all fractures and hip fractures, diverticular disease).

Compared to meat-eaters, the vegetarians in EPIC-Oxford had a 23 % lower risk of IHD after 18 years of follow-up ( Reference Tong, Appleby and Bradbury 20 ) . For vegans, the risk estimate was 18 % lower than that in meat-eaters, but due to the relatively small numbers of vegans in the cohort the CI of this estimate were wide and the difference was not statistically significant ( Reference Tong, Appleby and Bradbury 20 ) . The combined risk of IHD in vegetarians and vegans was 22 % lower than that in meat-eaters, and this was reduced to a 17 % lower risk after adjusting for BMI; data on lipids and blood pressure were not available for the whole cohort, but it is likely that the lower LDL-cholesterol and slightly lower systolic blood pressure of the vegetarians and vegans could explain the remainder of their lower risk.

In contrast to the lower risk of IHD, the risk of stroke was 17 % higher in vegetarians than that in meat-eaters, largely driven by a higher risk of haemorrhagic stroke, which was 48 % higher; the risk for total stroke was not attenuated by adjustment for BMI. The point estimate for haemorrhagic stroke in vegans compared to meat-eaters was 1⋅35, but this was not statistically significant. The cause of the higher risk of haemorrhagic stroke in vegetarians is not known, but it might be explained by the low LDL-cholesterol which has been associated with an increased risk in observational studies, Mendelian randomisation analyses and in lipid lowering trials using statins ( Reference Sun, Clarke and Bennett 21 , Reference Falcone, Kirsch and Acosta 22 ) ; it might also be related to other factors such as high homocysteine due to low vitamin B 12 , or possibly related to the low intake of animal protein, but further research is needed to examine these hypotheses.

The risk of diabetes in vegetarians in EPIC-Oxford was 35 % lower than that in meat-eaters ( Reference Papier, Appleby and Fensom 23 ) ; this was attenuated to 11 % lower and non-significant after adjusting for BMI at recruitment. The risk of diabetes in vegans was 47 % lower than that in meat-eaters, and this was attenuated to 1 % and non-significant after adjusting for BMI (there were only twenty-six cases among vegans) ( Reference Papier, Appleby and Fensom 23 ) . The interpretation of these findings is that vegetarians and vegans in this population have a substantially lower risk of diabetes compared to meat-eaters, which appears to be largely or entirely due to their lower BMI.

The risk for any type of cancer (all cancers combined) was 10 % lower in vegetarians than that in meat-eaters in EPIC-Oxford ( Fig. 1 ), and 18 % lower in vegans ( Fig. 2 ) ( Reference Key, Appleby and Crowe 24 ) . For specific cancer sites, the only differences in risk were for stomach cancer and haematological cancers, which were 62 and 36 % lower, respectively, in vegetarians, and cancer of the cervix which was 90 % higher in vegetarians, all with rather wide CI due to the relatively small numbers of cancers at individual sites. The risk for colorectal cancer did not differ between vegetarians and meat-eaters. The reasons for the observed differences are not well understood although there is some limited other evidence suggesting that processed meat may increase the risk for stomach cancer ( 25 ) . The higher risk of cancer of the cervix in vegetarians was unexpected and of borderline statistical significance; it is unlikely to be due to differences in screening, because reported attendance for cervical cancer screening does not differ between vegetarians and meat-eaters in the same cohort ( Reference Tong, Appleby and Bradbury 26 ) .

The lower risk for all cancers combined in both vegetarians and vegans than that in meat-eaters in EPIC-Oxford is interesting but needs to be interpreted very carefully because few associations with individual cancer sites have been identified and several common cancers, such as lung cancer, are very strongly associated with smoking and therefore, although the results are adjusted for smoking status, there could well be residual confounding by this or by other non-dietary factors. Further research is needed to clarify whether vegetarian diets may affect the risk for a range of cancers; vegan diets are of particular interest because they are associated with lower circulating concentrations of the growth factor insulin-like growth factor-I, high levels of which probably increases the risks for colorectal, breast and prostate cancer, and also because characteristics such as the amino acid profile of vegan diets may have other metabolic effects which could perhaps reduce cancer risk ( Reference Green, Lamming and Fontana 27 ) .

In EPIC-Oxford, the risk for a bone fracture at all sites combined was 11 % higher in vegetarians compared to meat-eaters, which was reduced to 9 % higher after adjustment for BMI because the vegetarians have a lower BMI and BMI is itself inversely associated with fracture risk at certain sites, particular at the hip ( Reference Tong, Appleby and Armstrong 28 ) . Larger differences were seen for hip fracture, for which vegetarians had a 34 % higher risk, reduced to 25 % higher after adjustment for BMI. In vegans, the risks for all fractures, before and after adjustment for BMI, were 50 and 43 % higher respectively, while the risks for hip fracture were 164 and 131 % higher, respectively. There was evidence of an interaction with BMI, since in vegans the risk for hip fracture was 3⋅17 (95 % CI 2⋅13, 4⋅71) among people with a BMI of less than 22⋅5 kg/m 2 but 0⋅94 (0⋅38, 2⋅29) among people with a BMI of 22⋅5 kg/m 2 and above ( P for heterogeneity = 0⋅041), although this was based on small numbers in the subgroups.

The reasons for the moderately higher fracture risk in vegetarians, and substantially higher risk in vegans, are not clear. For vegetarians, calcium intakes are adequate and similar to those in meat-eaters, so other explanations are needed. Vegans in EPIC-Oxford have relatively low intakes of calcium and low circulating vitamin D, but adjustment for dietary calcium had only a moderate attenuating impact on the raised risk, and in an earlier analysis in this cohort we saw no relationship of circulating vitamin D with fracture risk ( Reference Roddam, Neale and Appleby 29 ) . As noted earlier, the elevated risk of hip fractures was largely confined to people with a low BMI at recruitment (<22⋅5 kg m 2 ), and it is possible that greater weight loss into older age may contribute to the higher risk in vegans; there are also other possibilities such as the lower insulin-like growth factor-I we have observed in vegans ( Reference Allen, Appleby and Davey 30 – Reference Yakar, Werner and Rosen 32 ) , and the importance of nutrients such as calcium and protein may be underestimated in our analyses due to measurement error, a particular problem for calcium in vegans among whom a substantial amount may come from variably fortified foods.

In EPIC-Oxford, the linkage to hospital episode statistics data has enabled us to examine the risk of a range of other disorders in relation to the diet group. The risk of diverticular disease was observed to be 27 % lower in vegetarians and 72 % lower in vegans than that in meat-eaters, although the number of cases in vegans was only four ( Reference Crowe, Appleby and Allen 33 ) ; the lower risk in vegetarians and vegans (combined) was attenuated but remained statistically significant after adjusting for dietary fibre, suggesting that some of the lower risk is explained by fibre but that other factors such as meat itself may also contribute. The risk of gallstones did not differ between vegetarians and non-vegetarians ( Reference McConnell, Appleby and Key 34 ) , but obesity causes a large increase in the risk for this condition and, after adjustment for BMI, vegetarians were observed to have a relatively high risk compared to meat-eaters (22 % higher risk), suggesting that some characteristic of the vegetarian diet may have an adverse impact; there was evidence that high starch intake was associated with a higher risk, but this did not appear to explain the relatively higher risk of vegetarians after adjusting for BMI. The risk of kidney stones was 31 % lower in vegetarians than that in high meat-eaters, and the risk of cataracts was lower in both vegetarians and vegans than that in high meat-eaters, but the reasons for these apparent differences are not known ( Reference Turney, Appleby and Reynard 35 , Reference Appleby, Allen and Key 36 ) .

In comparison with regular meat-eaters, all-cause mortality did not differ in vegetarians (hazard ratio 1⋅00 (95 % CI 0⋅93, 1⋅08)) or in vegans (hazard ratio 1⋅14 (0⋅97, 1⋅35)) ( Reference Appleby, Crowe and Bradbury 37 ) . Although diet is one determinant of long-term health, there are many other factors including smoking status, alcohol intake and socio-economic factors, so all-cause mortality has to be interpreted carefully because non-dietary differences between groups, although adjusted for as far as possible, may still influence the results through residual confounding. Based on the available data, however, it appears that overall mortality from all causes combined is broadly similar in vegetarians and vegans compared to that in meat-eaters.

The strengths of EPIC-Oxford are its moderately large size, extensive exposure data with biological samples for about 30 % of participants and nearly complete follow-up for almost two decades through National Health Service datasets on cancer, hospital episodes and mortality. The main weaknesses are that, while the number of vegetarians is large enough to study the more common endpoints (about 20 000 vegetarians), the number of vegans in the study is too small (about 2500 vegans) to give accurate relative risk estimates, and that as with other epidemiological studies the measurements of dietary and other factors are subject to error.

Interpretation of the results requires care. As with all observational epidemiological studies, the classification of people by diet group is imperfect, and the estimates of relative risks are subject to potential confounding by other factors such as smoking status, alcohol intake and socio-economic factors; all the results reported are adjusted for these factors as far as possible, but this adjustment is never perfect due to errors in the assessment of exposure to these factors, therefore the results can be affected by residual confounding if an exposure such as smoking is strongly related to the disease of interest. Another potential problem in most nutritional epidemiological studies is reverse causation, where people may change their diet because of early effects of a yet undiagnosed condition on their health or appetite; it is not clear if this is an important problem in the results reported, but most of the vegetarians and vegans had followed their diet for several years at the time of recruitment and therefore their choice of diet is unlikely to be due to diseases which were on average diagnosed many years later.

Another important factor to consider when interpreting the findings is the role of BMI. Vegetarians and vegans in EPIC-Oxford have a lower mean BMI compared to meat-eaters, and high BMI is a well-established risk factor for a number of diseases, therefore it would be expected that this difference would cause a moderately lower risk of these conditions in those on plant-based diets; by contrast, for some sites of bone fractures and possibly for some other conditions, risk is higher in people with low BMI. When answering the question ‘what is the association of a plant-based diet with long-term health?’, we have generally taken the view that the plant-based diet itself is a major determinant of the lower BMI, and therefore that the most appropriate relative risks are those which are not adjusted for BMI (this is analogous to our interpretation of the role of LDL-cholesterol, where we do not adjust for this measure because it is almost certain that the differences in LDL-cholesterol between vegetarians, vegans and meat-eaters are caused by the composition of the diet). However, to fully understand the relationship of plant-based diets with health it is helpful to also consider the relative risks after adjustment for BMI, an approach which answers the question ‘for people of the same BMI, does health differ between meat-eaters and those on a plant-based diet?’.

A further point to consider when interpreting the results is that they are from comparisons with the non-vegetarians who joined the study and thus are determined by the healthiness of the comparison group. The participants in EPIC-Oxford were all recruited over the same period with the same methods, and the non-vegetarians have broadly similar characteristics to those of the vegetarians, such as similarly low rates of smoking and obesity. Thus the comparisons can be considered to be quite stringent, and both the vegetarians and the non-vegetarians in the cohort are generally healthier compared to the average for the UK population; during the first 9 years of follow-up the standardised mortality ratios of vegetarians and non-vegetarians were only about 40 % of the average for the UK ( Reference Key, Appleby and Davey 38 ) .

The plant-based diets of people in EPIC-Oxford who are vegetarians or vegans differ from those of meat-eaters, but for most nutrients the intakes of both groups are nutritionally adequate and meet or are close to meeting other government guidelines for good health, and many of the differences are quite small. Perhaps the most important potentially beneficial difference is the lower intake of saturated fat of those following plant-based diets and consequently their lower plasma LDL-cholesterol, which probably largely explains their lower risk of IHD. The higher intake of dietary fibre may also contribute to the lower risk of some disorders, particularly diverticular disease and possibly other disorders of the gastro-intestinal tract.

Potentially deleterious differences noted in people following plant-based diets are the lower average intakes and plasma concentrations of vitamin B 12 and vitamin D, and the lower average intake of calcium in vegans. Vitamin B 12 is of particular concern, since half the vegans studied had circulating concentrations indicating deficiency and this would be expected to have adverse effects on long-term health; for example, one possible explanation of the higher risk of stroke in vegetarians and vegans (combined) is that it is due to low vitamin B 12 leading to raised homocysteine and increased stroke risk, and more research is needed to investigate this relationship. Although not discussed in detail here, vegans also typically have low plasma concentrations of long-chain n -3 fatty acids, and low intakes of iodine unless they consume seaweed, fortified food, iodised salt or supplements. For all these nutrients, further research is needed to determine whether there are adverse effects on health endpoints and importantly whether any risks can be prevented by adequate food fortification and/or supplementation, for example for vitamin B 12 . Furthermore, the availability of plant-based foods, particularly substitutes for meat and fish, is expanding and their characteristics are evolving, therefore new studies are needed to examine the impacts of these changes; these should include examination of temporal changes in the consumption of these products, and ascertaining whether the dietary characteristics of people who have recently adopted a plant-based diet differ from those of people such as those in EPIC-Oxford who have followed such diets for a much longer period. Further research is required, and it would be ideal to recruit a large new cohort including tens of thousands of vegans, with the best available methods to measure diet, to eventually provide reliable evidence on their long-term health.

Acknowledgements

We thank all the participants in EPIC-Oxford and colleagues past and present at the Cancer Epidemiology Unit.

This study was supported by Cancer Research UK A29017; Medical Research Council MR/M012190/1; Wellcome Trust Livestock, Environment and People 205212/Z/16/Z.

The authors had sole responsibility for all aspects of preparation of this paper.

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• Volume 81, Issue 2
• Timothy J. Key (a1) , Keren Papier (a1) and Tammy Y. N. Tong (a1)
• DOI: https://doi.org/10.1017/S0029665121003748

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Plant-Based Diets

Researchers have shown that a more plant-based diet may help prevent, treat, or reverse some of our leading causes of death, including heart disease , type 2 diabetes , and high blood pressure . Interventional studies of plant-based diets have shown, for example, 90 percent reductions in angina attacks within just a few weeks. Plant-based diet intervention groups have reported greater diet satisfaction than control groups, as well as improved digestion, increased energy, and better sleep, and significant improvement in their physical functioning, general health, vitality, and mental health. Studies have shown plant-based eating can improve not only body weight, blood sugar levels, and ability to control cholesterol, but also emotional states, including depression, anxiety, fatigue, sense of well-being, and daily functioning.

Only one way of eating has ever been proven to reverse heart disease in the majority of patients: a diet centered around whole plant foods. If that’s all a whole-food, plant-based diet could do—reverse our number-one killer—shouldn’t that be the default diet until proven otherwise? The fact it may also be effective in preventing, treating, and arresting other leading killers seems to make the case for plant-based eating simply overwhelming.

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A Look at Plant-Based Diets

Introduction.

A high sugar, high fat, processed food-laden diet has contributed significantly to the burden of obesity and chronic disease in America. Not only do Americans consume fewer than the recommended daily servings of fruit and vegetables, but the average American eats approximately 200 pounds of red meat and poultry each year. 1 This volume is higher than needed to meet the average daily calorie and protein requirements of a healthy diet. According to recent data published by the Centers for Disease Control (CDC), just over 42% of Americans are obese. 2 Rates of obesity-related diseases such as cardiovascular disease, hypertension, and type 2 diabetes mellitus are at an all-time high. These common chronic diseases are known to be heavily impacted by diet and lifestyle. As a result, many people are looking to modify their diets for weight loss and improve their overall health.

Many Americans will go to extreme lengths to lose weight, as is evident from the proliferation of fad diets like the South Beach diet and the cabbage soup diet. Many physicians recommend plans such as the Mediterranean diet to help patients manage chronic comorbidities and pursue their health goals. Though perhaps less often recommended by physicians, a whole food, plant-based diet is another evidence-based option which can promote weight loss and ameliorate many so-called lifestyle diseases. Physicians need to understand the benefits and possible risks of alternative diets in order to effectively counsel patients on their adoption.

Plant-Based Diets Through the Ages

Throughout human history, different groups have adhered to plant-based diets. In ancient Greece, the philosopher Pythagoras extolled the health benefits of a vegetarian diet and taught that animal slaughter was immoral. This tenet was based on his belief that the immortal soul was reincarnated after death of the body. He and his disciples ate a simple diet of bread, honey, and vegetables. Thus, until the 1800s, a plant-based diet was known widely as the Pythagorean Diet. Many religions feature a long tradition of adhering to a vegetarian diet, including both Buddhism and Jainism. Much like Pythagoras’s followers, these religions approach the plant-based diet through the lens of nonviolence. In contrast, in the mid-1800s, the newly formed Seventh-Day Adventist Church advocated a vegetarian diet for its adherents, although its aim was to promote personal health and longevity rather than adhere to an ethical framework.

Today, plant-based eating continues to be popular. The number of Americans who follow a vegan diet increased 600% from 2014 to 2018. 3 Interest in plant-based diets is driven by a number of factors. Many choose a plant-based diet in the pursuit of health, out of concern for animal welfare, or as a way to reduce their environmental footprint. Some have also been driven in part by celebrity endorsement, media attention, and popular documentaries. Regardless of the reasons for their change, more Americans than ever are seeking to incorporate more plant-based foods into their diet.

As interest in plant-based diets has grown, so too has the market. Many restaurants are incorporating meat alternatives into their options, with some crafting and marketing dedicated plant-based menus. Items like the Beyond Burger ® are popular among vegans and meat-eaters alike. In grocery stores, plant-based egg, cheese, and milk alternatives have driven sales. The interest in plant-based alternatives is evident; the plant-based foods market has increased 29% in the U.S. between 2017 and 2019. 4

There are many benefits to consuming a diet high in fresh fruits and vegetables, one being better weight control. Multiple studies have linked plant-based diets to a lower BMI, and experimental data has shown that switching to a plant-based diet can help with weight loss. One example is a 16-week randomized control clinical analysis published in 2018. 5 This study assessed whether a diet void of animal protein and rich in plants would affect one’s body fat percentage, body mass index (BMI), and degree of insulin resistance. Participants were counseled not to change their physical activity level, and those in the control group continued their previous omnivorous diets. The findings demonstrated an association between eating plant-based protein and decreased BMI, lower visceral fat, and improved insulin resistance. 5 A systematic review published in January 2020 analyzing 40 diet- and weight-related case studies or cohort studies reported that those following a vegan diet were less likely than those following any other diet to be overweight and had lower BMIs. 6

Cardiac Health

In addition to helping improve insulin sensitivity and decrease BMI, a vegan diet may reduce risk of cardiovascular disease and improve cardiac function. This is of particular importance given that the CDC ranked heart disease as the leading cause of death in the United States in 2020. 7 There have been many studies that researched how a plant-based diet affects cardiovascular outcomes.

The Lifestyle Heart Trial examined the relationship between atherosclerosis and diet. In this study, patients with cardiac disease were switched from their standard omnivorous diets to either a plant-based diet or the American Heart Association Diet, which is the current standard of care dietary intervention. The study found that 34% more patients on the plant-based diet had reduction of atherosclerosis than those on the diet recommended by the American Heart Association. 8

A meta-analysis featuring seven prospective cohort studies reviewed heart health in vegetarians vs. omnivores. The analysis concluded that those who do not consume meat have significantly lower rates of both ischemic heart disease and all-cause mortality. 9

In a combined evaluation of five prospective analyses comparing omnivore vs. vegetarian rates of death from ischemic coronary disease, vegetarians were found to have 24% lower rates of death from ischemic heart disease than those who ate meat after controlling for factors such as smoking status, age, and gender. 10

A recent experimental study swapped amateur athletes’ omnivorous diets to a vegan diet and studied the athletes’ cardiac structure via echocardiogram prior to and following the diet. This study suggested that actual structural remodeling of the heart can occur when switching from an omnivorous diet to a plant-based diet. 11 This structural remodeling of the heart, albeit noted in healthy athletes, may play a role in the documented improvement of health in those with cardiovascular disease who adapt a plant-based diet.

Type II Diabetes Mellitus

Evidence suggests that a plant-based diet can help patients with type II diabetes achieve weight loss and improve glycemic control. The American Diabetes Association (ADA) Standards of Medical Care in Diabetes recognizes a plant-based diet as a viable option for patients with type II diabetes. 12 Multiple studies have shown an inverse relationship between a vegan diet and type II diabetes. 13 Research published in the Journal of Nutritional Medicine in 1994 studied 21 patients with type II diabetes who simultaneously changed to a diet free of animal products and began an exercise regimen. 14 Notable improvements included a decrease in triglycerides, total cholesterol, fasting blood glucose, and insulin resistance. Within two weeks, participants’ fasting blood glucose dropped an average of 35%, and five participants improved so much that they no longer required glucose-lowering medications. During long-term follow-up for four years, 17 out of the 21 patients had remained on the vegan diet and continued with an exercise program. These patients continued to have improved glycemic control.

The Many Variations of a Plant-Based Diet

Vegetarian: Also known as ovo-lactovegetarian, this diet includes all plant-based foods, as well as allowing eggs and dairy.

Vegan: This is a diet that consists of plant-based foods only and excludes meat, dairy, eggs, and often honey. Many who follow this lifestyle do so for ethical or environmental reasons, and other lifestyle modifications are typically included in addition to the dietary changes.

Pescatarian: This is a largely vegetarian diet that also includes seafood.

Whole-foods, plant-based (WFPB): Extremely similar to a vegan diet, this diet eschews the ethical baggage and focuses on the health aspect. High in fruit, vegetables and whole grains while typically low in fat.

Flexetarian: This is a broad term used by those who primarily follow a vegetarian or plant-based diet, but allow for some meat, dairy, and seafood on occasion.

Whereas meat consumption has been linked to an increased risk of developing diabetes, higher intake of fruits and vegetables has been shown to reduce the risk by as much as 50%. A prospective 10-year-long case-cohort study of over 300,000 individuals found an inverse relationship between the amount of fruits and vegetable servings eaten per day and risk of developing type II diabetes mellitus. 15 This research, published in BMJ in July 2020, found that increased produce intake was linked to higher levels of plasma vitamin C and carotenoids, markers of vegetable and fruit consumption, which was associated with decreased development of diabetes. Participants who developed diabetes over the course of the study had markedly lower biomarkers of fruit and vegetable intake than those who did not develop diabetes. Following a whole food plant-based diet, or simply increasing daily fruit and vegetable consumption, is one step individuals can take to reduce their risk of type II diabetes.

Hypertension

A meta-analysis and systematic review of 24 studies published between the years 1984 and 2019 was conducted to analyze the effect that dietary changes had on blood pressure in patients with type II diabetes. 16 The vegan diet was reviewed alongside other popular diets including the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet. All dietary changes were analyzed against a control, defined as patients making no dietary changes. The vegan diet, along with several others, was found to significantly lower both systolic and diastolic blood pressure.

A similar systematic review published in 2020 found that a vegan diet is associated with a significant decrease in blood pressure in those with hypertension (WMD = −3.118, 95% CI = −4.540, −1.696). 17 Those that followed either a vegetarian diet or a vegan diet reported decreases in blood pressure, although the decrease was more significant in those that followed a fully vegan diet. High blood pressure contributes to many other health complications and can compound the risks that those with diabetes already have. Hypertension is an independent risk factor for both heart disease and stroke; however, those with both diabetes and hypertension have the highest risk of fatal stroke. With more emphasis on dietary change, patients could see a substantial decrease in blood pressure while decreasing polypharmacy and the side effects that anti-hypertensive medications can provoke.

Dyslipidemia

Consumption of dietary cholesterol found in meat and dairy products contributes to atherosclerosis and heart disease. Since humans are capable of synthesizing all needed cholesterol, further dietary intake is not required for optimal function. A study published in May 2020 analyzed the correlation between meat consumption and low-density lipoprotein (LDL) levels in patients diagnosed with coronary artery disease. 18 The mean LDL level in the omnivorous group was found to be 34.75 points higher than the mean of the vegetarian group. Similarly, a large review of vegetarian diets and health outcomes, published in 2020, found there to be a clinically significant decrease in both total and LDL cholesterol levels in those who do not consume meat or fish products. 13 High levels of LDL are known to increase both the risk and severity of coronary artery disease including heart disease, angina, and myocardial infarction. Therefore, reducing dietary cholesterol by eliminating meat and dairy from one’s diet may represent one option to reduce risk of coronary disease.

Although many studies have been inconclusive as to whether or not vegetarian diets reduce risk of various specific cancers, some studies have suggested that eating processed meats such as ham, bacon, and salami pose an increased risk of developing cancer. In fact, the World Health Organization (WHO) classified processed meats as a Group 1 carcinogen and red meats as a Group 2 carcinogen. 19 Examination has also identified heme iron, the iron obtained by eating animal tissue, to be a risk factor for colorectal cancer. 20 Further recent research has suggested a dose-related effect between the amount of heme iron consumed and overall colorectal cancer risk due to heme-mediated DNA damage. A cohort study in 2006 of French women concluded that women whose diets were rich in meats had a greater likelihood of developing colorectal cancer than those who did not consume large amounts of red meat. 21 These studies suggest that plant-based diets may decrease modifiable risk factors for certain cancers.

Nutrient Content of a Plant-Based Diet

A plant-based diet is not always healthful. As the interest in plant-based eating has risen, so have the options for plant-based “junk food” such as donuts and cinnamon rolls. Imitation meat, milk, egg, and cheese products are typically lower in fat and calories than their animal product counterparts, but they are not necessarily nutritious. Attention must be paid to both the macro- and micro-nutrient content of any diet. A person could eat a diet that is plant-based yet high in sugar, saturated fats, and highly processed food products, thus negating some of the health benefits of a plant-based diet. A healthful plant-based diet is one composed of high-quality whole foods like grains, fruits, vegetables, legumes, nuts, and seeds.

A startling 95% of Americans are deficient in fiber, which is likely related to ingesting high amount of processed foods, yet little fruit, vegetables, legumes or whole grains. 22 A plant-based diet is by nature high in fiber, whereas animal products are devoid of fiber. All dietary sources high in fiber, such as beans, broccoli, berries, avocados, and apples, are plant-derived. Sufficient fiber intake is protective against insulin resistance, hypertension, cancer, gastrointestinal disease, obesity, heart failure and digestion-related disorders. 23 The small proportion of Americans who have adequate fiber intake are nearly all vegetarian or vegan, and incorporation of more plant foods into the standard American diet could help provide some mitigation against common chronic diseases.

While a plant-based diet is rich in many micronutrients that are missing from the standard American’s diet, care should be taken with any diet to ensure adequate intake of all vital nutrients. When considering a plant-based diet, the first component many people think about is protein. While most people equate protein with meat, dairy, and eggs, many plant foods contain high amounts of protein as well. Brown rice, quinoa, beans, and legumes can be added as part of a plant-based diet to ensure adequate intake of all essential amino acids. Americans tend to prioritize protein, but according to the Institute of Medicine, only 10% to 35% of daily of calorie intake needs to be from protein. 24 Most people have no issue meeting this goal. If protein is a concern, a plant-based diet can be augmented with increased content of high-protein plant foods. For those with high protein goals such as athletes, plant-based protein supplements are widely available.

Micronutrients

One micronutrient that often raises concern in a plant-based diet is vitamin B12. Some studies have shown that those on a plant-based diet are found to have lower plasma vitamin B12 levels and higher levels of vitamin B12 deficiency than those who consume animal products. 6 Vitamin B12 is an important cofactor in DNA synthesis, and deficiency can lead to anemia and severe neurological dysfunction. It is especially critical that pregnant persons ensure adequate Vitamin B12 levels, as a deficiency can lead not only to neural tube defects, but long-term consequences in weight management and brain development affecting the unborn child past delivery into its adulthood. 25

Vitamin B12 is created by bacteria in the soil. Due to current food processing procedures removing this bacteria, vitamin B12 is primarily obtained by consuming meat products. Fortunately, many modern foods, like breakfast cereals and nondairy milks, are fortified with vitamin B12. In addition, vitamin B12 supplements are widely available and commonly found at health food stores and pharmacies. Some evidence suggests that vegans are also at risk for deficiencies of other micronutrients, including selenium, zinc, niacin, vitamin B2, vitamin B6, and calcium. 6 Supplementation of vitamin B12 and other micronutrients is one way to ensure adequate intake and reduce the risk for developing deficiency while on a plant-based diet. However, a German study published in 2020 compared serum levels of micronutrients of 36 omnivores and 36 vegans and found that there was no significant difference in vitamin B12 levels between the two groups. This suggests that eating a variety of fortified foods and taking a supplement is sufficient for obtaining normal vitamin B12 levels. 26

Unresolved Issues

Recently published research has identified other potential risks of a plant-based diet which deserve further study. Whereas older studies have shown that persons following a plant-based diet have lower bone mineral density (BMD) than those who eat meat, evidence published in late 2020 suggests that fracture risk may be higher as well. 27 Some, but not all of this increased risk was accounted for by differences in BMI, as obesity may be protective against fracture at certain sites. However other recent research, including a recent meta-analysis, failed to show an association between increased dairy intake and prevention of fractures. 28 Therefore, it is unclear whether a plant-based diet – devoid of dairy – would increase fracture risk. Regardless, it is prudent for those on a plant-based diet to ensure sufficient intake of calcium- and vitamin D-containing foods. Careful attention to intake of fortified foods, such as plant-based milks, may be helpful.

According to another recent study published in the British Medical Journal, hemorrhagic stroke was cited as a risk for vegetarians and vegans. 29 This study compared the rates of stroke between meat eaters, pescatarians, and vegetarians, and found a statistically significant increase in hemorrhagic stroke in vegetarians compared to meat eaters. Their research found that vegetarians had “three more cases of total stroke (95% confidence interval 0.8 to 5.4 more) per 1,000 population over 10 years.” However, it was found that risk of mortality from stroke was not significantly higher or lower in vegetarians compared to meat eaters. This study also did not differentiate results between those eating dairy and eggs and those following purely plant-based diets due to the small number of vegans enrolled. It is postulated that a low level of LDL, which is found primarily in animal products, may lead to increased risk of hemorrhagic stroke. 30 Although the study was informative, these results of increased stroke risk have not been corroborated by further studies. This same study found that vegetarians, including vegans, had lower rates of myocardial infarction, ischemic heart disease, obesity, high cholesterol, hypertension, and diabetes.

As millions of Americans continue to struggle with obesity, diabetes, and cardiovascular disease, many continue to seek healthier alternatives to the typical American diet. According to an expansive review published in 2020, plant-based diets “were associated with a significantly reduced risk of negative health outcomes with a pooled ES of 0.886 (95% CI: 0.848 to 0.926; P < 0.001) without significant heterogeneity (I 2 = 43.16%; 95% CI: 3.55 to 66.51; P = 0.02).” 13 Given that so many health conditions and adverse outcomes can be mitigated by a plant-based diet, and that there is rapidly-growing public interest in this diet, physicians need to be educated and ready to counsel their patients on the benefits and risks of a plant-based diet. A well-planned diet of plant-based whole foods incorporating a variety of vegetables, whole grains, nuts, and legumes can be one tool to help physicians and patients address the chronic lifestyle diseases with which many struggle.

Patients with chronic health conditions who adhere to this diet may expect to see weight loss, improvement in blood pressure and cholesterol, and reduced risk of heart disease. Care should be taken to include a variety of fruits, vegetables, seeds, nuts, and legumes to ensure adequate consumption of protein. Vitamin B12 and calcium can be found in fortified foods or added via supplementation to ensure adequate intake. Organizations like the American Heart Association and Academy of Nutrition and Dietetics now recognize that a well-planned plant-based diet is healthy and safe for most adults. Physicians should feel confident recommending such a diet to their patients and supporting this choice when a patient expresses interest.

Julia Clem, MD, is a graduate of University of Missouri–Kansas City School of Medicine (UMKC SOM) and is now a Family Medicine Resident at the Indiana University School of Medicine, Indianapolis, Indiana. Brandon Barthel, MD, (above), is Assistant Professor of Medicine in Internal Medicine and Endocrinology, Truman Medical Center at UMKC SOM.

None reported.

10 Benefits of a Plant-Based Diet

One of the easiest ways you can start improving your overall health is by going plant-based. From your gut to your heart and brain, nearly every part of your body benefits when you add more fruits, vegetables, nuts, seeds and legumes to your plate.

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Keep in mind that following a plant-based diet doesn't mean you have to be vegetarian or vegan if you love foods like Greek yogurt, cheese or fish.

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"A plant-based eating pattern may or may not include animal products, but the frequency of animal product consumption and the portion sizes of animal products are smaller than the conventional American diet," Kelly Jones, RDN, CSSD , explains. By including more whole plant foods, you'll get more vitamins, minerals, antioxidants and fiber.

"Incorporating a plant-based lifestyle actually helps people increase variety in their diet," Jones says. "People become more adventurous with vegetables and legumes they've never tried or never given a second chance, and begin adding more flavor, spices and even a greater variety of cuisines into their regular eating pattern."

And don't worry, you'll get enough protein: "Standard portions of proteins, animal-based or not, tend to be much larger than what the body needs for optimal function — and many people don't recognize the protein available from grains, vegetables, nuts and seeds all add up in meals and snacks," Jones says.

So start adding a few animal-free foods to your diet every day — remember, you don't have to overhaul your eating habits all at once — to begin reaping these plant-based diet benefits.

1. It’s Good for Your Gut

"Plant-based diets tend to better support gut health and the microbiome, which science is continuing to tell us impacts many areas of health — from immune system function to metabolism and mood," Jones says.

This is largely due to the fiber and antioxidants, compounds that protect your cells from damage, found in plants. "Since plant foods are the only source of fiber and fermentable carbohydrates known as prebiotics‌ , ‌ and they offer tens of thousands of phytochemical antioxidants, the bacteria in the lower digestive tract are better supported when diets are rich in whole plant foods," Jones says.

Your digestive system is home to about 100 trillion bacteria (both good and bad!), and while everyone has a unique microbiota, certain collections of bacteria are known to be found in healthy people, per Harvard Medical School .

The latest research suggests that certain healthy gut bacteria are linked to lower susceptibility to rheumatoid arthritis and offer a possible treatment or prevent inflammation that contributes to fatty plaque build-up in arteries.

"One of the most fascinating areas of nutrition to me is how it impacts mental health, and studies have shown vegetarian and vegan diets to reduce psychological distress and reports of anxiety, depression and fatigue."

2. It Supports Your Immune System

"Eighty percent of our immune system is in our gastrointestinal tract, and it's good for the immune system to have a healthy microbiome ," says Lauren Graf, RD . "The best way to do that is to feed the good bacteria. A lot of the fiber found in plant foods like bananas and artichokes serves as prebiotics, which are food for probiotics."

Plant foods are also filled with nutrients that can help strengthen your immune system. Just a few of the many helpful vitamins and minerals found abundantly in fruits and vegetables include:

• ‌ Vitamin C: ‌ A 200-milligram daily dose vitamin C appeared to shorten the duration of cold symptoms by 8 percent in adults and 14 percent in children, which equates to about one day less of sickness, per a January 2013 review in the ‌ Cochrane Database of Systematic Reviews . ‌ One large bell pepper contains 233 milligrams of vitamin C.
• ‌ Vitamin E: ‌ Found in high-fat plant foods like peanuts, sunflower seeds, hazelnuts and almonds, vitamin E is part of nearly 200 biochemical reactions in your body and acts as an antioxidant to helps your body fight infection, per the Cleveland Clinic .
• ‌ Zinc: ‌ This mineral has antiviral properties and is found in plant foods such as beans, nuts and whole grains. It has well-established effects on the immune system and even has the potential to be a supportive treatment in people with COVID-19, per an August 2020 review in ‌ Maturitas ‌ . A zinc deficiency can result in immune dysfunction and increase your susceptibility to infection.
• ‌ Vitamin A: ‌ Known as an infection fighter, you can get vitamin A from both animal sources and plant carotenoids. Aim for colorful plant foods like carrots, sweet potatoes, butternut squash, pumpkin, cantaloupe and dark green leafy vegetables, the Cleveland Clinic recommends.

3. It Helps Lower Inflammation

You've likely seen powders and potions that tout antioxidant and anti-inflammatory benefits, but it's really best to get your antioxidants through a plant-based diet.

"When we get our nutrients from whole foods, they tend to be more bioavailable than supplements," Maya Feller, RD, CDN , says. "Plus, when we eat whole foods, in general, we don't worry about toxicity."

Antioxidants are important because they can prevent or delay some types of cell damage. While diets high in vegetables and fruits (great sources of antioxidants) have been found to be healthy, research has not shown that antioxidant supplements are beneficial in preventing disease, per the National Institutes of Health (NIH).

Your body naturally forms free radicals — highly unstable molecules that can cause oxidative stress, a process that leads to cell damage — when you exercise, digest food, smoke or are exposed to sunlight or air pollution, according to the NIH. This oxidative stress is believed to play a role in a variety of diseases such as cancer, heart disease, diabetes, Alzheimer's disease, Parkinson's disease and even eye disease like age-related macular degeneration and cataracts.

"When we think about lowering inflammation with a plant-based diet, it really leads back to gut health," Feller says. "The gut is involved in managing inflammatory properties, and plants have fiber, polyphenols and phytonutrients that all help with reducing inflammation."

4. It Helps You Maintain a Healthy Weight

A large body of evidence shows that fruits and vegetables can help you lose weight .

Eating more vegetables and fruits promotes long-term weight stability or weight loss in women, per a June 2020 review in ‌ Nutrients ‌ . This may be because the fiber in fruits and vegetables helps you to feel satiated faster and because veggies and fruit are low in fat and calories. (It's worth noting that the Hass Avocado Board funded this review, but it's still notable because it specifically looked at how higher vegetable and fruit intake affects weight loss largely in women — and was the first review to do so.)

The review included one prospective study that found the top five fruits for weight loss were blueberries, apples, pears, prunes, strawberries and avocados. Meanwhile, the top five non-legume vegetables for weight loss were broccoli, peppers, summer squash, cauliflower and Brussels sprouts.

What's more, shifting to a plant-based, low-fat diet is linked to increasing the body's metabolism to the point of reducing excess body fat, per a November 2020 study in ‌ JAMA Network Open . ‌ By the end of the trial, the plant-based group had an average 18.7-percent increase in after-meal calorie burn and a lost about 18 pounds, as well as saw a decrease in insulin resistance and body fat — particularly visceral fat, a dangerous type of fat stored around internal organs.

The U.S. Centers for Disease Control and Prevention (CDC) recommends eating more fruits and vegetables as a healthy way to lose or maintain weight. The water and fiber in fruits and vegetables add volume, so you can eat the same amount of food for fewer calories (while still feeling satiated!) when you focus on produce.

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5. It Keeps Your Heart Healthy

Going plant-based helps you replace unhealthy saturated and trans fats with plant-based fats that contain heart-protective polyunsaturated and monounsaturated fats, Feller says.

And while limiting animal foods can reduce your cholesterol levels, eating more fiber — particularly soluble fiber — actually helps to bind with cholesterol in our gut and pull it out of our bodies, Graf says. "It naturally lowers your cholesterol."

A plant-based diet is tied to a lower risk of diabetes, and diabetes and heart disease often go hand in hand, per the CDC . If you have diabetes, you are twice as likely to have a stroke or heart disease than someone without diabetes (and at a younger age). You're also more likely to have heart disease the longer you have diabetes.

"One thing that a lot of people are surprised by is that plant-based diets are very effective for preventing or reversing insulin resistance," Graf says. "When we look at real clinical trials of people following plant-based diets versus higher-fat animal diets, consuming beans, whole grains, vegetables, fruits, nuts and seeds seems to lower insulin resistance, hemoglobin A1C levels [a measure of sugar in the blood] and your risk for developing type 2 diabetes."

These studies explore the link between conditions involved in heart health and a plant-based eating plan:

• ‌ Blood pressure: ‌ A plant-based diet packed with vegetables and whole grains and limited in refined grains, sugary drinks and meat is linked to lower systolic and diastolic blood pressure levels, per a July 2020 study in the BMJ .
• ‌ Diabetes: ‌ People who adhered more strictly to plant-based diets were observed to have a lower risk of type 2 diabetes than those who did so less strictly in a July 2019 meta-analysis of more than 300,000 participants in ‌ JAMA Internal Medicine ‌ .
• ‌ Cholesterol: ‌ A November 2020 study in ‌ Heart ‌ found that people with obesity (the majority were men) who followed a "green" Mediterranean diet, with plant-based foods replacing meat and fish, had lower cholesterol levels and lost up to 13.6 pounds more than those eating meat on the diet. They also had lower blood pressure.
• ‌ Heart disease: ‌ Researchers used data from 12,168 middle-aged adults who were followed up with from 1987 through 2016 to track the effect of their diets on long-term health in an August 2019 study in ‌ Journal of the American Heart Association ‌ . Those who best adhered to an overall plant-based diet or pro-vegetarian diet were observed to have a 16-percent lower risk of cardiovascular disease, 31- to 32-percent lower risk of cardiovascular disease mortality and 18- to 25-percent lower risk of all-cause mortality than those with the least adherence.

6. It's Linked to a Reduced Risk of Cancer

Eating many plant-based foods has been linked with lower cancer rates, likely because plants produce protective phytochemicals that are anti-inflammatory — plus, they help you eat more fiber, per the Mayo Clinic .

Diets rich in both soluble and insoluble fiber were linked to a lower risk of getting breast cancer before menopause compared to lower-fiber diets, per a March 2016 study published in ‌ Pediatrics ‌ ‌ . ‌

Meanwhile, every 10 grams of fiber daily is linked to a 10-percent reduced risk of colon cancer, according to a November 2011 study in the ‌ BMJ ‌ ‌ . ‌

7. It Benefits Your Brain

A healthy plant-based diet is linked to a lower risk of stroke, according to a March 2021 study in ‌ Neurology ‌.

And researchers found that the Mediterranean-Dash Intervention for Neurodegenerative Delay (MIND) diet is linked to a lower risk of Alzheimer's Disease by up to 53 percent in those who adhere to the diet rigorously and by 35 percent in those who stick to it moderately well, per a February 2015 study in ‌ Alzheimer's & Dementia ‌ ‌ . ‌

The MIND diet emphasizes brain-healthy food groups, which are largely plant-based. It also outlines five unhealthy groups to limit, including red meats, butter and cheese.

"Plant-based diets are linked to better brain health, especially as we age," Jones says. "The MIND diet is very rich in plants with a very small inclusion of animal products, and is well-researched to have an association with improved neurological function and reduced risk of Alzheimer's disease."

A plant-based diet may also be able to influence brain function — though the exact mechanisms are still unclear and more research is needed, per a September 2019 review in ‌ Translational Psychiatry ‌ ‌ . ‌

"One of the most fascinating areas of nutrition to me is how it impacts mental health, and studies have shown vegetarian and vegan diets to reduce psychological distress and reports of anxiety, depression and fatigue," Jones says.

"The Mediterranean diet is one of the most popular plant-based diets and also has links to reductions in depression, anxiety and stress despite the inclusion of fish and very small amounts of meat and poultry."

8. You'll Have More Energy

Plant-based foods are beneficial for your digestive system in several ways, which may help you feel more energized and satiated throughout the day.

"An increase in nourishing carbohydrates, vitamins, minerals and antioxidants — as well as the decrease in saturated fat and heavy animal proteins — can leave people feeling lighter, more energetic and with an improved mood," Jones says.

What's more, although many fad diets emphasize excluding carbs , it's the type of fuel your body prefers.

"In meat-heavy American diets, fat and protein tend to be ingested in higher amounts than needed, so smaller percentages of energy come from carbs," Jones says. "While this may sound in line with some trendy diets, carbs are the most efficient and preferred source of energy for the muscles and the central nervous system. Shifting to a more plant-based diet increases intake of the usable energy that our bodies thrive off."

"We also think of antioxidants as beneficial for long-term health, but in the short term, they work synergistically with each other as well as with our macronutrients, vitamins and minerals to support our metabolism, reduce inflammation and play a role in immune function. This can in turn improve energy levels and mental clarity," Jones adds.

Plant-based diets help improve blood thickness, helping more oxygen reach the muscles and improving athletic performance, per a January 2019 review in ‌ Nutrients ‌ ‌ . ‌ They also improve arterial flexibility and diameter to lead to better blood flow while a single high-fat meal can impair arterial function for several hours.

You may not even realize how sluggish you're feeling until you make the shift to a plant-based diet. "When you're eating food that's easier for our body to break down, I believe that can improve energy levels," Graf says. "Sometimes, people will say they didn't realize how bad they were feeling or how much better they could feel until they changed their habits."

9. It's Linked to a Lower Risk of Osteoporosis

More research is needed, but some theoretical findings suggest that a long-term plant-based diet is associated with lower rates of osteoporosis, per an August 2020 review in ‌ Current Opinion in Endocrinology, Diabetes and Obesity ‌ .

There's also no evidence that a plant-based diet, when followed carefully to maintain adequate calcium and vitamin D levels, has negative effects on bone health.

10. It's Tied to a Lower Risk of Kidney Disease

Although there were once concerns about protein and amino acid deficiencies with plant-based proteins in people with chronic kidney disease (CKD), those were debunked years ago.

A March 2019 paper in the ‌ Journal of Renal Nutrition ‌ concluded that not only can you eat a plant-based protein diet if you have chronic kidney disease, but it may even improve your condition.

"Those substituting animal-based proteins for plant-based proteins have shown reductions in severity of hypertension [high blood pressure], hyperphosphatemia [an electrolyte disorder] and metabolic acidosis [an accumulation of acid in the body]," note the researchers.

9 Plant-Based Product Swaps for Your Go-To Foods, From Cheese to Yogurt to Eggs

• Harvard Medical School: "Can gut bacteria improve your health?"
• Harvard Medical School: "Should I be eating more fiber?"
• Mayo Clinic: "Chart of high-fiber foods"
• Cochrane Database of Systematic Reviews: "Vitamin C for preventing and treating the common cold"
• Cleveland Clinic: "8 Vitamins & Minerals You Need for a Healthy Immune System"
• Maturitas: "Immune-boosting role of vitamins D, C, E, zinc, selenium and omega-3 fatty acids: Could they help against COVID-19?"
• National Institutes of Health: "Antioxidants: In Depth"
• Nutrients: "A Comprehensive Critical Assessment of Increased Fruit and Vegetable Intake on Weight Loss in Women"
• JAMA Network Open: "Effect of a Low-Fat Vegan Diet on Body Weight, Insulin Sensitivity, Postprandial Metabolism, and Intramyocellular and Hepatocellular Lipid Levels in Overweight Adults"
• U.S. Centers for Disease Control and Prevention: "Using Fruits & Vegetables to Manage Your Weight"
• U.S. Centers for Disease Control and Prevention: "Diabetes and Your Heart"
• Journal of Hypertension: "The effect of plant-based dietary patterns on blood pressure a systematic review and meta-analysis of controlled intervention trials"
• National Institutes of Health: "DASH Eating Plan"
• JAMA Internal Medicine: "Association Between Plant-Based Dietary Patterns and Risk of Type 2 Diabetes"
• Heart: "The effect of green Mediterranean diet on cardiometabolic risk; a randomised controlled trial"
• Journal of the American Heart Association: "Plant‐Based Diets Are Associated With a Lower Risk of Incident Cardiovascular Disease, Cardiovascular Disease Mortality, and All‐Cause Mortality in a General Population of Middle‐Aged Adults"
• Pediatrics: "Dietary Fiber Intake in Young Adults and Breast Cancer Risk"
• The BMJ: " Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies"
• Current Opinion in Endocrinology, Diabetes and Obesity: "Plant-based diets and bone health: sorting through the evidence"
• Journal of Renal Nutrition: "Adequacy of Plant-Based Proteins in Chronic Kidney Disease"
• Alzheimer's & Dementia: "MIND Diet Associated with Reduced Incidence of Alzheimer’s Disease"
• Translational Psychiatry: "The effects of plant-based diets on the body and the brain: a systematic review"
• Nutrients: "Plant-Based Diets for Cardiovascular Safety and Performance in Endurance Sports"
• USDA: "Sweet Red Bell Peppers"
• BMJ: "https://nutrition.bmj.com/content/early/2020/07/07/bmjnph-2020-000077"
• Neurology: "Quality of Plant-based Diet and Risk of Total, Ischemic, and Hemorrhagic Stroke"

Ever Struggled to Stick With Plant-Based Eating? The Reason Why Might Lie in Your Genes

People might assume that dietary choices come down to willpower. But that's not necessarily the case, particularly when it comes to eating vegetarian and vegan. A study published last fall in the journal PLOS One found that it might actually be our genes  that strongly influence our ability to strictly adhere to a vegetarian lifestyle.

How your genes can influence vegetarian and vegan eating

Published in October of 2023, the study conducted by Northwestern University’s Medicine program is the first to examine the role of genetics in someone’s ability to be a strict vegetarian. This objective came about as researchers pondered how many vegetarians in their lives still ate meat, poultry, and fish. Given that there are other genetically-determined things that can play into dietary choices 2 (including a person's metabolism and taste preferences), the researchers wondered if there was something in our genes that affected how well someone took to vegetarianism.

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Researchers utilized data from the UK Biobank (a large-scale biomedical database), comparing the genetic profiles of 5,324 vegetarians who ate no meat, fish, or poultry to 329,455 control subjects. All subjects were taken from a homogenous sample of white Caucasian background to avoid ethnicity-related variables that might impact the results.

"It seems there are more people who would like to be vegetarian than actually are, and we think it’s because there is something hard-wired here that people may be missing." —Nabeel Yaseen, MD, PhD

Researchers found that there were three genes significantly associated with strict vegetarianism (and another 31 that had potential association). Two of the three significant genes were tied to fat metabolism and brain function within the body—making researchers hypothesize that how people metabolize fats plays a role in whether or not they're able to stick with vegetarianism. "Lipid profiles of foods from animal sources are significantly different from those of plant sources," the study authors wrote. Individuals with these specific “vegetarian” genes may be able to synthesize these lipid components internally without eating meat, the researchers hypothesized. Meanwhile, people without this genetic profile may need to eat meat-based products to obtain these essential fats, and thus would crave meat more significantly if they went without.

Caveat incoming: This is just the first study to make this potential connection. Lots more research needs to be done, particularly on people of different ethnic backgrounds, to know more definitively whether these three genes do play a role in vegetarianism. But there's lots of interesting potential here to explore—and the results might bring some peace of mind to people who may feel guilty for having to give up their plant-based ways.

"It seems there are more people who would like to be vegetarian than actually are, and we think it’s because there is something hard-wired here that people may be missing," corresponding study author Nabeel Yaseen, MD, PhD , shared in a press release about the study.

Other factors that contribute to plant-based eating

Of course, your genetics aren't everything. There are many other social and cultural reasons why someone may opt for a vegetarian or plant-based lifestyle, DNA be damned:

Religion and culture

There are cultures and religions across the globe where vegetarianism is a core tenant of daily life and practice. For example, Rastafarians in Jamaica follow a vegetarian diet by eating what they call Ital food : no salt, oil, and meat, and instead having lots of natural foods from the Earth. A whopping 24 percent of the Indian population is vegetarian, thanks to many of the prominent religions in the country that prioritize plant-based eating like Buddhism, Hinduism, and Jainism. But these examples are just scratching the surface, as several other religions and cultures across nearly every continent place importance on following a plant-based diet.

Environment and ethics

As concern surrounding climate change and animal welfare grows, so do commitments to eating fewer (or zero) meat-based products. This is partially related to the at least 14.5 percent of all global greenhouse gas emissions tied to raising livestock for meat. Another study found that global greenhouse gas emissions from animal foods are double that of plant-based foods 3 . Plus, many of the concentrated farming operations that pump out high volumes of animals for meat production are notorious polluters of local air and waterways through the dumping of chemicals, animal waste, and more. This negatively impacts the health of the surrounding communities and ecosystems.

On the ethics front, a staggering 80 billion animals are killed each year to meet the growing demand for meat products. Many animals, particularly those sourced from large-scale factory farm operations, are subject to cruel treatment during their short lifespans before being killed for meat. Workers in the meat processing and packing industries are also treated inhumanely 4 : paid low wages, subject to serious injuries , psychological distress 5 , and minimal protections. For many animal lovers, these realities have driven them towards a more plant-based lifestyle.

And finally, we have health which is possibly the most popular reason why more and more people are reaching for meat alternatives. In fact, plant-based eating has been linked to reduced risk for heart disease 6 , cancer 7 , type 2 diabetes 8 , and kidney disease 9 . (It's also associated with improved gut health 10 .)

One main through line on how a vegetarian lifestyle yields all these health benefits is through its general reduction of inflammation throughout the body. This is thanks to its generally boosted fiber, vitamin, mineral, and plant compound content. But on the other side of the coin, if plant-based diets aren’t practiced intentionally, they can put followers at risk for deficiencies in key vitamins and minerals that are harder to get from plants (like iron and vitamin B12 ).

The bottom line

Yes, scientists have found some genetic factors that might potentially make it easier for some people (and harder for others) to strictly follow a vegetarian diet. But there are so many other social and cultural elements at play that can override (or make less important) what's written in your DNA. If you want to eat less meat but can't quite fully go cold turkey (so to speak), the flexitarian way might be up your alley.

It’s also important to note that no one way of eating is going to be superior for everyone . If you strictly follow a plant-based lifestyle, that is wonderful. But if you don’t, take it from this dietitian: There’s no need to worry or feel shame. Any way of eating should still prioritize variety through including lots of different fruits, vegetables, nuts, seeds, legumes, whole grains, herbs, and spices to provide a wide array of nutrients.

Regardless of whether you’re plant-based or not (and your reasons why), embracing moderation and balance in both lifestyles is paramount to overall wellness.

• Yaseen, Nabeel R et al. “Genetics of vegetarianism: A genome-wide association study.” PloS one vol. 18,10 e0291305. 4 Oct. 2023, doi:10.1371/journal.pone.0291305
• Smith, Andrea D et al. “Genetic and environmental influences on food preferences in adolescence.” The American journal of clinical nutrition vol. 104,2 (2016): 446-53. doi:10.3945/ajcn.116.133983
• Xu, Xiaoming et al. “Global greenhouse gas emissions from animal-based foods are twice those of plant-based foods.” Nature food vol. 2,9 (2021): 724-732. doi:10.1038/s43016-021-00358-x
• Winders, Delcianna J, and Elan Abrell. “Slaughterhouse Workers, Animals, and the Environment: The Need for a Rights-Centered Regulatory Framework in the United States That Recognizes Interconnected Interests.” Health and human rights vol. 23,2 (2021): 21-33.
• Slade, Jessica, and Emma Alleyne. “The Psychological Impact of Slaughterhouse Employment: A Systematic Literature Review.” Trauma, violence & abuse vol. 24,2 (2023): 429-440. doi:10.1177/15248380211030243
• Satija, Ambika et al. “Healthful and Unhealthful Plant-Based Diets and the Risk of Coronary Heart Disease in U.S. Adults.” Journal of the American College of Cardiology vol. 70,4 (2017): 411-422. doi:10.1016/j.jacc.2017.05.047
• DeClercq, Vanessa et al. “Plant-Based Diets and Cancer Risk: What is the Evidence?.” Current nutrition reports vol. 11,2 (2022): 354-369. doi:10.1007/s13668-022-00409-0
• McMacken, Michelle, and Sapana Shah. “A plant-based diet for the prevention and treatment of type 2 diabetes.” Journal of geriatric cardiology : JGC vol. 14,5 (2017): 342-354. doi:10.11909/j.issn.1671-5411.2017.05.009
• Adair, Kathleen E, and Rodney G Bowden. “Ameliorating Chronic Kidney Disease Using a Whole Food Plant-Based Diet.” Nutrients vol. 12,4 1007. 6 Apr. 2020, doi:10.3390/nu12041007
• Craig, Winston J et al. “The Safe and Effective Use of Plant-Based Diets with Guidelines for Health Professionals.” Nutrients vol. 13,11 4144. 19 Nov. 2021, doi:10.3390/nu13114144

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• DOI: 10.3897/biss.7.110699
• Corpus ID: 260792047

Improving Collection-Based Biodiversity Research in Chile: Digitisation and implementation of web portals

• Ricardo A. Segovia , P. Guerrero , +1 author J. Saez
• Published in Biodiversity Information… 8 August 2023
• Environmental Science, Biology, Computer Science

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