Aplant-based diet is adiet consisting mostly or entirely ofplant-based foods.^[1][2] It encompasses a wide range of dietary patterns that contain low amounts of animal products and high amounts offiber-rich^[3] plant products such asvegetables,fruits,whole grains,legumes,nuts,seeds,herbs, and spices.^[4][5][6] Plant-based diets may also bevegan orvegetarian but do not have to be,^[7][8] as they are defined in terms of high frequency of plants and low frequency of animal food consumption.^[4][7]

Origin of the term "plant-based diet" is attributed toCornell University nutritionalbiochemistT. Colin Campbell who presented his diet research at theUS National Institutes of Health in 1980.^[9][10] Campbell's research about a plant-based diet extended fromThe China Project, a decade-long study of dietary practices in rural China, giving evidence that a diet low in animal protein and fat, and high in plant foods, could reduce the incidence of several diseases.^[11] In 2005, Campbell and his son publishedThe China Study, abest-selling book emphasizing the potential health benefits of a plant-based diet.^[9][12] Campbell also used the plant-based concept to educate consumers about how eating meat had significant environmental consequences.^[9]

Some authors draw a distinction between diets that are "plant-based" or "plant-only".^[13] A plant-based diet may be defined as consuming plant-sourced foods that are minimally processed.^[9][12]

A review analyzing the use of the termplant-based diet in medical literature found that 50% of clinical trials use the term interchangeably with vegan, meaning that the interventional diet did not include foods of animal origin. 30% of studies included dairy products and 20% meat.^[14]

In 2021, theWorld Health Organization (WHO) stated that "plant-based diets constitute a diverse range of dietary patterns that emphasize foods derived from plant sources coupled with lower consumption or exclusion of animal products. Vegetarian diets form a subset of plant-based diets, which may exclude the consumption of some or all forms of animal foods."^[15] The WHO listsflexitarian,lacto-vegetarian,lacto-ovo vegetarian,ovo-vegetarian,pescatarian and vegan diets as plant-based.^[15]

A 2023 review paper defined plant-based as "a dietary pattern in which foods of animal origin are totally or mostly excluded".^[1]

In 2024, theInternational Organization for Standardization drafted ISO 8700 on "Plant-based foods and food ingredients - Definitions and technical criteria for labelling and claims".^[16]

As of the early 21st century, some 4 billion people are estimated to live primarily on a plant-based diet, some by choice and some because of limits caused by shortages of crops, fresh water, and energy resources.^[17] Main motivations to follow a plant-based diet appear to be health aspirations, taste, animal welfare, environmental concern, and weight loss.^[18] In the U.S.A., people takeindividual action on climate change through their diet. Twenty-six per cent of those who eat a plant-based diet because they are "alarmed" about global warming — defined by the Yale Program on Climate Change Communication as those who are "convinced global warming is happening, human-caused, an urgent threat" — and twenty-seven per cent eat a plant-based diet because they are "concerned" — they believe global warming is a real and serious threat and that humans are causing it, but they think climate impacts remain far enough in the future that they are a lower priority issue.^[19]

Plant-based diets are of interest in preventing and managing chronic diseases.^[21][22] TheBritish Dietetic Association stated that a plant-based diet "can support healthy living at every age and life stage", but as with any diet it should be properly planned.^[2] TheGovernment of Canada andHeart and Stroke Foundation of Canada issued 2024 guidelines for planning meals with plant-based protein sources, including menu ideas for substituting meats with plant foods.^[23][24]

Not all plant-based foods are equally healthy. Rather, plant-based diets including whole grains as the main form of carbohydrate, unsaturated fats as the main form of dietary fat, an abundance of fruit and vegetables, and adequate n-3 fatty acids can be considered healthy.^[25]

With processed plant-based foods, such as vegan burger patties or chicken-like nuggets, becoming more available, there is also concern that plant-based diets incorporating these foods may become less healthy.^[26]

In practice lacto-ovo vegetarians or vegans seem to have a higher overall diet quality compared with nonvegetarians. The reason for this is the closer adherence to health organisation recommendations on consumption of fruits, whole grains, seafood and plant protein and sodium. The higher diet quality in vegetarians and vegans may explain some of the positive health outcomes compared with nonvegetarians.^[27]

Plant-based foods are not a reliable source ofvitamin B₁₂ by default. A lack of B₁₂ is associated with a range of conditions and it is essential for human health.^[28] Those eating a fully plant-based diet should ensure adequate B₁₂ intake via supplementation or consumption of fortified foods,^[29] such as fortified plant milks or yogurts, nutritional yeast, or fortified cereals.^[30]

Even those eating a plant-based diet including a small amount of animal products are at an increased risk of a lower than recommended B₁₂ intake^[31] without supplementation or regular consumption of fortified foods.

Observational studies show that vegetarian diets are lower in energy intake than non-vegetarian diets^[32] and that, on average, vegetarians have a lowerbody mass index than non-vegetarians.^[33]

Two reviews of preliminary research found that vegetarian diets practiced over 18 weeks or longer reduced body weight in the range of 2–3 kilograms (4.4–6.6 lb),^[34][35] with vegan diets used for 12 weeks or longer reducing body weight by 4 kg.^[36]

In obese people, a 2022 review found that plant-based diets improved weight control,LDL andtotal cholesterol, blood pressure,insulin resistance, and fasting glucose.^[37]

Some reviews indicate that plant-based diets including fruits, vegetables, whole grains, legumes, and nuts are associated with a lower risk of diabetes.^[38][39][40]

Therefore, vegetarian and vegan diets are underclinical research to identify potential effects ontype 2 diabetes, with preliminary results showing improvements in body weight andbiomarkers ofmetabolic syndrome.^[41][42]

When the focus waswhole foods, an improvement ofdiabetesbiomarkers occurred, including reducedobesity.^[38][43][44] In diabetic people, plant-based diets were also associated with improved emotional and physical well-being, relief of depression, higherquality of life, and better general health.^[43]

The American College of Lifestyle Medicine stated that diet can achieve remission in many adults with type 2 diabetes when used as a primary intervention of whole, plant-based foods with minimal consumption of meat and other animal products. There remains a need for morerandomized controlled trials "to assess sustainable plant-based dietary interventions with whole or minimally processed foods, as a primary means of treating diabetes with the goal of remission."^[45]

Plant-based diets are associated with a decreased risk ofcolorectal andprostate cancer.^[46][47][48] Vegetarian diets are associated with a lower incidence from total cancer (-8%). A vegan diet seems to reduce risk of incidence from total cancer by -15%. However, there was no improvement in cancer mortality.^[49]

Preliminary studies indicate that a plant-based diet may improve the gutmicrobiome.^[50][51]

A 2022 review ofprospective cohort studies showed that vegetarian diets are associated with a 15% reduced risk ofcardiovascular diseases and 21% reduced risk incoronary artery disease, but with no effect on the risk ofstroke; for vegan diets, only a reduced risk in coronary artery disease was found.^[52]

Other reviews found that plant-based diets, including vegan and vegetarian diets, may lower the risk of cardiovascular diseases,^[4][7] includingblood pressure^[53][54] andblood lipid levels.^[55][56]Randomized clinical trials also showed that the reduction in blood pressure (about 4 mmHg) associated with a vegan dietwithout caloric restrictions is comparable to reductions observed with dietary practices recommended by medical societies and use of portion-controlled diets.^[57]

Preliminary evidence indicates that people on a long-term vegan diet show improvements in cardiovascular and metabolic risk factors.^[58]

The effect of plant-based diets on bone health is inconclusive. Preliminary research indicates that consuming a plant-based diet may be associated with lowerbone density, arisk factor for fractures.^[59][60][61]

Plant-based diets are under study for their potential to reduceinflammation.^[62]C-reactive protein – abiomarker for inflammation – may be reduced by consuming a plant-based diet,^[63] particularly in obese people.^[64]

A 2020 review stated that dietary patterns based on consuming vegetables, fruits, legumes, nuts, whole grains, unsaturated vegetable oils, fish, lean meat or poultry, and are low in processed meat, high-fat dairy and refined carbohydrates or sweets, are associated with a decreased risk ofall-cause mortality.^[65]

In a meta-analysis published online in 2023, plant-based diets were shown to have a moderate positive effect on aerobic performance and had no effect on strength performance.^[66]

There is scientific consensus that plant-based diets offer lowergreenhouse gas emissions, land use and biodiversity loss. In addition, dietary patterns that reduce diet-related mortality also promote environmental sustainability.^[68][69][70]

As a significant percentage of crops around the world are used to feed livestock rather than humans, eating less animal products helps tolimit climate change (such as throughlow-carbon diets) andbiodiversity loss.^[71] Especially beef, lamb and cheese have a very high carbon footprint.^[72] While soy cultivation is a "major driver of deforestation in theAmazon basin",^[73] the vast majority of soy crops are used for livestock consumption rather than human consumption.^[74] Adopting plant-based diets could also reduce the number of animals raised and killed for food onfactory farms.^[75]

Research from 2019 on six diets found the plant-based diets more environmentally friendly than the diets higher in animal-sourced foods. Of the six mutually-exclusive diets; individuals eatingvegan, vegetarian andpescetarian diets had lower dietary-carbon footprints than typicalomnivorous diets, while those who ate 'paleolithic' andketogenic diets had higher dietary-carbon emissions due to their animal sourced foods.^[76]

A 2020 study found that theclimate change mitigation effects ofshifting worldwidefood production andconsumption to plant-based diets, which are mainly composed of foods that require only a small fraction of the land and CO₂ emissions required formeat and dairy, could offset CO₂ emissions equal to those of past 9 to 16 years of fossil fuel emissions in nations that they grouped into 4 types. The researchers also provided a map of approximate regional opportunities.^[77][78]

It may be possible to increase the transition from meat eating to a plant based diet throughsocial contagion, by which behaviour, emotions, or conditions spread spontaneously through a group ornetwork. A Max Planck Institute study from 2020 found that when meat-eaters are accompanied by vegetarians and have a choice of eating dishes with or without meat, they're more likely to choose a vegetarian dish. This probability increases as the number of vegetarians accompanying the meat eaters increases.^[79] Once enough people have been influenced, the community can reach atipping point, in which a majority of people transition to a new habit; a 2018 study published in Nature claims that with only 25 per cent of a population, a minority perspective was able to overturn the majority.^[80]

According to a 2021Chatham House report, supported by theUnited Nations Environment Programme, a shift to "predominantly plant-based diets" will be needed to reducebiodiversity loss andhuman impact on the environment. The report said that livestock has the largest environmental impact, with some 80% of all global farmland used to rear cattle, sheep and other animals used by humans for food. Moving towards plant-based diets would free up the land to allow for the restoration of ecosystems and the flourishing of biodiversity.^[67]

A 2022 study published inNature Food found that if high-income nations switched to a plant-based diet, vast swaths of land used for animal agriculture could be allowed toreturn to their natural state, which in turn has the potential to pull 100 billion tons of CO₂ out of the atmosphere by the end of the century. Around 35% of all habitable land around the world is used to rear animals used by humans in food production.^[81][82]

A 2023 study published inNature Food found that avegan diet vastly decreases the impact on the environment from food production, such as reducing emissions, water pollution and land use by 75%, reducing the destruction ofwildlife by 66% and the usage of water by 54%.^[83] Another study published in the same year inNature Communications found that replacing half of the beef, chicken, dairy and pork products consumed by the global population withplant-based alternatives could reduce the amount of land used by agriculture by almost a third, bring deforestation to a near-halt, restore biodiversity, and reduce GHG emissions from agriculture by 31% by 2050. However, the report also notes that agrowing population and risingaffluence are projected to increase demand for animal products which could have negative impacts on the environment.^[84][85][86]

A reduction in meat consumption and a shift to more plant-based diets is needed to reach climate targets, addressing public health problems, and protecting animal welfare. Research has been done on how to best promote such a change inconsumer behaviour.^[87]

Some public health organisations advocate a plant-based diet due to its low ecological footprint. These include the Swedish Food Agency in its dietary guideline^[88] and a group ofLancet researchers who propose aplanetary health diet.^[89]Vegan climate activistGreta Thunberg also called for more plant-based food production and consumption worldwide.^[90] A 2022 report by theStockholm Environment Institute and theCouncil On Energy, Environment and Water included protectinganimal welfare and adopting plant based diets on a list of recommendations to help mitigate the ecological and social crises bringing the world to a "boiling point".^[91]Denmark and South Korea announcedplant-based action plans in 2023.^[92]Plant-based protein is gaining popularity as a sustainable and nutritious alternative to animal-based sources.^[93]

• List of diets
• Plant-based action plan
• Veganism
• Vegetarianism and religion
• Mediterranean diet

• Plant-based diets

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