Vegetarian Diet

Diet Reference Archive: a diet

Vegetarian Diet

A way of eating that leaves out meat, poultry and fish and usually keeps dairy foods, eggs or both. People choose it for health, ethical, environmental, religious and cultural reasons, and research links it with lower rates of heart disease, mostly from studies that follow people over many years.

Family: Plant-based and plant-forward diets Promoted by: religious and philosophical traditions, vegetarian societies, and, in planned form, the Academy of Nutrition and Dietetics and the American Heart Association First appeared: as a practice, in ancient religious and philosophical traditions; as an organized movement, with the first vegetarian society, in England in 1847 GRADE: Moderate for the association between vegetarian eating, with vegans included, and lower incidence of cardiovascular disease, compared with nonvegetarian eating, in generally healthy adults followed for 5 to 28 years in cohort studies; published umbrella review rating (Landry et al., 2024)

ON THIS PAGE

1. In brief
2. Overview
3. In practice
4. For the coach
5. The evidence (opens on request)
6. Mechanisms (opens on request)
7. Risks, contraindications and myths (opens on request)
8. Key terms
9. Review questions
10. References
11. Evidence rating and review record

The summary and sections 1 to 3 are the short version and are open when the page loads. Sections 4 to 6 hold the research detail, the biology, and the cautions. Each of those opens when you select its heading, and you can read the page without opening them. Back to the Diet Reference Archive index.

In brief

What is it? A vegetarian eats no meat, poultry or fish. Most vegetarians still eat dairy foods and eggs, and are called lacto-ovo vegetarians; some eat dairy foods but not eggs (lacto-vegetarians), and some eat eggs but not dairy foods (ovo-vegetarians). A diet with no animal foods at all is vegan, and the Vegan Diet page covers it.

Does it work? In studies that follow large groups of people for years, vegetarians, usually with vegans counted among them, have had lower rates of heart disease than people who eat meat, and a published review rates that evidence moderate in certainty. It is an association: vegetarians in these studies also smoked less and were more active, and the studies cannot show that the diet caused the difference. Trials, mostly a few months long and mostly in people with diabetes or heart risk, found modest drops in LDL cholesterol and in HbA1c, a long-term measure of blood sugar. For stroke, cancer and length of life the findings are mixed, and the searches for this page did not identify a trial in generally healthy people designed to test whether the diet prevents heart attacks or death.

Is it safe? For adults, a planned vegetarian diet can be nutritionally adequate, in the position of the Academy of Nutrition and Dietetics. The cautions that matter most are vitamin B12, which comes naturally only from animal foods, and iron and zinc, which are absorbed less well from plant foods. Several large British studies have also found more hip fractures in vegetarians than in regular meat eaters, partly explained by lower body weight.

Who should not do it without talking to a doctor or dietitian first? Anyone who is pregnant or breastfeeding, and parents planning a vegetarian diet for a baby, child or teenager. Older adults, especially anyone with low bone density, past fractures or trouble keeping up their strength. Anyone with a kidney condition, anyone taking medication for diabetes or blood pressure, anyone taking warfarin, and anyone with a history of disordered eating.

Related pages: Mediterranean Diet and DASH Diet; also the Vegan Diet, Pescatarian Diet, Flexitarian Diet and Whole-Food Plant-Based Diet pages. Full list on the archive index.

1. Overview

What you eat

A vegetarian diet keeps every kind of food except the flesh of animals. Its base is vegetables, fruits, whole grains, beans, lentils, soy foods such as tofu, nuts and seeds, and, for most vegetarians, dairy foods and eggs. The Academy of Nutrition and Dietetics defines vegetarian dietary patterns as those that exclude meat, poultry and seafood, and the American Heart Association groups three named types under one heading (Gardner et al., 2023; Raj et al., 2026):

• Lacto-ovo vegetarian: dairy foods and eggs are eaten. Researchers describe it as the most common type of vegetarian diet (Sofi et al., 2018).
• Lacto-vegetarian: dairy foods are eaten, eggs are not.
• Ovo-vegetarian: eggs are eaten, dairy foods are not.

None of the three sets amounts or proportions. A vegetarian plate can be built mostly from whole foods, or mostly from refined grains, sweets and processed meat substitutes, and the health research reflects whichever version people eat. The American Heart Association counts lacto-ovo vegetarian eating among the patterns that align best with its dietary guidance when it is followed as intended, and adds that such diets are “not inherently health promoting” when they are made up mainly of refined grains, sweets and other less healthy plant foods (Gardner et al., 2023).

What you avoid or limit

The rule is to leave out meat, poultry, fish and seafood, and it is usually a firm rule rather than a guideline. Lacto-vegetarians also leave out eggs, and ovo-vegetarians leave out dairy foods. Some vegetarians also check labels for ingredients made from animals; how strictly varies from person to person, and the sources opened for this page do not set a single rule. Some traditions add limits of their own for religious reasons: in a national survey in India, about two-thirds of Jains said they abstain from root vegetables such as garlic and onions (Corichi, 2021).

How research defines a vegetarian

Studies do not all mean the same thing by “vegetarian,” and the differences matter when reading section 4. In the British EPIC-Oxford study, participants answered yes or no to 4 questions about eating meat, fish, dairy foods and eggs, and anyone who ate no meat or fish but ate dairy foods or eggs was counted as a vegetarian (Tong et al., 2019). In the Adventist Health Study 2 in North America, diet groups came from a food questionnaire. In a 2009 analysis of that cohort, a lacto-ovo vegetarian ate dairy foods or eggs at least once a month and red meat, poultry or fish less than once a month, so a person who ate meat occasionally could still be counted (Tonstad et al., 2009).

Some analyses also fold other groups in. The Adventist study’s combined “vegetarian” group included pesco-vegetarians, who eat fish, and semi-vegetarians, who eat red meat or poultry at least once a month but less than once a week, and several large British analyses count vegans among vegetarians because vegans are too few to study alone (Appleby et al., 2016; Orlich et al., 2013; Tong et al., 2019; Tonstad et al., 2009). People’s own label can also differ from what they eat: in a national United States food survey from the 1990s, the authors concluded that “self-defined vegetarians may consume red meat, poultry, or fish” (Haddad & Tanzman, 2003). Wherever a study allows it, this page reports the result for vegetarians who eat dairy foods or eggs, and it says plainly when vegans, fish eaters or occasional meat eaters were counted in.

Where it came from

Avoiding meat is far older than the modern word for it. A historical review notes that early human food cultures were plant-based, that Hinduism and Buddhism have recommended a vegetarian way of life since their beginnings, and that the Greek philosopher Pythagoras is considered the father of ethical vegetarianism. In Europe, the first vegetarian society was started in England in 1847, the International Vegetarian Union was founded in 1908 (International Vegetarian Union, n.d.; the review calls it the International Vegetarian Society), and the first vegan society began in 1944. The same review describes a shift around the turn of the 21st century, as the older worry that vegetarians would be malnourished gave way to research reporting health benefits (Leitzmann, 2014).

In the United States, 4 percent of adults in a 2023 Gallup poll said they were vegetarian and 1 percent vegan, similar to readings in 2012 and 2018 and slightly below the 6 percent recorded in 1999 and 2001. Women (6 percent) were more likely than men (2 percent) to say they ate a vegetarian diet (Jones, 2023). In India, 39 percent of adults in a 2021 Pew Research Center survey described themselves as vegetarian, with the definition left to each respondent (Corichi, 2021).

Cultural and philosophical context

Vegetarian eating belongs to several religious and philosophical traditions, and a client may bring it as part of who they are rather than as a diet chosen for health. In the Pew survey in India, 92 percent of Jains, 44 percent of Hindus, 10 percent of Christians and 8 percent of Muslims described themselves as vegetarian, many Indians who are not vegetarian still limit meat in some way, and many said that following their religion’s food rules is part of what makes a person a member of it (Corichi, 2021). In North America, the Seventh-day Adventist church promotes vegetarianism, which is one reason Adventists have been studied so closely (Tonstad et al., 2013).

Other reasons people give are concern for how animals are treated, the environment, health, cost, and cultural or religious dietary guidance (Raj et al., 2026). This page describes these as reasons people hold, in their own terms. It rates only the health claims made for the diet.

What it claims to do

The diet is promoted on several grounds at once: health, animal welfare, the environment and faith. On health, the most authoritative claim comes from the Academy of Nutrition and Dietetics, whose 2025 position is that “in adults, appropriately planned vegetarian and vegan dietary patterns can be nutritionally adequate and can offer long-term health benefits such as improving several health outcomes associated with cardiometabolic diseases” (Raj et al., 2026). Its earlier 2016 position said such diets are “appropriate for all stages of the life cycle,” including pregnancy, infancy and childhood (Melina et al., 2016); the 2025 paper covers only adults who are not pregnant or breastfeeding and leaves those stages to specific guidance. The American Heart Association lists healthy versions of ovo/lacto vegetarian eating among the patterns that “can support cardiovascular health” (Lichtenstein et al., 2026). Section 4 takes each health claim in turn.

What it gets right

Planned well, a vegetarian diet already has much of what heart-health guidance asks for: vegetables, fruits, whole grains, legumes and nuts at the center, and no processed meat. The American Heart Association places lacto-ovo vegetarian eating in its top tier of alignment with its guidance, alongside Mediterranean, DASH-style and pescatarian eating, when each is followed as intended (Gardner et al., 2023). For a client who eats this way for ethical or religious reasons, that overlap is something a coach can honor without weighing in on the reasons themselves. What the diet does not do on its own is guarantee a healthy plate, because leaving out meat says nothing about what replaces it.

How clients describe it, and what it gets confused with

Clients say “I’m vegetarian,” “I don’t eat meat,” “I’m mostly vegetarian,” “I went plant-based,” “we do meatless Mondays,” or “I eat fish but not meat.” These can mean quite different diets, so it helps to ask. Someone who eats fish but no meat is following a pescatarian pattern, covered on the Pescatarian Diet page. Someone who eats meat, poultry or fish now and then is closer to the Flexitarian Diet page. Someone who eats no animal foods at all is vegan, covered on the Vegan Diet page. The boundary with this page is the same each time: a vegetarian eats no meat, poultry or fish, even occasionally.

“Plant-based” has no standard definition (Raj et al., 2026). The Whole-Food Plant-Based Diet page covers the version defined by food quality, along with the research on plant-based diet indexes that score how healthful a plant-based diet is. A client from a religious tradition may also follow rules that go beyond meat, such as avoiding eggs or certain vegetables, and the single word “vegetarian” may not capture them.

2. In practice

A typical day of eating

For a lacto-ovo vegetarian: breakfast is oatmeal made with milk, topped with berries and walnuts, or eggs on whole-grain toast. Lunch is lentil soup with a cheese and vegetable sandwich, or a bowl of black beans, brown rice, salsa and avocado. A snack is fruit with yogurt, a handful of nuts, or hummus with raw vegetables. Dinner is a tofu and vegetable stir-fry over brown rice, a chickpea curry with whole-wheat flatbread, or whole-grain pasta with white beans and greens. A lacto-vegetarian version swaps the eggs for yogurt or beans, and an ovo-vegetarian version uses a fortified soy drink in place of milk. What makes the day work is a protein food at most meals, and a plan for the nutrients covered in section 6.

Cost, products, and who profits

Whether a vegetarian diet costs more depends on what it replaces and where a person lives. A global modeling study priced nutritionally balanced versions of several healthy diets using 2017 food prices from 150 countries. In high-income and upper-middle-income countries, vegetarian and vegan versions built around legumes and whole grains cost 22 to 34 percent less than current diets, and versions heavier in fruits and vegetables 17 to 27 percent less; in lower-middle-income and low-income countries, all the healthy patterns cost more than current diets, by 18 to 45 percent (Springmann et al., 2021). These are modeled diets priced from national data, not what households bought.

The diet does not depend on any branded product: beans, lentils, grains, eggs, milk and vegetables are ordinary staples. It has nonetheless become a large market. The Academy’s position paper cites a forecast that the global plant-based food market will grow from 11.3 billion dollars in 2023 to 35.9 billion dollars in 2033, and notes that while some meat and milk alternatives can be healthful, other convenience products may be high in sodium, saturated fat, additives and preservatives (Raj et al., 2026). The American Heart Association urges some caution with plant-based meat alternatives because many are ultraprocessed (Lichtenstein et al., 2026). The companies that make these products and vitamin supplements profit when a client goes vegetarian. A vegetarian diet does not require branded meat substitutes. Fortified foods or supplements may still be needed; a dietitian or clinician can help determine that.

Environmental footprint

The most detailed comparison of the diets vegetarians eat comes from a British study that linked the diets reported by 55,504 EPIC-Oxford participants to environmental data on foods sold in the United Kingdom in 2019. Standardized to 2,000 calories a day, the diets of 15,751 vegetarians produced an estimated 4.16 kilograms of greenhouse gas emissions a day, in carbon dioxide equivalents, against 10.24 kilograms for people eating at least 100 grams of meat a day and 5.37 kilograms for people eating less than 50 grams. The vegetarian diets used about 6.0 square meters of farmland a day against 16.8 for the high meat eaters, and about 0.53 cubic meters of water against 0.89 (Scarborough et al., 2023).

These are diets people reported, paired with modeled footprints. The diets were reported in the 1990s, before most of the meat and milk alternatives now on sale, and the footprints are averages across production methods and countries of origin, which the authors carried as uncertainty in their estimates. Vegetarians in the study ate more cheese than any meat-eating group, and the study found that environmental impact rose with the amount of animal foods eaten, so the footprint of any one vegetarian diet depends on which foods it relies on (Scarborough et al., 2023).

Cultural fit

The diet fits easily with food traditions that already center on legumes, grains and vegetables, and with the religious traditions that teach or encourage it. It asks more of traditions in which meat or fish sits at the center of shared meals, holidays and hospitality. The American Heart Association notes that its top-tier patterns, lacto-ovo vegetarian among them, can be adapted to respect cultural practices, food preferences and budget (Gardner et al., 2023), and the Academy’s position paper asks dietitians to help clients return to familiar, culturally appropriate plant foods (Raj et al., 2026). Eating with others can be a point of friction too: in the Pew survey in India, vegetarian Jains were the least likely to say they would ever eat in a restaurant that also serves meat or in the home of a friend who is not vegetarian (Corichi, 2021).

What makes people stop

Most people in the large cohorts who called themselves vegetarian kept to it: in resurveys 4 to 14 years after joining, 68 to 89 percent of vegetarians in the British cohorts and one Indian cohort were still classified as vegetarian, and 12 percent or fewer had returned to eating meat (Dunneram et al., 2026). In a Taiwanese Buddhist cohort, 124 of the 1,177 people who were vegetarian at the start had returned to eating meat by a later follow-up (Chiu et al., 2018).

Evidence about why people stop is limited. In a convenience sample of 247 current and former pescatarians, vegetarians and vegans, recruited mainly online, current limiters were more likely than the 51 former limiters to have changed gradually rather than abruptly, to have joined a vegetarian or vegan group, and to describe the diet as part of their identity (Haverstock & Forgays, 2012). In a United States survey of 1,313 current and former vegetarians and vegans analyzed together, political conservatism was associated with having stopped the diet. Differences in justice-related motivations and perceived social support helped account for that association; meat cravings and inconvenience explained little of that particular relationship (Hodson & Earle, 2018). Both samples combined several dietary patterns, so neither establishes how common these reasons are among vegetarians generally or how many people stop, and neither shows why any one person stopped.

What happens when you stop

Few studies have followed people after a vegetarian diet ends. The longest trial identified for this page compared a lacto-ovo vegetarian diet with a standard weight-loss diet, both reduced in calories and fat, over a 12-month program and a 6-month maintenance phase; at 18 months, no clear difference in weight loss was detected between the two diets (Burke et al., 2008). The searches for this page did not identify a trial that measured what happens to cholesterol, blood sugar or blood pressure after people stop a vegetarian diet.

Changing diet groups also matters for how the cohort studies are read. In the British analysis of deaths, the hazard ratio for death from any cause in the combined vegetarian and vegan group, compared with regular meat eaters, changed from 1.02 to 0.92 (95% confidence interval, 0.84 to 0.99) when people known to have changed diet group during follow-up were excluded (Appleby et al., 2016). That is a reminder that a person’s diet at the start of a study is not always the diet they kept.

Common variations

• Lacto-ovo, lacto- and ovo-vegetarian: the three named types, which differ in whether dairy foods and eggs are eaten (Gardner et al., 2023).
• Very low-fat vegetarian programs: the program associated with Dean Ornish, used in trials in people with heart disease, is a lacto-ovo vegetarian diet with less than 10 percent of energy from fat that allows no animal protein except nonfat dairy foods and egg whites (Wang et al., 2023). This program is commonly called the Ornish diet.
• Religious and traditional forms: Jain vegetarianism, which often excludes root vegetables (Corichi, 2021), and Buddhist practice in Taiwan, where some people eat vegetarian only at breakfast or on the 1st and 15th days of each lunar month rather than full time (Chiu et al., 2018).
• Diets that are often called vegetarian but are not, by this page’s definition: pesco-vegetarian or pescatarian eating, which includes fish, and semi-vegetarian or flexitarian eating, which includes some meat. The Pescatarian Diet and Flexitarian Diet pages cover them.

3. For the coach

SCOPE OF PRACTICE

A health and wellness coach does not prescribe, adjust, endorse or discourage a vegetarian diet, and does not diagnose or treat. The coach helps the client understand what they have chosen, notice how it is going, and decide what to do next.

For most adults, vegetarian eating is a personal choice that needs no clinician to begin. The points at which it needs a registered dietitian or a physician are specific: pregnancy and breastfeeding; feeding a baby, child or teenager; older age with low bone density, past fractures or loss of strength; a kidney condition; diabetes treated with insulin or another medicine that can cause low blood sugar; blood pressure medication; warfarin; and any question about supplements such as vitamin B12, iron or vitamin D, where the Academy of Nutrition and Dietetics says individual assessment of intake, clinical status and laboratory measures comes before a specific recommendation (Raj et al., 2026).

Who does what

The physician

Orders and reads the tests that matter for this diet, such as a blood count, vitamin B12 status, iron stores and vitamin D when indicated; assesses bone health in an older adult or after a fracture; and adjusts any medication whose dose depends on diet. In one trial in people with type 2 diabetes, a study physician reduced diabetes medication for 43 percent of participants on a vegetarian diet because of repeated low blood sugar (Kahleova et al., 2011).

The registered dietitian

Plans the diet around the person: protein at meals, sources of iron and zinc and ways to absorb them, calcium and vitamin D from food or fortified products, iodine, omega-3 fats, and whether vitamin B12 from a supplement or fortified foods is needed. The Academy names vitamin B12, iodine, iron, choline and vitamin D as the micronutrients of concern for vegetarians and describes the dietitian’s role as tailoring the pattern to the client’s health, values, culture and life (Raj et al., 2026).

The health and wellness coach

Helps the client see their own reasons for eating this way, whether health, animals, the planet, faith, family or cost, and build the practical life around the choice: shopping and cooking skills, eating out, family meals, travel, and a short list of go-to meals the client enjoys. With the client’s permission, the coach can share general guidance from recognized authorities, such as the Academy’s statement that vitamin B12 needs planning, and explore what the client wants to do with it. The coach notices when the diet seems to be narrowing rather than widening what a client eats, and holds the referral line for nutrient, medication and life-stage questions.

What a client bringing this diet needs

Clients arrive at vegetarian eating from very different places. A client who has been vegetarian all their life, by faith or family tradition, is not asking whether to stay vegetarian; they may want help with a health goal within the way they already eat, and the first need is respect for that. A client newly vegetarian for ethical or environmental reasons often needs practical skills: what to cook, what to order, how to handle family meals. A client trying it for health or weight may be hoping it will fix more than any diet can. A teenager or young adult who has recently gone vegetarian may be doing so for ordinary reasons, or may be using it to restrict eating, and the coach listens for which.

What the coaching conversation can offer that a search engine cannot is clarity about the client’s own reasons, a realistic look at how the diet fits their week, their family and their budget, and a plan the client owns. It also offers a calm place to notice whether the diet is working for them, including the nutrients that need planning, without the coach becoming the planner.

What to ask

• What drew you to eating this way, and what matters most to you about it?
• What does a usual day of eating look like for you now, and what would you like to be different?
• Who else is part of your food decisions, such as family, a doctor or a dietitian, and what have they said?

Referral red flags

A client who is pregnant, trying to become pregnant or breastfeeding, or who is planning a vegetarian diet for a baby, child or teenager, needs a dietitian and their own clinician involved. A client who describes ongoing tiredness, an inflamed tongue, palpitations or neurological changes is describing symptoms that the Office of Dietary Supplements lists for vitamin B12 deficiency, which can take years to appear, and weakness, fatigue and difficulty concentrating can also come with iron deficiency anemia (National Institutes of Health Office of Dietary Supplements, 2025a, 2025b). The coach does not suggest a cause; the client takes the symptoms to a clinician, who works out what is going on.

A client taking insulin, a sulfonylurea, blood pressure medication or warfarin who plans a substantial change in eating keeps the prescriber informed before making it. A possible low blood sugar episode is treated first under the client’s own diabetes plan; severe symptoms, or an episode the client cannot manage, call for emergency help; and the client then tells the prescriber about it. An older client with past fractures or low bone density, and any client losing weight without meaning to, are reasons to involve a clinician. A client with kidney disease needs the kidney care team in the plan.

A client whose vegetarian diet comes with a growing list of other food rules, fear of eating, or distress about weight is worth asking about directly: what each restriction is for, whether it causes distress, whether it is narrowing what they eat, and whether it is getting in the way of daily life. Most people choose vegetarian eating for ordinary reasons such as ethics, faith or family. Where the answers raise a real concern about disordered eating, the coach follows their own referral process, or tells the client’s clinician under an existing care plan.

Special populations

Pregnancy and breastfeeding

The Academy’s 2025 position paper does not cover pregnancy or breastfeeding, calling guidance for these stages outside its scope; its 2016 position had described planned vegetarian diets as appropriate for them (Melina et al., 2016; Raj et al., 2026).

A 2019 review included 38 observational studies, 19 in meta-analyses and 19 in its narrative synthesis. Its pooled low-birth-weight analysis found no statistically clear overall association with a vegetarian diet in pregnancy, an odds ratio of 1.27, from 0.98 to 1.65. In the subgroup of 7 studies of Asian mothers, vegetarian diets were associated with higher odds of a low-birth-weight baby, 1.33, from 1.01 to 1.76. No clear difference in average birth weight was detected in the 5 studies that reported it. The studies used differing dietary definitions and could not adequately separate diet from other maternal and social factors (Tan et al., 2019). The searches for this page did not identify a trial of a vegetarian diet during pregnancy or breastfeeding. Diet changes in either stage belong with the obstetric clinician and a dietitian.

Children and adolescents

A meta-analysis of 59 cross-sectional studies included 7,280 lacto-ovo vegetarian children and adolescents, compared with omnivores; the same studies also included 1,289 vegan children. The lacto-ovo vegetarian children ate less energy, protein, vitamin B12, vitamin D and zinc and more fiber, iron and folate; were on average shorter and leaner, with less fat mass and bone mineral; and had lower ferritin and vitamin D levels and higher odds of iron deficiency and anemia, although most group averages stayed within pediatric reference ranges. Every included study measured diet and health at one point in time, and families who choose the diet may differ in other ways, so the review cannot show that the diet caused these differences (Lotti et al., 2026). A Canadian cohort of 8,907 young children, among them 248 vegetarian children, including 25 vegans, found no clear differences in growth, ferritin, vitamin D or blood lipids but higher odds of underweight among the vegetarian children (Elliott et al., 2022), and a 2025 review of studies in high-income countries, nearly all cross-sectional, found no clear differences in height or body mass index in its pooled analyses (Reis et al., 2025). A child’s diet belongs with the family, the pediatrician and a dietitian.

Older adults

Two concerns stand out. Bone: in 3 British cohorts, vegetarians had higher rates of hip fracture than regular meat eaters, with hazard ratios of 1.25, 1.33 and 1.50; in the largest, about 3 more hip fractures per 1,000 people over 10 years, and lower body mass index explained about 28 percent of the difference (Tong et al., 2020; Webster et al., 2022, 2023). Muscle: in a 12-week trial in 108 adults aged 55 and older doing resistance training, those counseled toward a lacto-ovo vegetarian diet ate less protein, 1.24 against 1.58 grams per kilogram of body weight a day, and gained muscle mass, but the trial could not show that the vegetarian diet was not inferior for muscle gain (van Oppenraaij et al., 2026); this page read only the abstract. In a Chinese cohort of adults aged 65 and older, ovo-lacto vegetarians had a higher rate of frailty than omnivores (Y. Huang et al., 2025). The Academy describes a protein intake of at least 1 gram per kilogram a day for older adults (Raj et al., 2026); the individual plan belongs with a dietitian.

Athletes and people with high activity

The Academy’s position paper concludes that plant proteins can support muscle building in active adults, and that for active adults and athletes seeking gains in muscle size or strength there does not appear to be a disadvantage when plant protein reaches at least 1.5 grams per kilogram a day (Raj et al., 2026). In a cross-sectional study of 76 recreational runners, no clear difference in maximum power output in an exercise test was detected among lacto-ovo vegetarians, vegans and omnivores (Nebl et al., 2019); a study of this design cannot show that the diet caused the result. Small trials have tested vegetarian variants and exercise performance, but do not establish an advantage or disadvantage for a usual vegetarian diet or competitive athletes. In one, 9 recreationally active men ate their usual diet and, in random order, a 4-day low-protein vegetarian diet without meat, cheese or eggs; time to exhaustion in a cycling test did not differ clearly, oxygen use during cycling below maximum effort was higher after the vegetarian diet, and that diet supplied less energy and about half the protein (Hietavala et al., 2012). Iron needs are higher for vegetarians in general (National Institutes of Health Office of Dietary Supplements, 2025a), and a sports dietitian is the right referral for an athlete’s plan.

People taking medication for diabetes, blood pressure, or blood thinning

Vegetarian eating can change medication needs. In a 24-week trial in people with type 2 diabetes taking oral medicines, a study physician reduced diabetes medication because of repeated low blood sugar in 43 percent of those on a calorie-reduced vegetarian diet and 5 percent of those on a conventional diabetic diet (Kahleova et al., 2011); a later review describes the reductions as following high blood sugar, but the trial report says low blood sugar (Guest et al., 2024). Green leafy vegetables are the main dietary source of vitamin K, and people taking warfarin need a consistent vitamin K intake, because sudden changes can raise or lower the drug’s effect (National Institutes of Health Office of Dietary Supplements, 2021). The standing rule applies to diabetes medicine, blood pressure medication and warfarin alike: the client keeps the prescriber informed before a substantial change in eating, rather than asking permission for every food choice.

People with a history of disordered eating

A review of 20 studies in adolescents and young adults, most rated low in quality, found that most reported an association between vegetarian eating and eating disorders, that in many people the vegetarian diet was adopted after the disorder began, and that a vegetarian diet can serve as a socially acceptable way to avoid food; the authors called for prospective studies (Sergentanis et al., 2020). A 2026 review of 24 cross-sectional studies with 25,223 participants, which pooled eating-disorder symptom scores rather than diagnoses, found no clear difference between people following vegetarian or vegan diets and omnivores, with substantial variation among studies; this page read only its abstract (Díaz-Goñi et al., 2026). Both reviews rely largely on cross-sectional evidence, so neither establishes that vegetarian eating causes an eating disorder. Vegetarian eating does not mean a person has an eating disorder. The coach asks the questions under referral red flags above, and a real concern goes through the coach’s own referral process or to the client’s clinician.

People with kidney disease

A 2023 review of 4 small randomized trials in people with chronic kidney disease found mixed results on kidney filtration, with the 2 largest trials reporting improvement and 2 trials at high risk of bias finding no clear difference (Świątek et al., 2023). Individual needs depend on the stage of kidney disease, laboratory results and dialysis, and the kidney care team belongs in the plan.

Client misconceptions

Three come up most. The first is that a vegetarian diet is healthy by definition. It depends on what replaces the meat, and the American Heart Association says lacto-ovo vegetarian diets are not inherently health promoting when built mainly on refined grains and sweets (Gardner et al., 2023). The second is that vegetarians cannot get enough protein; for most adults eating a varied diet with enough food, the Academy finds that plant proteins together supply what the body needs, with older adults the main group to watch (Raj et al., 2026). The third is that research has proven vegetarians live longer. The large studies differ by population and by age, and none can rule out that vegetarians differ in other ways. Section 6 takes up each one.

🤝 COACHING CONNECTION

Daniel has type 2 diabetes and takes a sulfonylurea. His daughter went vegetarian, and he tells the coach he has decided to stop eating meat too, starting right away. The coach asks what draws him to it and what he pictures eating. Daniel says he wants to support his daughter and thinks it might help his blood sugar, and that he has not told his doctor because it is just food.

The coach asks whether he would like to hear a general point that people taking diabetes medicine often find useful, and Daniel says yes. The coach shares that big changes in eating can change how diabetes medicine works, which is why prescribers like to know about them beforehand, and asks what he makes of that. Daniel decides to message his doctor before he starts and to ask about seeing a dietitian. He and the coach list 3 vegetarian dinners the family already likes. The coach did not recommend the diet or advise against it.

4. The evidence

(select the heading to open or close this section)

Most of what is known about vegetarian diets comes from cohort studies that follow vegetarians and meat eaters for many years. In those studies vegetarians, usually with vegans counted in, have had lower rates of heart disease, and a published review rates that association moderate in certainty; for stroke, death and cancer the results are mixed or differ by cancer site. Trials are short, mostly 3 to 12 months, and show modest improvements in LDL cholesterol and blood sugar, mostly in people with diabetes or heart risk and often with vegan diets in the mix. The searches for this page did not identify a trial in generally healthy people designed to measure heart attacks, cancer or death.

Reading this section. Where a study reports vegetarians who eat dairy foods or eggs on their own, this page gives that result, and it labels any result that combines them with vegans, fish eaters or occasional meat eaters. Results for vegans alone are on the Vegan Diet page, for fish eaters on the Pescatarian Diet page, and for occasional meat eaters on the Flexitarian Diet page.

Evidence from randomized controlled trials

A trial assigns people to the diet by chance and compares them with people assigned to something else, which is the strongest way to test whether the diet itself causes a result. Trials of vegetarian diets are numerous but small and short. Most enrolled people who already had diabetes, high cholesterol, overweight or heart disease, and many tested vegan rather than lacto-ovo diets. Participants in diet trials know which diet they are eating, and none of the trials in one large review blinded participants (Koch et al., 2023). Pooled “vegetarian” results from trials therefore usually mix vegan and lacto-ovo diets, and the paragraphs below say how.

Cardiometabolic outcomes

A 2023 review combined 20 randomized trials with 1,878 adults who had, or were at high risk of, cardiovascular disease, with diets lasting about 6 months on average. Compared with all the comparison diets, vegetarian diets lowered LDL cholesterol by 6.6 mg/dL, from 3.1 to 10.1 lower, and HbA1c by 0.24 percentage points, from 0.07 to 0.40 lower, and the authors rated both results moderate in certainty using GRADE. Systolic blood pressure did not differ clearly, 0.1 mmHg lower, from 2.8 lower to 2.6 higher, rated low (Wang et al., 2023).

The trials in that review mixed vegan, lacto-ovo and lacto-vegetarian diets, and the authors rated most of them at high risk of bias. In the 5 trials of lacto-ovo vegetarian diets, LDL cholesterol fell by 14.1 mg/dL, from 3.6 to 24.5 lower, but 4 of those 5 also cut calories (Wang et al., 2023). The paper’s key points give the LDL cholesterol and HbA1c results as 6.8 mg/dL and 0.25 points; this page uses the figures in its results section.

A 2023 review of 30 trials comparing vegetarian or vegan diets with omnivorous diets, 15 of them vegetarian (12 lacto-ovo and 3 lacto-vegetarian), found lower total cholesterol, by 0.34 mmol/L, from 0.23 to 0.44 lower, lower LDL cholesterol, by 0.30 mmol/L, from 0.19 to 0.40 lower, and lower apolipoprotein B, the main protein in LDL particles. Triglycerides did not differ clearly, and the effect did not differ clearly between vegetarian and vegan trials. None of the trials blinded participants to their diet, and most lasted less than a year (Koch et al., 2023).

For adults with type 2 diabetes, a 2024 review by the Academy of Nutrition and Dietetics pooled 5 trials and found that vegetarian diets lowered HbA1c by 0.40 percentage points, from 0.21 to 0.59 lower, compared with nonvegetarian diets, an effect it rated moderate in certainty. Four of the 5 trials tested vegan diets. The 1 trial the review labels lacto-ovo vegetarian showed, on its own, a reduction of 0.44 points with an interval that did not exclude no effect, from 0.92 lower to 0.04 higher. Fasting blood sugar and LDL cholesterol did not differ clearly, both rated low in certainty, and the evidence on diabetes medication was mixed. A separate trial in the same review compared a vegan with a lacto-ovo vegetarian diet for 12 weeks and found no clear difference in HbA1c between them (Guest et al., 2024).

That lacto-ovo trial, in the Czech Republic, gave 74 people with type 2 diabetes either a vegetarian diet or a conventional diabetic diet, both reduced by 500 calories a day, with all meals provided, for 24 weeks; exercise was added to both groups for the second 12 weeks. The vegetarian diet allowed at most one serving of low-fat yogurt a day as its only animal food, so it was close to vegan. Insulin sensitivity rose more on the vegetarian diet, and 84 percent of each group completed the 24 weeks (Kahleova et al., 2011).

For blood pressure, a 2020 review of 15 trials with 856 participants found systolic pressure 2.66 mmHg lower on vegetarian diets, from 1.55 to 3.76 lower; in the lacto-ovo vegetarian trials alone, the difference, 1.75 mmHg lower, from 5.38 lower to 1.88 higher, did not exclude no effect (Lee et al., 2020). The paper reports a P value of 0.05 for the lacto-ovo comparison although its interval crosses zero; this page reports the interval. In people who already had cardiovascular disease, the Academy’s position paper reports that trials did not show a clear difference between vegetarian, including vegan, diets and other therapeutic diets in blood pressure, blood lipids, quality of life, cardiovascular events or death, with the evidence rated low or very low in quality (Raj et al., 2026).

Cancer

The searches for this page did not identify a randomized trial of a vegetarian diet that measured cancer. The evidence on cancer is observational and appears under the cohort studies below.

Body weight, as measured

This archive reports body weight as something a study measured, in that study’s own numbers, and not as a goal or a measure of whether an eating pattern worked; see the standing rule in the review record at the foot of this page. The one exception is weight a person loses without meaning to, which can signal a health problem and is a reason to involve a clinician, never a sign that a diet worked.

A 2016 review of 12 trials with 1,151 participants, over a median of 18 weeks, found that people assigned vegetarian diets lost 2.02 kilograms more than those on nonvegetarian diets, from 1.23 to 2.80 kilograms more. For lacto-ovo vegetarian diets alone, the difference, 1.48 kilograms, from 3.43 more to 0.47 less, did not exclude no difference, and in trials lasting a year or longer the overall difference was 1.13 kilograms (R.-Y. Huang et al., 2016). In an 18-month trial of 176 adults described as overweight, no clear difference in weight loss was detected between a lacto-ovo vegetarian diet and a standard diet, both reduced in calories and fat; 132 participants, 75 percent, completed the program (Burke et al., 2008).

In the CARDIVEG crossover trial described under head to head below, body weight fell by 1.88 kilograms on a calorie-reduced lacto-ovo vegetarian diet and 1.77 kilograms on a calorie-reduced Mediterranean diet over 3 months, with no clear difference detected between them (Sofi et al., 2018).

Mortality

The searches for this page did not identify a randomized trial in generally healthy people that measured death. In people with existing cardiovascular disease, the Academy’s position paper reports no clear difference in mortality in the trials it examined, with low or very low quality evidence (Raj et al., 2026).

Eating behavior and wellbeing

Two diabetes trials in the Academy’s review measured quality of life, with mixed results that the review rated very low in certainty: one, the trial described above, found a greater improvement on the vegetarian diet, and a vegan trial found no clear difference between groups (Guest et al., 2024). The observational findings on mood and on eating disorders are described below and in section 3.

Evidence from long-term prospective cohort studies

A cohort study follows people who already eat a certain way and records what happens to them. It can show that a pattern goes with an outcome; it cannot by itself show that the pattern caused it. The vegetarian cohorts are concentrated in a few groups: Seventh-day Adventists in North America, health-conscious volunteers in Britain, and Buddhist volunteers in Taiwan. Vegetarians in these studies generally smoked less and had other healthier habits than meat eaters, and although the analyses adjust for such differences, they cannot remove them entirely (Dunneram et al., 2026).

Cardiometabolic outcomes

A 2023 meta-analysis of prospective cohorts found that vegetarians, with vegans included, had a lower relative risk of cardiovascular disease than nonvegetarians, 0.85, from 0.79 to 0.92, across 8 cohorts with 621,282 people followed for 5 to 28 years, and a lower risk of coronary heart disease, 0.79, from 0.71 to 0.88. Total stroke did not differ clearly, 0.90, from 0.77 to 1.05, across 12 cohorts. Where a cohort reported only deaths, the review used deaths in place of new cases (Dybvik et al., 2023; Landry et al., 2024). An umbrella review by the Academy of Nutrition and Dietetics, which reviews existing reviews, rated the cardiovascular disease and coronary heart disease associations moderate in certainty using GRADE, and the stroke association low (Landry et al., 2024).

One detail of that pooled estimate matters for this page. For the Adventist Health Study 2, the meta-analysis used the study’s combined “vegetarian” result, which counted pesco-vegetarians and semi-vegetarians along with lacto-ovo vegetarians and vegans (Appleby et al., 2016; Dybvik et al., 2023; Orlich et al., 2013). In the published full report, lacto-ovo vegetarians had a hazard ratio for cardiovascular death of 0.90, from 0.76 to 1.06, compared with nonvegetarians, so no statistically clear difference was detected (Orlich et al., 2013). This measures cardiovascular deaths, not new cardiovascular disease.

The largest single British study, EPIC-Oxford, followed 48,188 people for 18.1 years. Vegetarians, with vegans included, had a lower rate of ischemic heart disease than meat eaters, a hazard ratio of 0.78, from 0.70 to 0.87, equal to about 10 fewer cases per 1,000 people over 10 years. When the analysis also adjusted for self-reported high blood pressure, high cholesterol, diabetes and body mass index, the hazard ratio was 0.90, from 0.81 to 1.00, suggesting that those factors explain part of the difference. The same vegetarians had a higher rate of stroke, 1.20, from 1.02 to 1.40, about 3 more cases per 1,000 people over 10 years, mostly from hemorrhagic stroke, the kind caused by bleeding, 1.43, from 1.08 to 1.90 (Tong et al., 2019).

Analyzed apart from vegans, the study’s 14,422 vegetarians had hazard ratios of 0.77, from 0.69 to 0.86, for ischemic heart disease, 1.17, from 1.00 to 1.38, for total stroke, and 1.48, from 1.11 to 1.97, for hemorrhagic stroke, close to the combined results. The estimates of cases per 1,000 people come from the combined vegetarian and vegan analysis and do not apply to this group on its own (Tong et al., 2019).

Results from Taiwan point the other way on stroke. In 2 cohorts of Taiwanese Buddhist volunteers, vegetarians had lower rates of ischemic stroke in both, and lower overall stroke, 0.52, from 0.33 to 0.82, in the larger one, which recorded 121 strokes over about 77,000 person-years; the vegetarians also had lower vitamin B12 and higher homocysteine levels in their blood (Chiu et al., 2020). The populations, diets and numbers of strokes differ too much for these studies to settle the question, and the umbrella review rates the stroke evidence low (Landry et al., 2024).

For type 2 diabetes, in the Adventist Health Study 2, 1.08 percent of lacto-ovo vegetarians and 2.12 percent of nonvegetarians reported a new diagnosis over about 2 years, crude proportions; after adjustment, including for body mass index, lacto-ovo vegetarians had lower odds of diabetes, 0.62, from 0.50 to 0.76 (Tonstad et al., 2013). In EPIC-Oxford, the lower risk among vegetarians, with vegans included, 0.63, from 0.54 to 0.74, largely disappeared after adjustment for body mass index, 0.89, from 0.76 to 1.05 (Papier et al., 2019). In a Taiwanese Buddhist cohort followed for a median of 5 years, people who stayed vegetarian had a lower rate of diabetes, 0.65, from 0.46 to 0.92 (Chiu et al., 2018).

Cancer

The largest analysis, published in 2026, pooled individual data from 9 cohorts in the United Kingdom, the United States, Taiwan and India: about 1.8 million people, including 63,147 vegetarians, who ate dairy foods or eggs but no meat or fish, and 8,849 vegans analyzed separately, followed for a median of 16 years. Compared with meat eaters, vegetarians had lower rates of 5 of the 17 cancers examined: pancreas, 0.79, from 0.65 to 0.97; breast, 0.91, from 0.86 to 0.97; prostate, 0.88, from 0.79 to 0.97; kidney, 0.72, from 0.57 to 0.92; and multiple myeloma, a blood cancer, 0.69, from 0.51 to 0.93. They had a higher rate of squamous cell cancer of the esophagus, 1.93, from 1.30 to 2.87. Colorectal cancer did not differ clearly, 1.03, from 0.94 to 1.13 (Dunneram et al., 2026).

The authors interpret these findings cautiously. Only the higher esophageal cancer rate and the lower kidney cancer rate held up both when the first 4 years of follow-up were excluded and when the analysis was limited to people who had never smoked, and the esophageal result rests on 31 cases in 3 British studies. The lower breast cancer rate was confined to women after menopause and was larger before adjustment for body mass index, and the lower pancreatic cancer rate disappeared among never smokers (Dunneram et al., 2026). In the British mortality analysis, vegetarians, with vegans included, also had lower death rates from pancreatic cancer and from cancers of the lymphatic and blood-forming tissues (Appleby et al., 2016).

Body weight, as measured

Vegetarians in these cohorts weighed less on average. In a 2009 analysis of the Adventist Health Study 2, mean body mass index was 25.7 in lacto-ovo vegetarians and 28.8 in nonvegetarians (Tonstad et al., 2009), and in the British cohorts it was about 2 points lower in vegetarians and vegans than in regular meat eaters (Appleby et al., 2016). Adjusting for body mass index weakens several associations on this page, including those for diabetes and hip fracture, which is why the authors report their results with and without that adjustment (Papier et al., 2019; Webster et al., 2023).

Mortality

Whether vegetarians live longer depends on where, and at what age, the question is asked. The longer follow-up of the Adventist Health Study 2, with 88,400 participants, 12,515 deaths and a median of 11.07 years, reported results at modeled ages because the association changed with age. Compared with nonvegetarians, lacto-ovo vegetarians had a hazard ratio for death from any cause of 0.88, from 0.81 to 0.95, estimated at age 65, and 0.97, from 0.92 to 1.02, estimated at age 85; the authors note that the Adventist nonvegetarians are themselves relatively health-conscious (Abris et al., 2024). An earlier report on the same people, after a mean of 5.8 years, gave 0.91, from 0.82 to 1.00; it is the same cohort, not a second study (Orlich et al., 2013).

In 2 British cohorts with 60,310 people and 5,294 deaths, vegetarians analyzed apart from vegans had a hazard ratio of 1.00, from 0.93 to 1.08, compared with regular meat eaters, showing no clear difference (Appleby et al., 2016). Taken together, the longer Adventist follow-up associated lacto-ovo vegetarian eating with lower mortality at age 65, but little clear difference at age 85, and British vegetarians had no clear overall difference from regular meat eaters. These observational findings do not establish that adopting the diet lengthens life.

The Academy’s umbrella review rated the associations of vegetarian, including vegan, diets with lower cardiovascular and coronary heart disease death low in certainty; for cardiovascular death the estimate it relied on was a hazard ratio of 0.92, from 0.85 to 0.99, across 5 cohorts (Landry et al., 2024).

Bone fractures and frailty

In EPIC-Oxford, over 17.6 years, vegetarians had a higher rate of hip fracture than meat eaters, 1.25, from 1.04 to 1.50, after adjustment for body mass index, about 2.9 more cases per 1,000 people over 10 years; the association was stronger without that adjustment and held, slightly weaker, after adjustment for dietary calcium and protein (Tong et al., 2020). The UK Women’s Cohort Study, with 26,318 women followed for 22.3 years, found 1.33, from 1.03 to 1.71 (Webster et al., 2022). UK Biobank, with 413,914 adults followed for 12.5 years, found 1.50, from 1.18 to 1.91, about 3.2 more hip fractures per 1,000 people over 10 years, with lower body mass index explaining about 28 percent of the difference (Webster et al., 2023). That paper’s abstract describes its participants as women, while its title and text describe men and women; this page follows the text.

In a Chinese cohort of 27,917 adults aged 65 and older followed for a median of 3 years, ovo-lacto vegetarians had a higher rate of frailty than omnivores, 1.11, from 1.02 to 1.20. That study counted as ovo-lacto vegetarians people who rarely or never ate meat or fish but ate eggs or milk products, from a short food questionnaire (Y. Huang et al., 2025).

Evidence from other observational studies

Findings on mood are mixed and depend on the population and how depression is measured. A 2021 meta-analysis found higher depression scores in vegetarians than in nonvegetarians, with high heterogeneity between studies; this page read only its abstract (Ocklenburg & Borawski, 2021). Another 2021 meta-analysis, which combined vegetarians and vegans, found higher odds of depression in the 2 studies that recorded it as present or absent, 2.14, from 1.11 to 4.15, but lower anxiety scores, and no clear association with continuous depression scores, stress, wellbeing or cognitive impairment (Iguacel et al., 2021). In a Taiwanese cohort of 10,577 Buddhist volunteers followed from 2005 to 2014, vegetarians, who reported eating no meat or fish, had fewer new depressive disorders recorded in health insurance claims, a hazard ratio of 0.70, from 0.52 to 0.93 (Shen et al., 2021).

A diagnosis recorded in insurance claims is a different outcome from a symptom score, and that cohort's volunteers differ from most clients in religion and habits. All of these studies are observational, so none shows that the diet itself changes mood. The association with eating disorders in young people is described in section 3.

Highlighted studies

These 4 studies carry the most weight for this page: the largest British cohort, the largest North American cohort, the largest pooled analysis of cancer, and the largest randomized trial identified that compared a lacto-ovo vegetarian diet directly with another heart-healthy pattern.

On a narrow screen, scroll the table sideways to see every column.

Highlighted studies for the Vegetarian Diet

Study	Design	Sample size	Duration	Finding	The limitation that matters
Tong et al., 2019, EPIC-Oxford, United Kingdom	Prospective cohort	48,188 adults; 14,422 vegetarians and 1,832 vegans	18.1 years	Vegetarians apart from vegans: ischemic heart disease hazard ratio 0.77, from 0.69 to 0.86; total stroke 1.17, from 1.00 to 1.38. With vegans included: 0.78 and 1.20, about 10 fewer and 3 more cases per 1,000 over 10 years	Health-conscious volunteers; diet group from 4 yes or no questions; the cases per 1,000 come from the combined vegetarian and vegan analysis
Abris et al., 2024, Adventist Health Study 2, United States and Canada	Prospective cohort	88,400 Seventh-day Adventists; 12,515 deaths	Median 11.07 years	Death from any cause, lacto-ovo vegetarians against nonvegetarians: 0.88, from 0.81 to 0.95, estimated at age 65; 0.97, from 0.92 to 1.02, estimated at age 85	A single religious group compared with relatively health-conscious nonvegetarians; diet measured once; the age-specific results come from a statistical model
Dunneram et al., 2026, Cancer Risk in Vegetarians Consortium	Pooled analysis of 9 prospective cohorts	About 1.8 million adults; 63,147 vegetarians	Median 16 years	Lower rates of 5 of 17 cancers, including kidney, 0.72, from 0.57 to 0.92; higher squamous cell esophageal cancer, 1.93, from 1.30 to 2.87	Many comparisons; only 2 results held in both sensitivity analyses; most participants in the United Kingdom and United States
Sofi et al., 2018, CARDIVEG, Italy	Randomized crossover trial, lacto-ovo vegetarian against Mediterranean, both calorie-reduced	118 randomized; 107 analyzed; 100 completed both periods	3 months per diet	Change in LDL cholesterol favored the vegetarian diet by 9.10 mg/dL; change in triglycerides favored the Mediterranean diet by 12.70 mg/dL; no clear difference in weight change detected	Short and open; analyzed only participants who completed a period; no washout between periods is described, though the authors report testing for carryover and not detecting it

Head to head

The CARDIVEG trial in Florence, Italy, randomly assigned 118 adults with overweight and low to moderate cardiovascular risk, 78 percent of them women, to a calorie-reduced lacto-ovo vegetarian diet or a calorie-reduced Mediterranean diet for 3 months, after which each group switched to the other diet. Of the 118, 107 completed at least one period and were analyzed, and 100 completed both. The report does not describe a washout between periods, and its analyses used participants who completed each period. The authors tested for carryover and did not detect it. They also reported unchanged intention-to-treat results, but did not show those analyses (Sofi et al., 2018).

Weight fell on both diets, with no clear difference detected between them. The change in LDL cholesterol favored the vegetarian diet by 9.10 mg/dL, while the change in triglycerides favored the Mediterranean diet by 12.70 mg/dL. Vitamin B12 fell during the vegetarian period and showed a nonsignificant rise during the Mediterranean period; the between-diet test compared changes. The report’s text calls these LDL and triglyceride figures differences in end-of-diet values, but its table shows they are differences in the changes (Sofi et al., 2018). The Mediterranean Diet page carries that diet’s own evidence.

In a 12-week trial in African American adults at risk of type 2 diabetes, a vegetarian pattern, a Mediterranean pattern and a standard healthy pattern produced no clear differences in weight, HbA1c or blood pressure; diet quality scores rose more on the Mediterranean pattern than on the vegetarian one, and 70 percent of the vegetarian group completed the trial against 81 and 86 percent in the other groups (Turner-McGrievy et al., 2023). The 12-week comparison of vegan and lacto-ovo vegetarian diets in type 2 diabetes is described above (Guest et al., 2024); results for vegan diets are on the Vegan Diet page.

A 12-week trial in Poland randomly assigned 90 adults with overweight or obesity to 5 eating patterns, including lacto-ovo vegetarian and Mediterranean diets, with diet plans set 15 percent below energy needs; 85 finished, 17 of them in the lacto-ovo group. It detected no significant between-group differences in glucose, insulin, insulin resistance, lipids or blood pressure. Its small groups and short duration do not establish equivalent effects (Wiśniewska et al., 2025).

Where the evidence is absent

The searches for this page did not identify a randomized trial in generally healthy people designed to measure heart attacks, strokes, cancer or death, or a trial of a vegetarian diet in pregnancy, breastfeeding or childhood. Trials of exercise performance are few, small and only days to weeks long. Because most trials pool lacto-ovo with vegan diets, trial evidence specific to lacto-ovo vegetarians rests on a few small, short trials. The cohort evidence comes mostly from health-conscious British volunteers, Seventh-day Adventists and Taiwanese Buddhists, and studies define a vegetarian in different ways. The stroke findings conflict between Britain and Taiwan, and several cancer findings rest on small numbers of cases. The Academy’s evidence review found no systematic review of vegetarian diets and new cases of high blood pressure or overweight in the general population (Raj et al., 2026).

5. Mechanisms

(optional reading; select the heading to open or close this section)

This section explains how the diet is thought to work in the body. You can skip it. Nothing in the coaching sections depends on it.

Established mechanisms

Blood cholesterol is the clearest link. In randomized trials, vegetarian and vegan diets lowered LDL cholesterol and apolipoprotein B compared with omnivorous diets (Koch et al., 2023). In EPIC-Oxford, vegetarians ate less saturated fat than meat eaters, 10 against 12 percent of energy, and more fruits, vegetables, legumes, soy foods, nuts and fiber, and the authors suggest that lower LDL cholesterol could be part of the reason for their lower rate of heart disease (Tong et al., 2019).

Nutrient absorption is a second established link: iron from plant foods, called nonheme iron, is absorbed less well than iron from meat, about 5 to 12 percent from vegetarian diets against 14 to 18 percent from mixed diets, which is why the iron requirement for vegetarians is set 1.8 times higher (National Institutes of Health Office of Dietary Supplements, 2025a). Phytate in grains and beans binds zinc and reduces its absorption in the same way (National Institutes of Health Office of Dietary Supplements, 2026).

Proposed mechanisms

Body size is one possible explanation. Adjusting observational estimates for body mass index attenuated some associations, including those for diabetes and hip fracture, but this does not establish that body size caused them (Papier et al., 2019; Webster et al., 2023).

Researchers have proposed, without settling, several further explanations. For prostate cancer, the cancer consortium’s authors suggest that lower animal protein intake might lower a growth factor in the blood, insulin-like growth factor I; for squamous cell esophageal cancer, they point to research on low intakes of riboflavin and zinc, which are abundant in animal foods (Dunneram et al., 2026). For bone, lower body weight and lower intakes of calcium and protein have been examined, and adjusting for them reduced but did not remove the higher fracture risk (Tong et al., 2020). For stroke, the Taiwanese researchers explored whether vitamin B12 intake changes the association, as an exploratory analysis (Chiu et al., 2020). None of these has been shown to cause the differences seen in the cohorts.

6. Risks, contraindications and myths

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Warnings from professional or regulatory bodies

The searches for this page did not identify a warning from a professional or regulatory body against a vegetarian diet for adults. The cautions that exist are about planning and life stage. The Academy of Nutrition and Dietetics limits its 2025 position to appropriately planned diets in adults who are not pregnant or breastfeeding, and says guidance for people younger than 18 and for pregnancy and breastfeeding “is outside the scope” of the paper (Raj et al., 2026). The National Institutes of Health Office of Dietary Supplements lists people who follow vegetarian diets among the groups at risk of vitamin B12 deficiency (National Institutes of Health Office of Dietary Supplements, 2025b).

Nutrient gaps

Vitamin B12. Natural food sources of vitamin B12 are limited to animal foods, so vegetarians who eat dairy foods and eggs get some but have a higher risk of deficiency than meat eaters; fortified foods and supplements can substantially reduce that risk (National Institutes of Health Office of Dietary Supplements, 2025b). The Academy describes the high prevalence of B12 deficiency among vegetarians as well documented, notes that higher intakes may be needed especially in older vegetarians, and judges that supplements may be the easiest and most reliable way to ensure adequate status (Raj et al., 2026). In the CARDIVEG trial, vitamin B12 fell during the vegetarian period and showed a nonsignificant rise during the Mediterranean period; the between-diet test compared changes (Sofi et al., 2018).

Iron and zinc. The iron requirement for vegetarians is 1.8 times that for people who eat meat (National Institutes of Health Office of Dietary Supplements, 2025a). The Academy’s evidence review found that vegetarian diets may be associated with lower ferritin, a measure of iron stores, with mixed results and very low certainty, and the paper notes a high prevalence of iron deficiency among premenopausal vegetarian women (Raj et al., 2026). Vegetarians usually have lower zinc intakes and blood levels than people who eat meat; soaking beans, grains and seeds before cooking, and eating fermented foods, may improve absorption (National Institutes of Health Office of Dietary Supplements, 2026).

Vitamin D, calcium, iodine and choline. Vitamin D deficiency is more common in people who follow an ovo-vegetarian or vegan diet (National Institutes of Health Office of Dietary Supplements, 2025c).

The Academy’s position paper was published in 2025 and republished in corrected form in 2026 after a correction to its vitamin D passage; the corrected text says vegetarian and vegan patterns may be associated with lower vitamin D intake and lower blood levels, and that large cohorts show a high incidence of deficiency or insufficiency in vegetarians, including vegans. The same paper reports that calcium intakes of vegetarians are close to those of omnivores and near recommended levels, while vegans’ are lower, and that choline intakes may be well below the adequate intake (Raj et al., 2026). People who eat few or no dairy foods, seafood or eggs may not get enough iodine (National Institutes of Health Office of Dietary Supplements, 2024).

Omega-3 fats and protein. The long-chain omega-3 fats EPA and DHA, found in fish, are low or absent in vegetarian diets without supplements. The body can make them from ALA, found in walnuts and in flax, chia and hemp seeds, though conversion may be limited, and the Academy advises a focus on regular intake of ALA-rich foods, noting that algal supplements are an option if a nutrition professional recommends them (Raj et al., 2026). Protein is not a concern for most adults eating a varied diet with enough food, because protein-rich plant foods together supply all the essential amino acids over the course of a day; older adults are the group the Academy flags for higher protein needs (Raj et al., 2026).

Bone. The hip fracture findings in section 4 are the most consistent health concern for lacto-ovo vegetarians in the cohort data (Tong et al., 2020; Webster et al., 2022, 2023), and the Academy’s evidence review lists lower bone mineral density and higher fracture risk among the potential concerns, with low or very low quality evidence (Raj et al., 2026).

Who should not follow it without medical supervision

Pregnant and breastfeeding women, and children and adolescents, because the current adult position paper leaves these stages to specific guidance and the evidence in them is limited (Raj et al., 2026; Tan et al., 2019; Lotti et al., 2026). Older adults with low bone density, past fractures, frailty or difficulty maintaining protein intake (Webster et al., 2023; Y. Huang et al., 2025; van Oppenraaij et al., 2026). People with chronic kidney disease, whose needs depend on the stage of disease and their care team (Świątek et al., 2023). People taking diabetes medicine that can cause low blood sugar, blood pressure medication, or warfarin (Kahleova et al., 2011; Lee et al., 2020; National Institutes of Health Office of Dietary Supplements, 2021). And people with a history of disordered eating (Sergentanis et al., 2020).

Medication interactions

A coach never adjusts medication. The point of knowing these is to know when to send a client back to the prescriber or pharmacist.

Diabetes medicines. A shift to vegetarian eating can lower blood sugar enough to change medication needs. In the 24-week trial described in section 4, a study physician reduced diabetes medication because of repeated low blood sugar in 43 percent of the vegetarian group and 5 percent of the comparison group (Kahleova et al., 2011). Any client on insulin or a sulfonylurea who makes a substantial change in eating keeps the prescriber informed before making it. A possible low blood sugar episode calls for immediate action under the client’s own diabetes plan; severe symptoms, or an episode the person cannot manage, call for emergency help; afterward the client tells the prescriber about the episode.

Warfarin. Green leafy vegetables are the main dietary source of vitamin K, and people taking warfarin need to keep their vitamin K intake consistent, because sudden changes can increase or decrease the drug’s effect (National Institutes of Health Office of Dietary Supplements, 2021). A client on warfarin who is changing what they eat keeps the prescriber informed.

Signs it is going wrong

Physical signs a coach or family member might notice include ongoing tiredness, an inflamed tongue, palpitations or neurological changes, which are among the symptoms listed for vitamin B12 deficiency, and weakness, fatigue and difficulty concentrating, which can come with iron deficiency anemia (National Institutes of Health Office of Dietary Supplements, 2025a, 2025b). A fracture in an older vegetarian, weight a person loses without meaning to, and slowed growth or underweight in a child are reasons to involve a clinician. Each is a reason to see a clinician, not a diagnosis, and the clinician works out the cause.

Behavior matters as well. A vegetarian diet that keeps narrowing, with more and more foods ruled out, fear of eating anything the person did not prepare, or turning down meals with others, carries more meaning than the vegetarian choice itself. The questions are the same in every case: what the behavior is for, whether it causes distress, whether it is narrowing what the person eats, and whether it is getting in the way of daily life. Where the answers raise a real concern about disordered eating, the coach follows their own referral process.

Myths and where they came from

Myth: vegetarians can’t get enough protein

Where it came from: a long-held belief that animal proteins are superior, which the Academy notes dominated dietary recommendations for years (Raj et al., 2026). What is true: for most adults eating a varied diet with enough food, plant proteins together supply all the essential amino acids, and for active adults and athletes the Academy finds no apparent disadvantage for muscle gain when plant protein reaches at least 1.5 grams per kilogram a day (Raj et al., 2026). Older adults are the exception to watch: in one trial, older adults counseled toward a lacto-ovo vegetarian diet ate less protein than those on an omnivorous diet (van Oppenraaij et al., 2026).

Myth: a vegetarian diet is automatically healthy

Where it came from: the positive findings of vegetarian cohort studies, and marketing for vegetarian products. What is true: the American Heart Association says lacto-ovo vegetarian diets are not inherently health promoting when built mainly on refined grains, sweets and other less healthy plant foods (Gardner et al., 2023), and it urges caution with ultraprocessed plant-based meat alternatives (Lichtenstein et al., 2026). The research on healthful and unhealthful plant-based diets is on the Whole-Food Plant-Based Diet page.

Myth: research has proven that vegetarians live longer

Where it came from: studies of Seventh-day Adventists in the United States, which found lower death rates in vegetarians (Appleby et al., 2016). What is true: in the longer Adventist follow-up, lacto-ovo vegetarians had a lower death rate estimated at age 65, 0.88, from 0.81 to 0.95, but little clear difference at age 85, 0.97, from 0.92 to 1.02, while British vegetarians had 1.00, from 0.93 to 1.08, compared with regular meat eaters (Abris et al., 2024; Appleby et al., 2016). All are observational, and vegetarians in these studies differ from meat eaters in more than diet.

Myth: dairy foods and eggs supply all the vitamin B12 a vegetarian needs

Where it came from: dairy foods and eggs do contain vitamin B12. What is true: vegetarians who eat them still have a higher risk of deficiency (National Institutes of Health Office of Dietary Supplements, 2025b), and the Academy notes that while dairy foods and eggs may supply amounts close to the recommended intake, higher intakes may be needed, especially in older vegetarians (Raj et al., 2026).

7. Key terms

Vegetarian diet

A diet with no meat, poultry or fish, which in most of its forms includes dairy foods, eggs or both.

Lacto-ovo vegetarian

A vegetarian who eats dairy foods and eggs; the most common type.

Lacto-vegetarian

A vegetarian who eats dairy foods but not eggs.

Ovo-vegetarian

A vegetarian who eats eggs but not dairy foods.

Vegan

A diet with no animal foods at all, including dairy foods and eggs.

Pesco-vegetarian, or pescatarian

A diet with no meat or poultry that includes fish; some studies count it among vegetarians, and this page does not.

Semi-vegetarian

A diet that includes meat occasionally; in the Adventist Health Study 2, red meat or poultry at least once a month but less than once a week.

Cohort study

A study that records what people already eat and follows them over time to see what happens to them; it shows associations, not causes.

Randomized controlled trial

A study that assigns people to a diet or a comparison by chance, which is the strongest way to test whether the diet itself causes a result.

Crossover trial

A trial in which each participant follows both diets, one after the other, in random order.

Hazard ratio

The rate of an outcome in one group divided by the rate in another over the same period; 0.80 means a rate 20 percent lower.

Umbrella review

A review that gathers and appraises existing systematic reviews on a question, rather than individual studies.

GRADE

A widely used method for rating how certain a body of evidence is, on a 4-level scale from high to very low.

LDL cholesterol

The cholesterol carried in low-density lipoprotein particles; higher levels are linked with heart disease.

HbA1c

A blood test that reflects average blood sugar over about the previous 3 months.

Hemorrhagic stroke

A stroke caused by bleeding in or around the brain, as opposed to an ischemic stroke caused by a blocked blood vessel.

Nonheme iron

The form of iron in plant foods, which the body absorbs less readily than the heme iron in meat, poultry and fish.

Ferritin

A blood measure of the body’s iron stores.

8. Review questions

1. Name the three types of vegetarian diet and what each one includes. Then explain why a client who says “I’m vegetarian, but I eat fish” is following a different pattern, and name the archive page that covers it.
2. For readers who open section 4: what did the EPIC-Oxford study find for ischemic heart disease and for stroke in vegetarians, in cases per 1,000 people over 10 years, and why does it matter that vegans were counted among the vegetarians?
3. The Adventist Health Study 2 and the British cohorts reached different results on whether vegetarians live longer. Give the Adventist results at ages 65 and 85 and the British result for death from any cause, and give 2 reasons from this page why studies of this design cannot settle the question.
4. A client in her late 60s tells you she has been vegetarian for 40 years, recently broke her wrist, and wonders whether her diet is to blame. Write what you would ask, what you could share with her permission, and where the referral line is.
5. Where did the belief that vegetarians cannot get enough protein come from, and what does the Academy of Nutrition and Dietetics say about it? Which group does the Academy single out for higher protein needs?

9. References

Abris, G. P., Shavlik, D. J., Mathew, R. O., Butler, F. M., Oh, J., Sirirat, R., Sveen, L. E., & Fraser, G. E. (2024). Cause-specific and all-cause mortalities in vegetarian compared with those in nonvegetarian participants from the Adventist Health Study-2 cohort. The American Journal of Clinical Nutrition, 120(4), 907-917. https://doi.org/10.1016/j.ajcnut.2024.07.028

Appleby, P. N., Crowe, F. L., Bradbury, K. E., Travis, R. C., & Key, T. J. (2016). Mortality in vegetarians and comparable nonvegetarians in the United Kingdom. The American Journal of Clinical Nutrition, 103(1), 218-230. https://doi.org/10.3945/ajcn.115.119461

Burke, L. E., Warziski, M., Styn, M. A., Music, E., Hudson, A. G., & Sereika, S. M. (2008). A randomized clinical trial of a standard versus vegetarian diet for weight loss: The impact of treatment preference. International Journal of Obesity, 32(1), 166-176. https://doi.org/10.1038/sj.ijo.0803706

Chiu, T. H. T., Chang, H. R., Wang, L. Y., Chang, C. C., Lin, M. N., & Lin, C. L. (2020). Vegetarian diet and incidence of total, ischemic, and hemorrhagic stroke in 2 cohorts in Taiwan. Neurology, 94(11), e1112-e1121. https://doi.org/10.1212/WNL.0000000000009093

Chiu, T. H. T., Pan, W. H., Lin, M. N., & Lin, C. L. (2018). Vegetarian diet, change in dietary patterns, and diabetes risk: A prospective study. Nutrition & Diabetes, 8(1), Article 12. https://doi.org/10.1038/s41387-018-0022-4

Corichi, M. (2021, July 8). Eight-in-ten Indians limit meat in their diets, and four-in-ten consider themselves vegetarian. Pew Research Center. https://www.pewresearch.org/short-reads/2021/07/08/eight-in-ten-indians-limit-meat-in-their-diets-and-four-in-ten-consider-themselves-vegetarian/

Díaz-Goñi, V., Mesas, A. E., Jiménez-López, E., Olivo-Martins-de-Passos, T., Peral-Martínez, F., Peraile-Huerta, A. M., Visier-Alfonso, M. E., Garrido-Miguel, M., & Bizzozero-Peroni, B. (2026). Are vegetarian and vegan diets associated with eating disorder symptoms? A systematic review and meta-analysis. International Journal of Eating Disorders. Advance online publication. https://doi.org/10.1002/eat.70158

Dunneram, Y., Lee, J. Y., Watling, C. Z., Lawson, I., Parsaeian, M., Fraser, G. E., Butler, F. M., Prabhakaran, D., Shridhar, K., Kondal, D., Mohan, V., Ali, M. K., Narayan, K. M. V., Tandon, N., Tong, T. Y. N., Travis, R. C., Chiu, T. H. T., Lin, M. N., Lin, C. L., . . . Perez-Cornago, A. (2026). Vegetarian diets and cancer risk: Pooled analysis of 1.8 million women and men in nine prospective studies on three continents. British Journal of Cancer, 134(8), 1218-1229. https://doi.org/10.1038/s41416-025-03327-4

Dybvik, J. S., Svendsen, M., & Aune, D. (2023). Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: A systematic review and meta-analysis of prospective cohort studies. European Journal of Nutrition, 62(1), 51-69. https://doi.org/10.1007/s00394-022-02942-8

Elliott, L. J., Keown-Stoneman, C. D. G., Birken, C. S., Jenkins, D. J. A., Borkhoff, C. M., Maguire, J. L., & TARGet Kids! Collaboration. (2022). Vegetarian diet, growth, and nutrition in early childhood: A longitudinal cohort study. Pediatrics, 149(6), Article e2021052598. https://doi.org/10.1542/peds.2021-052598

Gardner, C. D., Vadiveloo, M. K., Petersen, K. S., Anderson, C. A. M., Springfield, S., Van Horn, L., Khera, A., Lamendola, C., Mayo, S. M., & Joseph, J. J. (2023). Popular dietary patterns: Alignment with American Heart Association 2021 dietary guidance: A scientific statement from the American Heart Association. Circulation, 147(22), 1715-1730. https://doi.org/10.1161/CIR.0000000000001146

Guest, N. S., Raj, S., Landry, M. J., Mangels, A. R., Pawlak, R., Senkus, K. E., Handu, D., & Rozga, M. (2024). Vegetarian and vegan dietary patterns to treat adult type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials. Advances in Nutrition, 15(10), Article 100294. https://doi.org/10.1016/j.advnut.2024.100294

Haddad, E. H., & Tanzman, J. S. (2003). What do vegetarians in the United States eat? The American Journal of Clinical Nutrition, 78(3 Suppl.), 626S-632S. https://doi.org/10.1093/ajcn/78.3.626S

Haverstock, K., & Forgays, D. K. (2012). To eat or not to eat. A comparison of current and former animal product limiters. Appetite, 58(3), 1030-1036. https://doi.org/10.1016/j.appet.2012.02.048

Hietavala, E.-M., Puurtinen, R., Kainulainen, H., & Mero, A. A. (2012). Low-protein vegetarian diet does not have a short-term effect on blood acid-base status but raises oxygen consumption during submaximal cycling. Journal of the International Society of Sports Nutrition, 9(1), Article 50. https://doi.org/10.1186/1550-2783-9-50

Hodson, G., & Earle, M. (2018). Conservatism predicts lapses from vegetarian/vegan diets to meat consumption (through lower social justice concerns and social support). Appetite, 120, 75-81. https://doi.org/10.1016/j.appet.2017.08.027

Huang, R.-Y., Huang, C.-C., Hu, F. B., & Chavarro, J. E. (2016). Vegetarian diets and weight reduction: A meta-analysis of randomized controlled trials. Journal of General Internal Medicine, 31(1), 109-116. https://doi.org/10.1007/s11606-015-3390-7

Huang, Y., Jigeer, G., Lv, Y., Wang, K., Ma, X., Zou, J., Xia, R., Shen, X., Shi, X., Li, Y., & Gao, X. (2025). Association between vegetarian diet and risk of frailty in Chinese older adults: A prospective study. BMC Medicine, 23(1), Article 352. https://doi.org/10.1186/s12916-025-04232-6

Iguacel, I., Huybrechts, I., Moreno, L. A., & Michels, N. (2021). Vegetarianism and veganism compared with mental health and cognitive outcomes: A systematic review and meta-analysis. Nutrition Reviews, 79(4), 361-381. https://doi.org/10.1093/nutrit/nuaa030

International Vegetarian Union. (n.d.). 38th IVU World Vegetarian Congress, Dresden (Germany) 2008: 100 years of food revolution. https://ivu.org/congress/2008/article.html

Jones, J. M. (2023, August 24). In U.S., 4% identify as vegetarian, 1% as vegan. Gallup. https://news.gallup.com/poll/510038/identify-vegetarian-vegan.aspx

Kahleova, H., Matoulek, M., Malinska, H., Oliyarnik, O., Kazdova, L., Neskudla, T., Skoch, A., Hajek, M., Hill, M., Kahle, M., & Pelikanova, T. (2011). Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with type 2 diabetes. Diabetic Medicine, 28(5), 549-559. https://doi.org/10.1111/j.1464-5491.2010.03209.x

Koch, C. A., Kjeldsen, E. W., & Frikke-Schmidt, R. (2023). Vegetarian or vegan diets and blood lipids: A meta-analysis of randomized trials. European Heart Journal, 44(28), 2609-2622. https://doi.org/10.1093/eurheartj/ehad211

Landry, M. J., Senkus, K. E., Mangels, A. R., Guest, N. S., Pawlak, R., Raj, S., Handu, D., & Rozga, M. (2024). Vegetarian dietary patterns and cardiovascular risk factors and disease prevention: An umbrella review of systematic reviews. American Journal of Preventive Cardiology, 20, Article 100868. https://doi.org/10.1016/j.ajpc.2024.100868

Lee, K. W., Loh, H. C., Ching, S. M., Devaraj, N. K., & Hoo, F. K. (2020). Effects of vegetarian diets on blood pressure lowering: A systematic review with meta-analysis and trial sequential analysis. Nutrients, 12(6), Article 1604. https://doi.org/10.3390/nu12061604

Leitzmann, C. (2014). Vegetarian nutrition: Past, present, future. The American Journal of Clinical Nutrition, 100(Suppl. 1), 496S-502S. https://doi.org/10.3945/ajcn.113.071365

Lichtenstein, A. H., Khera, A., Anderson, C. A. M., Appel, L. J., DeSilva, D. M., Gardner, C., Hu, F. B., Jones, D. W., Petersen, K. S., & American Heart Association. (2026). 2026 dietary guidance to improve cardiovascular health: A scientific statement from the American Heart Association. Circulation, 153(18), e1285-e1295. https://doi.org/10.1161/CIR.0000000000001435

Lotti, S., Panizza, G., Martini, D., Marx, W., Beasley, J. M., Colombini, B., & Dinu, M. (2026). Lacto-ovo-vegetarian and vegan diets in children and adolescents: A systematic review and meta-analysis of nutritional and health outcomes. Critical Reviews in Food Science and Nutrition, 66(13), 2453-2473. https://doi.org/10.1080/10408398.2025.2572983

Melina, V., Craig, W., & Levin, S. (2016). Position of the Academy of Nutrition and Dietetics: Vegetarian diets. Journal of the Academy of Nutrition and Dietetics, 116(12), 1970-1980. https://doi.org/10.1016/j.jand.2016.09.025

National Institutes of Health Office of Dietary Supplements. (2021, March 29). Vitamin K: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/

National Institutes of Health Office of Dietary Supplements. (2024, November 5). Iodine: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

National Institutes of Health Office of Dietary Supplements. (2025a, September 4). Iron: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/

National Institutes of Health Office of Dietary Supplements. (2025b, July 2). Vitamin B12: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/

National Institutes of Health Office of Dietary Supplements. (2025c, June 27). Vitamin D: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

National Institutes of Health Office of Dietary Supplements. (2026, January 6). Zinc: Fact sheet for health professionals. https://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/

Nebl, J., Haufe, S., Eigendorf, J., Wasserfurth, P., Tegtbur, U., & Hahn, A. (2019). Exercise capacity of vegan, lacto-ovo-vegetarian and omnivorous recreational runners. Journal of the International Society of Sports Nutrition, 16(1), Article 23. https://doi.org/10.1186/s12970-019-0289-4

Ocklenburg, S., & Borawski, J. (2021). Vegetarian diet and depression scores: A meta-analysis. Journal of Affective Disorders, 294, 813-815. https://doi.org/10.1016/j.jad.2021.07.098

Orlich, M. J., Singh, P. N., Sabaté, J., Jaceldo-Siegl, K., Fan, J., Knutsen, S., Beeson, W. L., & Fraser, G. E. (2013). Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Internal Medicine, 173(13), 1230-1238. https://doi.org/10.1001/jamainternmed.2013.6473

Papier, K., Appleby, P. N., Fensom, G. K., Knuppel, A., Perez-Cornago, A., Schmidt, J. A., Tong, T. Y. N., & Key, T. J. (2019). Vegetarian diets and risk of hospitalisation or death with diabetes in British adults: Results from the EPIC-Oxford study. Nutrition & Diabetes, 9(1), Article 7. https://doi.org/10.1038/s41387-019-0074-0

Raj, S., Guest, N. S., Landry, M. J., Mangels, A. R., Pawlak, R., & Rozga, M. (2026). Vegetarian dietary patterns for adults: A position paper of the Academy of Nutrition and Dietetics. Journal of the Academy of Nutrition and Dietetics, 126(3), Article 156227. https://doi.org/10.1016/j.jand.2025.156227

Reis, D., Schwermer, M., Nowak, L., Naami, N., Zuzak, T. J., & Längler, A. (2025). Vegetarian diet and dietary intake, health, and nutritional status in infants, children, and adolescents: A systematic review. Nutrients, 17(13), Article 2183. https://doi.org/10.3390/nu17132183

Scarborough, P., Clark, M., Cobiac, L., Papier, K., Knuppel, A., Lynch, J., Harrington, R., Key, T., & Springmann, M. (2023). Vegans, vegetarians, fish-eaters and meat-eaters in the UK show discrepant environmental impacts. Nature Food, 4(7), 565-574. https://doi.org/10.1038/s43016-023-00795-w

Sergentanis, T. N., Chelmi, M. E., Liampas, A., Yfanti, C. M., Panagouli, E., Vlachopapadopoulou, E., Michalacos, S., Bacopoulou, F., Psaltopoulou, T., & Tsitsika, A. (2020). Vegetarian diets and eating disorders in adolescents and young adults: A systematic review. Children, 8(1), Article 12. https://doi.org/10.3390/children8010012

Shen, Y.-C., Chang, C.-E., Lin, M.-N., & Lin, C.-L. (2021). Vegetarian diet is associated with lower risk of depression in Taiwan. Nutrients, 13(4), Article 1059. https://doi.org/10.3390/nu13041059

Sofi, F., Dinu, M., Pagliai, G., Cesari, F., Gori, A. M., Sereni, A., Becatti, M., Fiorillo, C., Marcucci, R., & Casini, A. (2018). Low-calorie vegetarian versus Mediterranean diets for reducing body weight and improving cardiovascular risk profile: CARDIVEG Study (Cardiovascular Prevention With Vegetarian Diet). Circulation, 137(11), 1103-1113. https://doi.org/10.1161/CIRCULATIONAHA.117.030088

Springmann, M., Clark, M. A., Rayner, M., Scarborough, P., & Webb, P. (2021). The global and regional costs of healthy and sustainable dietary patterns: A modelling study. The Lancet Planetary Health, 5(11), e797-e807. https://doi.org/10.1016/S2542-5196(21)00251-5

Świątek, Ł., Jeske, J., Miedziaszczyk, M., & Idasiak-Piechocka, I. (2023). The impact of a vegetarian diet on chronic kidney disease (CKD) progression: A systematic review. BMC Nephrology, 24(1), Article 168. https://doi.org/10.1186/s12882-023-03233-y

Tan, C., Zhao, Y., & Wang, S. (2019). Is a vegetarian diet safe to follow during pregnancy? A systematic review and meta-analysis of observational studies. Critical Reviews in Food Science and Nutrition, 59(16), 2586-2596. https://doi.org/10.1080/10408398.2018.1461062

Tong, T. Y. N., Appleby, P. N., Armstrong, M. E. G., Fensom, G. K., Knuppel, A., Papier, K., Perez-Cornago, A., Travis, R. C., & Key, T. J. (2020). Vegetarian and vegan diets and risks of total and site-specific fractures: Results from the prospective EPIC-Oxford study. BMC Medicine, 18(1), Article 353. https://doi.org/10.1186/s12916-020-01815-3

Tong, T. Y. N., Appleby, P. N., Bradbury, K. E., Perez-Cornago, A., Travis, R. C., Clarke, R., & Key, T. J. (2019). Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: Results from the prospective EPIC-Oxford study. BMJ, 366, Article l4897. https://doi.org/10.1136/bmj.l4897

Tonstad, S., Butler, T., Yan, R., & Fraser, G. E. (2009). Type of vegetarian diet, body weight, and prevalence of type 2 diabetes. Diabetes Care, 32(5), 791-796. https://doi.org/10.2337/dc08-1886

Tonstad, S., Stewart, K., Oda, K., Batech, M., Herring, R. P., & Fraser, G. E. (2013). Vegetarian diets and incidence of diabetes in the Adventist Health Study-2. Nutrition, Metabolism and Cardiovascular Diseases, 23(4), 292-299. https://doi.org/10.1016/j.numecd.2011.07.004

Turner-McGrievy, G. M., Wilson, M. J., Carswell, J., Okpara, N., Aydin, H., Bailey, S., Davey, M., Hutto, B., Wilcox, S., Friedman, D. B., Sarzynski, M. A., & Liese, A. D. (2023). A 12-week randomized intervention comparing the Healthy US, Mediterranean, and Vegetarian dietary patterns of the US Dietary Guidelines for changes in body weight, hemoglobin A1c, blood pressure, and dietary quality among African American adults. The Journal of Nutrition, 153(2), 579-587. https://doi.org/10.1016/j.tjnut.2022.11.020

van Oppenraaij, S. L., Weijs, P. J. M., & Verlaan, S. (2026). Effects of a self-selected vegetarian vs. omnivorous diet on protein intake and muscle mass in older adults during resistance exercise: The IMPACT randomized controlled trial. The American Journal of Clinical Nutrition. Advance online publication. https://doi.org/10.1016/j.ajcnut.2026.101533

Wang, T., Kroeger, C. M., Cassidy, S., Mitra, S., Ribeiro, R. V., Jose, S., Masedunskas, A., Senior, A. M., & Fontana, L. (2023). Vegetarian dietary patterns and cardiometabolic risk in people with or at high risk of cardiovascular disease: A systematic review and meta-analysis. JAMA Network Open, 6(7), Article e2325658. https://doi.org/10.1001/jamanetworkopen.2023.25658

Webster, J., Greenwood, D. C., & Cade, J. E. (2022). Risk of hip fracture in meat-eaters, pescatarians, and vegetarians: Results from the UK Women’s Cohort Study. BMC Medicine, 20(1), Article 275. https://doi.org/10.1186/s12916-022-02468-0

Webster, J., Greenwood, D. C., & Cade, J. E. (2023). Risk of hip fracture in meat-eaters, pescatarians, and vegetarians: A prospective cohort study of 413,914 UK Biobank participants. BMC Medicine, 21(1), Article 278. https://doi.org/10.1186/s12916-023-02993-6

Wiśniewska, K., Okręglicka, K. M., Paskudzka, M., Jagielska, A. M., Bober, J., Oczkowski, M., Ciepiela, O., & Nitsch-Osuch, A. (2025). The VEGPREV study: Effectiveness of four plant-based diets on weight loss, metabolic syndrome components and appetitive traits in overweight and obese individuals: A randomized controlled trial. Frontiers in Nutrition, 12, Article 1677496. https://doi.org/10.3389/fnut.2025.1677496

Evidence rating and review record

Each row identifies the method, source, outcome or recommendation, and comparison being rated. Ratings from different tools are not interchangeable. The source is either a named published review or this page's own judgment. The rating in the banner is for this diet's main claimed outcome or recommendation, and the banner names the tool that produced it. A high rating means the research is solid; it does not mean the diet is right for everyone, and it does not mean a coach should recommend it.

Every rated row on this page was rated with GRADE, which uses the same 4-level scale as the clinical guidelines you will meet in practice. High means further research is very unlikely to change the conclusion. Moderate means further research may change it. Low means further research is likely to change it. Very low means the conclusion is uncertain. GRADE rates each outcome separately, so a diet can be high for one outcome and very low for another.

Three things about this table matter before reading it. Most published rows rate vegetarian diets with vegans included, because that is how the reviews pooled the studies; they are not ratings for lacto-ovo vegetarians alone, and each row says what was combined. The cohort rows rate associations, not the effect of choosing the diet. And 2 rows record outcomes this page did not rate, with the reason. One row, LDL cholesterol in the CARDIVEG trial, is marked provisional because its precision judgment is not yet complete.

Ratings marked as this page's own judgment were assigned from the evidence given in each row's reasons; ratings from a published review are reported exactly as that review published them.

On a narrow screen, scroll the table sideways to see every column.

Evidence ratings, their sources and reasons

Outcome	Certainty	Who rated it, and for which comparison	Why it is rated this way
Cardiovascular disease, new cases (deaths used where new cases were not reported)	Moderate	GRADE. Landry et al., 2024, an umbrella review by the Academy of Nutrition and Dietetics. Vegetarian diets, with vegans included, against nonvegetarian diets, in generally healthy adults, 8 cohorts with 621,282 people followed 5 to 28 years, as pooled by Dybvik et al., 2023	As published. Relative risk 0.85, from 0.79 to 0.92. The review started this evidence at high because the underlying meta-analysis assessed bias with ROBINS-I, and lowered it 1 level for risk of bias; it did not lower it for inconsistency, with an I² of 68 percent, or for indirectness, imprecision or publication bias. This page notes 2 points the published rating does not address: the pooled estimate used the Adventist Health Study 2’s combined vegetarian group, which included fish eaters and occasional meat eaters, and it counted deaths as new cases where a cohort lacked incidence data. This is an association, not the effect of adopting the diet.
Coronary heart disease, new cases (deaths used where new cases were not reported)	Moderate	GRADE. Landry et al., 2024. Same comparison and cohorts as the row above	As published. Relative risk 0.79, from 0.71 to 0.88, with an I² of 67 percent. Started at high and lowered 1 level for risk of bias, as above, with the same 2 points noted.
Total stroke, new cases	Low	GRADE. Landry et al., 2024. Vegetarian diets, with vegans included, against nonvegetarian diets, 12 cohorts with 770,867 people	As published. Relative risk 0.90, from 0.77 to 1.05. Lowered 1 level for risk of bias and 1 for imprecision, because the interval includes both lower and higher risk. Single cohorts disagree: higher stroke in EPIC-Oxford, lower in 2 Taiwanese cohorts (Chiu et al., 2020; Tong et al., 2019).
Death from cardiovascular disease	Low	GRADE. Landry et al., 2024. Vegetarian diets, with vegans included, against nonvegetarian diets, 5 cohorts with 144,247 people	As published. Hazard ratio 0.92, from 0.85 to 0.99. Cohort evidence starts low, and the review made no further deductions.
Death from coronary heart disease	Low	GRADE. Landry et al., 2024. Vegetarian diets, with vegans included, against nonvegetarian diets, 7 cohorts with 197,377 people	As published. Hazard ratio 0.76, from 0.68 to 0.85. Started low for observational design, with no further deductions; the review chose not to lower it for the health-conscious makeup of the cohorts, as an earlier review had, because that behavior is the one being studied.
HbA1c, adults with type 2 diabetes	Moderate	GRADE. Guest et al., 2024, a systematic review by the Academy of Nutrition and Dietetics. Vegetarian diets against therapeutic or usual nonvegetarian diets, 5 randomized trials, 12 to 74 weeks; 4 tested vegan diets and 1 a diet labeled lacto-ovo vegetarian	As published. Mean difference 0.40 percentage points lower, from 0.21 to 0.59 lower, with no heterogeneity. Randomized trials start high; lowered 1 level for small sample sizes. Not a rating for lacto-ovo vegetarian diets alone: the 1 lacto-ovo trial, on its own, did not exclude no effect.
LDL cholesterol, adults with or at high risk of cardiovascular disease	Moderate	GRADE. Wang et al., 2023. Vegetarian diets, vegan, lacto-ovo and lacto-vegetarian combined, against all comparison diets, 19 randomized trials with 1,661 participants, 8 weeks to 2 years	As published. Mean difference 6.6 mg/dL lower, from 3.1 to 10.1 lower. In the review’s supplement, randomized trials started at high and were lowered 1 level for inconsistency, with an I² of 67 percent; the authors did not lower the rating for risk of bias, although no trial could blind participants, or for indirectness, imprecision or publication bias.
Systolic blood pressure, adults with or at high risk of cardiovascular disease	Low	GRADE. Wang et al., 2023. Same comparison, 14 randomized trials with 955 participants	As published. Mean difference 0.1 mmHg lower, from 2.8 lower to 2.6 higher. Started at high and lowered 1 level for inconsistency, with an I² of 65 percent, and 1 for imprecision, which the authors based on the interval including no effect; not lowered for risk of bias, indirectness or publication bias. The imprecision reason is the authors’; this page does not treat an interval that includes no effect as imprecise by rule.
LDL cholesterol, calorie-reduced lacto-ovo vegetarian against calorie-reduced Mediterranean diet, adults with overweight and low to moderate cardiovascular risk, 3 months	Low	GRADE. This page’s own judgment. 1 randomized crossover trial, 118 randomized and 107 analyzed (Sofi et al., 2018)	Randomized trials start high. The row rates the difference in LDL cholesterol change between the 2 diets, 9.10 mg/dL in favor of the vegetarian diet. Low (provisional pending completion of the imprecision assessment). Risk of bias is serious because the reported analysis selected participants completing each diet period; the authors’ unchanged intention-to-treat results were not shown. That participants knew their diet is not by itself a reason to lower the rating for a laboratory measure. The available report does not supply a verified confidence interval for the between-diet change used here. A numerical threshold for an important LDL difference and a defensible interval or information-size assessment are still needed to complete the precision judgment. Inconsistency and publication bias cannot be judged from 1 trial. Not lowered for indirectness, because the row is limited to this comparison and population.
Death from any cause, lacto-ovo vegetarians against nonvegetarians or regular meat eaters	Very low	GRADE. This page’s own judgment. 2 cohort analyses that report vegetarians who eat dairy foods or eggs apart from vegans: the longer Adventist Health Study 2 follow-up, 88,400 people over a median of 11.07 years, and 2 British cohorts, 60,310 people (Abris et al., 2024; Appleby et al., 2016). The earlier Adventist report covers the same people and is not counted again	Cohort studies start low. The question rated is whether lacto-ovo vegetarians have a meaningfully lower death rate, taken as a hazard ratio of 0.90 or lower, because smaller differences are within what other differences between the groups could produce. Lowered 1 level for inconsistency: the Adventist estimate at age 65, 0.88, from 0.81 to 0.95, points to a meaningful difference, while the Adventist estimate at age 85, 0.97, from 0.92 to 1.02, and the British estimate, 1.00, from 0.93 to 1.08, do not; age and population may explain this, but neither explanation is established. Not lowered further for risk of bias, since residual confounding is the reason for the low start. Adventist diet was measured at baseline; the British analysis updated diet groups and covariates during follow-up when questionnaires were available. Both analyses remain vulnerable to residual confounding and dietary measurement error; the direction of those biases cannot be assumed. Not lowered for indirectness, since both analyses report the group this row rates. The age-65 interval includes both reductions larger than 10 percent and smaller reductions, so it does not establish a benefit of that size. The older Adventist and British results do not support a consistent mortality reduction of at least 10 percent. These limitations leave the broad mortality conclusion at Very low. Publication bias cannot be judged from 2 analyses. Not raised: no large effect and no dose-response analysis.
Hip fracture, vegetarians against regular meat eaters, British adults	Low	GRADE. This page’s own judgment. 3 prospective cohorts: EPIC-Oxford, 17.6 years; the UK Women’s Cohort Study, 22.3 years; UK Biobank, 12.5 years (Tong et al., 2020; Webster et al., 2022, 2023)	Cohort studies start low. Not lowered for inconsistency: hazard ratios of 1.25, 1.33 and 1.50 all point the same way. Not lowered for imprecision: each interval excludes no difference, from 1.04, 1.03 and 1.18 at their lower ends, which is enough precision for a higher rate, although the upper ends, 1.50, 1.71 and 1.91, leave the size of the difference uncertain. Not lowered for indirectness, because the row is limited to British adults; other populations may differ. Not lowered further for risk of bias, since residual confounding is already reflected in the low start. Publication bias was not demonstrated, but it cannot be judged well from 3 cohorts. Not raised: the effects are not large and no dose-response analysis was reported. This is a higher rate of fracture, not proof that the diet causes fractures; lower body mass index explains part of it.
Cancer at specific sites	Not rated	This page’s own judgment	The pooled consortium analysis compared vegetarians with meat eaters for 17 cancers and reported several higher and lower rates, but only 2 held in both of its sensitivity analyses, and some rest on few cases (Dunneram et al., 2026). With this many comparisons from one analysis, this page reports the estimates in section 4 without assigning certainty labels to individual sites.
Body weight	Not rated	This page’s own judgment	The trials differ in diet, comparison, calorie restriction and length, and this page makes no claim that a vegetarian diet changes body weight. The measurements are reported in section 4, in each study’s own numbers (Burke et al., 2008; R.-Y. Huang et al., 2016; Sofi et al., 2018).

How this archive talks about weight. This page reports what studies measured, including body weight, and does not treat weight change as a goal or as a measure of a diet's success. Weight a person loses without meaning to can be a sign of a health problem, and where it is, the page names it as a reason to see a clinician. People are described the way the study described them.

Last reviewed: Reviewed and approved by James Peth, MS, MPH, PhD, on October 6, 2026, after a combined final review of the third batch of 5 archive pages, the plant-based family, the repairs it asked for, a focused recheck and a repair confirmation. Written October 4, 2026. Several sources could be read only as abstracts; claims drawn from them stay within what each abstract says, and none of them carries a rating. One rating, LDL cholesterol in the CARDIVEG trial, is marked provisional because its precision judgment is not yet complete.

Updated October 21, 2026: The American Heart Association is now named as an author of its 2026 dietary guidance statement (Lichtenstein et al., 2026), as the publisher's citation credits it. No content changed.

Next scheduled review: August 2027. Pages built on annual guidance are rechecked each year. The federal fact sheets cited on this page are updated from time to time and should be rechecked first, along with the Academy of Nutrition and Dietetics position paper, which is in effect until December 31, 2032.

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Diet Reference Archive | One James

Prepared by James Peth, MS, MPH, PhD

© 2026–2027 One James. All rights reserved.

This page is for education and coaching practice. It is not medical or dietary advice.