Vegetarian Diet

Religious and ethical roots in South Asia

A paper by an Adventist theologian, presented in 2002, surveys what several religions teach about meat. It reports that in the Hindu tradition meat was eaten and animals were sacrificed in the Vedic period, that some sages advocated a meatless diet from about the sixth or seventh century BC, and that restrictions on eating beef grew over the following centuries. It dates Jainism and Buddhism to the sixth century BC and places strong emphasis on ahimsa, or non-injury, in both.

The same paper describes Jain teaching as forbidding meat, alcohol and honey, and states that meat is never eaten, even from an animal that died naturally. It reports that Buddhist practice differs by branch: in the Theravada tradition meat-eating is largely condoned for lay people and for monks who accept food that was not slaughtered for them, whereas Mahayana monks in China have kept to strict vegetarianism. The paper comes from a faith-based journal, so its framing should be read with that in mind.

Organized vegetarianism in nineteenth-century England

The Vegetarian Society's own history states that the earliest known use of the word vegetarian was in an 1842 issue of the Healthian Journal, published by the Alcott House school. It reports that a society to promote vegetarianism was proposed in a letter of April 1847 and that the Vegetarian Society held its first meeting on 30 September 1847 at Ramsgate, with Joseph Brotherton, a member of Parliament, in the chair. The sources reviewed do not cover earlier Greek traditions such as the Pythagorean diet, so this page makes no claim about them.

Seventh-day Adventist health message

A review of Adventist influence on diet describes health reform as a feature of the church from its mid-nineteenth-century beginnings in the United States. It places the church's official organization in 1863 and the Western Reform Institute at Battle Creek, Michigan, in 1866, and credits Ellen G. White, a founding leader, with writing extensively on diet. The review also notes that Loma Linda University has conducted much of the church's research, including the Adventist Health Studies.

The 2002 religions survey states that nearly half of Seventh-day Adventists abstain from meat, and that White argued for a return to a diet of grains, fruits, nuts and vegetables. That figure is an authored estimate from an Adventist scholar rather than a census count, and the 2018 review does not give a percentage.

Types of vegetarian diet

Usage varies between sources. A review from the Oxford cohort defines vegetarian eating as plant-based eating plus dairy products and eggs, and vegan eating as entirely plant-based. The Adventist Health Study-2 mortality analysis grouped participants into five patterns: nonvegetarian, semivegetarian, pescovegetarian, lacto-ovovegetarian and vegan.

A pediatric review orders children's diets by increasing restriction as flexitarian, lacto-ovo-vegetarian, lacto-vegetarian, pescatarian, vegan and macrobiotic. Because pescatarian and flexitarian patterns include fish or some meat, they are often grouped with vegetarian diets in research even though strict usage would exclude them. Findings from one pattern should not be applied to another.

Relation to other Machipedia pages

This page belongs to the Dietary Approaches family on Machipedia, which compares eating patterns. Vegan Diet and Plant-Based Diet have separate pages, as does the Mediterranean Diet, which includes fish and some meat. The professional fields of Dietetics and Nutritional Therapy are described on their own pages. Sources reviewed here use plant-based as an umbrella label that sometimes includes vegetarian and vegan diets together.

Food patterns described in dietetic positions

The Academy of Nutrition and Dietetics position paper describes vegetarian diets as low in saturated fat and high in vegetables, fruits, whole grains, legumes, soy products, nuts and seeds, all of which are rich in fiber and phytochemicals. It states that these characteristics are linked to lower total and LDL cholesterol and better serum glucose control, and that vegans need a reliable source of vitamin B12 such as fortified foods or supplements.

Planning and professional involvement

A pediatric review states that providing an adequate lacto-ovo-vegetarian diet is relatively easy, while more restrictive diets may be challenging to maintain. It recommends that the health consequences of a chosen diet be discussed with families and adolescents and that nutrition knowledge among health professionals be improved. A systematic review of nutrient intake in adults concluded that nutrient gaps occur in meat-based diets as well as in vegetarian and vegan ones.

Reasons people give for following the diet

A pediatric review states that populations in the West increasingly restrict meat and other animal products for reasons related to health or ethics, and that in many countries restrictions are common for cultural, religious or socioeconomic reasons. The religious and ethical rationales described by Jain, Hindu, Buddhist and Adventist sources center on non-injury to animals or on a belief about the intended human diet.

Health and environmental claims

The Academy of Nutrition and Dietetics position paper states that appropriately planned vegetarian diets may provide health benefits in the prevention and treatment of certain diseases, and that vegetarians and vegans are at reduced risk of ischemic heart disease, type 2 diabetes, hypertension, certain cancers and obesity. It also states that plant-based diets use fewer natural resources than diets rich in animal products. These are the paper's conclusions from the literature it reviewed, and the research section below describes the underlying study types and their limits.

Prospective cohort studies

The Adventist Health Study-2 followed 88,400 participants for 971,424 person-years, with mortality ascertained through 2015 and 12,515 deaths. Compared with nonvegetarians, vegetarians had lower all-cause mortality at age 65 (hazard ratio 0.89, 95% CI 0.83 to 0.95) but not at age 85 (0.98, 0.91 to 1.04). Lower risks were reported for ischemic heart disease, diabetes and renal failure, while vegetarians at age 85 had higher estimated stroke mortality (1.17, 1.02 to 1.33) and dementia mortality (1.13, 1.00 to 1.27). The authors state that the findings need further support.

A review of the EPIC-Oxford cohort reports that vegetarians had lower risks of ischemic heart disease, diabetes, diverticular disease, kidney stones and cataracts, possibly some cancers, and higher risks of stroke, mainly hemorrhagic, and of bone fractures, compared with meat-eaters.

Systematic reviews of observational studies

A 2022 meta-analysis of 13 prospective cohorts with 844,175 participants found lower cardiovascular disease (relative risk 0.85, 95% CI 0.79 to 0.92) and ischemic heart disease (0.79, 0.71 to 0.88) in vegetarians than nonvegetarians, but no clear association with stroke (0.90, 0.77 to 1.05). Risk of bias was rated moderate in eight cohorts and serious in five. The authors judged the cardiovascular associations probably causal under World Cancer Research Fund criteria, a judgment that rests on observational data.

An earlier meta-analysis of 86 cross-sectional and 10 cohort studies reported lower body mass index, cholesterol and glucose in vegetarians and vegans, lower ischemic heart disease risk (relative risk 0.75) and lower total cancer incidence (0.92), but no significant association with all-cause mortality, cancer mortality or specific cancer types.

Randomized and interventional trials

A meta-analysis of nine randomized trials in people with diabetes, lasting at least three weeks and enrolling 664 participants, found that vegetarian dietary patterns lowered glycated hemoglobin by 0.29 percentage points, LDL cholesterol and body weight (about 2.15 kg), with no significant effect on blood pressure, HDL cholesterol or triglycerides. The authors rated overall certainty as moderate, and low for some outcomes. These trials enrolled people with diabetes only.

A broader systematic review of 32 interventional studies of plant-based, vegan or vegetarian diets reported evidence for short- to moderate-term effects, up to 24 months, on weight status, energy metabolism and systemic inflammation. It found little interventional evidence on cognition and concluded that a causal effect on brain health had not been demonstrated. It did not separate vegetarian from vegan diets.

Limits of the evidence

Cohort comparisons depend on self-reported diet, and people who choose vegetarian eating may differ in smoking, activity and other habits that adjustment cannot fully remove. The Adventist cohorts also draw on a religious community with many health-oriented practices. None of the sources reviewed reports long-term randomized outcomes such as heart attacks or deaths.

Nutrient considerations

A systematic review of 141 studies from 2000 to January 2020 found that protein intake was lower on plant-based diets than in meat-eaters but within recommended levels. Intake and status of vitamin B12, vitamin D, iron, zinc, iodine and calcium were generally lower, and EPA and DHA omega-3 intake was lower. The review also reported nutrient inadequacies in meat-based diets, including fiber, folate, vitamin D and calcium. It pooled vegetarian and vegan groups, and vegans showed the lowest B12, calcium and iodine intake.

Pregnancy, infancy, childhood and adolescence

The Academy of Nutrition and Dietetics states that appropriately planned vegetarian diets are suitable for all stages of the life cycle, including pregnancy, lactation, infancy, childhood and adolescence. A pediatric review is more cautious: it reports that the more restrictive the diet and the younger the child, the greater the risk of nutritional deficiency, naming vitamin B12, iron, zinc, calcium, long-chain omega-3 fatty acids, protein and energy, especially for pregnant and nursing women, infants and young children.

The pediatric review adds that evidence on children is scarce compared with adults, and that its author discourages vegan and macrobiotic diets in pregnancy, lactation and early childhood without careful attention to blood testing and supplementation. The two positions differ in emphasis, and neither source gives individual advice.

Older adults

The Adventist analysis found higher estimated stroke and dementia mortality among vegetarians at age 85, and EPIC-Oxford reviewers report a higher fracture risk in vegetarians. The reviews report these as associations that need further study. The Academy of Nutrition and Dietetics lists older adulthood among the life stages for which appropriately planned vegetarian diets are suitable.

Eating disorders and mental health

A 2025 review of orthorexia nervosa and plant-based diets states that it is unclear whether vegetarianism raises the risk of developing the condition or whether it attracts people who already have it, though a positive association was shown. It warns against labeling people as disordered solely because they follow a vegetarian diet. A 2025 commentary concluded that, if the diet is nutritionally adequate, avoiding animal foods has no significant effect on physical or mental health. Both are narrative reviews and do not establish cause.

Anyone with a history of disordered eating, a medical condition, or an upcoming pregnancy may wish to involve a registered dietitian or physician. This page does not replace individual advice, and dietary change should not delay or replace needed medical care.