Vegan Diet

The Vegan Society and the coining of the word

The Vegan Society says it began in November 1944, when six non-dairy vegetarians, among them Donald Watson and Elsie Shrigley, met to discuss vegetarian diets and lifestyles. The society's history page states that Watson coined the word 'vegan' after the group decided it needed a shorter term than 'non-dairy vegetarians'. It records him later describing the word as marking the beginning and end of 'vegetarian'. These accounts come from the organization itself.

The same page notes that two members suggested the society be called Allvega and its magazine Allvegan. The page does not say whether the magazine adopted that name, and the sources reviewed here do not settle it.

From a diet to a defined philosophy

The Vegan Society's definition page reports that in 1949 Leslie J. Cross observed the society lacked a formal definition and proposed one centered on the emancipation of animals from human exploitation. The society's objects and wording were refined over the following decades, and it states that its current definition had been adopted by winter 1988.

Today the society describes veganism as a philosophy and way of living that seeks to exclude, as far as possible and practical, exploitation of and cruelty to animals for food, clothing or any other purpose. In diet terms it means avoiding all products wholly or partly derived from animals. The sources reviewed do not trace the diet's earlier history before 1944, so this page does not do so either.

Vegan, vegetarian and plant-based

A vegan diet excludes meat, fish, eggs, dairy and other animal-derived products. A Cochrane review of vegan dietary patterns defined the pattern as one that excludes meat, fish, eggs, dairy and honey, and a systematic review of disordered eating used the same exclusion of all animal-derived products. Vegetarian diets, by contrast, vary and may include dairy or eggs. The Machipedia page Vegetarian Diet covers that broader family.

The term 'plant-based' is used inconsistently. Researchers from the EPIC-Oxford study note it is sometimes used for omnivorous diets with a small component of animal foods, and state that in their own review they take it to mean vegetarian or vegan eating. The separate page Plant-Based Diet covers the looser usage.

Ethical veganism and dietary veganism

The Vegan Society presents veganism as a philosophy that extends beyond food to clothing and other uses of animals. A person can follow a vegan diet for health, environmental or other reasons without adopting that wider philosophy, and the research below usually studies the diet alone, often in short interventions with provided meals or in cohorts classified by food-frequency questionnaires.

The eating-disorder literature also separates motivations. A systematic review reports that dietary motivation, such as health compared with ethical or ideological reasons, did not appear to influence rates of disordered eating in the studies it examined. The review also notes many studies combine vegetarians and vegans in one group, which can mask differences.

What the pattern involves

The Academy of Nutrition and Dietetics position statement describes the characteristic features of vegetarian and vegan diets as low intake of saturated fat and high intakes of vegetables, fruits, whole grains, legumes, soy products, nuts and seeds. The authors attribute lower total and LDL cholesterol and better glucose control in part to these features. The abstract does not describe particular menus, and this page does not give meal plans.

A dietary pattern defined by exclusion can be nutritionally varied. The EPIC-Oxford researchers note that plant-based diets differ widely in what they contain, and that the extent of any advantage or disadvantage depends on the specific foods eaten. Trials of vegan diets also differ in whether participants are told to restrict fat, calories or portions, which affects how results are interpreted.

Relation to other Machipedia pages

This page is a member of the Machipedia family page Dietary Approaches. Related pages include Vegetarian Diet, Plant-Based Diet and Raw Food Diet, which is a distinct pattern not described here. Dietetics, the regulated health profession, and Nutritional Therapy, which has its own page, are the practice areas through which people most often receive individual dietary guidance.

Reasons people adopt the diet

The Vegan Society frames veganism chiefly as an ethical position on the use of animals. The Academy of Nutrition and Dietetics statement adds environmental reasoning, stating that plant-based diets use fewer natural resources and are associated with much less environmental damage than diets rich in animal products. The British Dietetic Association page makes a similar land, water and energy comparison for the United Kingdom.

Health claims made for the diet

The Academy of Nutrition and Dietetics states that appropriately planned vegetarian and vegan diets may provide health benefits for 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 types of cancer and obesity. These are statements about association and potential, made by a professional body, and they rest on the studies summarized in the next section.

Popular claims that go further, for example that the diet reverses an established disease, are not supported by the sources reviewed for this page. Trial authors describe improvements in measured risk factors, not outcomes such as disease remission or fewer cardiovascular events.

Randomized trials and systematic reviews

A 2021 Cochrane review of vegan dietary patterns for cardiovascular prevention included 13 randomized trials and found none reporting clinical endpoints such as heart attack or death. In people at risk, compared with no or minimal intervention, it reported moderate-certainty evidence that a vegan diet probably leads to a small reduction in total and LDL cholesterol, with no clear effect on blood pressure. Compared with other diets, it found little or no difference in LDL or HDL cholesterol.

A meta-analysis of 11 trials with 796 adults who had overweight or type 2 diabetes, lasting at least 12 weeks, reported lower body weight, BMI, glycated hemoglobin, and total and LDL cholesterol on vegan diets than on control diets, with no effect on blood pressure, HDL cholesterol or triglycerides. The authors note that some of the effect may reflect differences in macronutrient composition and energy intake, and call for more research.

Individual trials

In a 2006 trial of 99 adults with type 2 diabetes, a low-fat vegan diet was compared with a diet following American Diabetes Association guidelines over 22 weeks. Body weight and glycemic markers improved in both groups, with larger changes on the vegan diet in several measures, and a larger share of the vegan group reduced diabetes medication. Medication changes complicate interpretation, and the record lists authors affiliated with an organization that advocates plant-based diets.

A 2023 trial randomized 22 pairs of identical twins to a healthy vegan or healthy omnivorous diet for 8 weeks. It was open label, with meals delivered for the first 4 weeks. The vegan twins had lower LDL cholesterol, fasting insulin and body weight than their co-twins. The study is small and short, and it compared healthy versions of each diet, so it cannot show long-term outcomes.

Cohort studies and their limits

The Adventist Health Study-2 followed 88,400 participants for 971,424 person-years, with 12,515 deaths. Compared with non-vegetarians, vegetarians overall had lower risks of all-cause mortality and several cause-specific mortalities, and vegans were observed to have lower total mortality and several similar cause-specific mortalities. The authors also report higher neurologic mortality, specifically stroke and dementia, among older vegetarians, and state the results need further investigation.

A review of the EPIC-Oxford cohort reports that vegans had a lower risk of diabetes, diverticular disease and cataracts and a higher risk of fractures, with insufficient data for other conditions. Both cohorts classify diet by questionnaire and are observational, so differences may reflect other lifestyle factors. Vegan participants in these cohorts were relatively few and are not necessarily representative of vegans in general.

Nutrients that sources highlight

Sources agree that a vegan diet needs a reliable source of vitamin B12. The Academy of Nutrition and Dietetics states that vegans need fortified foods or supplements for it, and the British Dietetic Association page says the only reliable sources are fortified foods and supplements. The BDA page also discusses iodine, calcium, omega-3 fats and iron as nutrients to attend to, and notes that excess iodine is also harmful. This page does not give doses; a dietitian can assess individual needs.

The EPIC-Oxford review names vitamin B, vitamin D, calcium and iodine as micronutrients with a risk of low intake, particularly in vegans, and reports lower bone mineral density in vegetarians and vegans than in comparable meat eaters. In the EPIC-Oxford fracture analysis of 1,982 vegans at baseline over about 17.6 years, vegans had a higher risk of hip fracture (hazard ratio 2.31) and of total fractures (1.43) than meat eaters, with associations attenuated but still significant after adjustment for dietary calcium and protein. The authors conclude that bone health in vegans requires further research.

Life stages and professional positions

The Academy of Nutrition and Dietetics states that appropriately planned vegetarian, including vegan, diets are nutritionally adequate and appropriate at all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence and older adulthood. The British Dietetic Association similarly says carefully planned plant-based diets can support health at every age and life stage. The qualifier is planning: both statements depend on nutrient needs being met, and the sources reviewed here give no stage-specific detail beyond that.

The BDA page reviewed does not discuss pregnancy and gives no specific guidance for children, so those readers should seek individual advice from a dietitian or other qualified clinician. This page is not a substitute for care, and a vegan diet should not delay or replace necessary medical treatment.

Disordered eating

A systematic review of 48 studies found no consensus on whether vegetarian or vegan diets are associated with higher rates of disordered eating, and reported a positive association with orthorexia nervosa symptoms. Because most studies were cross-sectional, it states that causality cannot be confirmed, including whether the diet raises risk or whether disordered eating leads people to adopt it. It also found that common eating-disorder questionnaires may not measure the same thing in vegans.

For clinicians, the review suggests understanding why a person follows a vegan diet and when they began it, so that ethically motivated eating is not treated as a symptom in itself. Anyone with concerns about restrictive eating should seek help from a qualified health professional.