Health effects of vegetarian and vegan diets

Abstract

Vegetarian diets do not contain meat, poultry or fish; vegan diets further exclude dairy products and eggs. Vegetarian and vegan diets can vary widely, but the empirical evidence largely relates to the nutritional content and health effects of the average diet of well-educated vegetarians living in Western countries, together with some information on vegetarians in nonWestern countries. In general, vegetarian diets provide relatively large amounts of cereals, pulses, nuts, fruits and vegetables. In terms of nutrients, vegetarian diets are usually rich in carbohydrates, n-6 fatty acids, dietary fibre, carotenoids, folic acid, vitamin C, vitamin E and Mg, and relatively low in protein, saturated fat, long-chain n-3 fatty acids, retinol, vitamin B 12 and Zn; vegans may have particularly low intakes of vitamin B 12 and low intakes of Ca. Crosssectional studies of vegetarians and vegans have shown that on average they have a relatively low BMI and a low plasma cholesterol concentration; recent studies have also shown higher plasma homocysteine concentrations than in non-vegetarians. Cohort studies of vegetarians have shown a moderate reduction in mortality from IHD but little difference in other major causes of death or all-cause mortality in comparison with health-conscious non-vegetarians from the same population. Studies of cancer have not shown clear differences in cancer rates between vegetarians and non-vegetarians. More data are needed, particularly on the health of vegans and on the possible impacts on health of low intakes of long-chain n-3 fatty acids and vitamin B 12 . Overall, the data suggest that the health of Western vegetarians is good and similar to that of comparable non-vegetarians.

Influence of habitual diet on antioxidant status: a study in a population of vegetarians and omnivores

“…This might in part be due to the higher intake of antioxidant nutrients and extra-nutrients in vegetarians (Sabate, 2003;Cade et al, 2004;Key et al, 2006). However, very few studies looked at antioxidant status in vegetarians as compared with omnivores (Krajcovicova- Kudlackova and Dusinska, 2004;Szeto et al, 2004).…”

Age-Related Alterations of B-Group Vitamin Contents in Urine, Blood and Liver from Rats

“…Urinary excretion of B-group vitamins was periodically measured from 14 to 80 wk old, and blood and liver B-group vitamin levels in aged rats were compared with those in young rats. As for vitamin B 6 and folic acid, the blood and liver contents in aged rats were much lower than those in young rats, while aging did not affect their urinary excretion. Plasma vitamin B 12 in aged rats was also lower than that in young rats.…”

Health, ethics and environment: A qualitative study of vegetarian motivations

“…Personal health and animal cruelty figure high on this list (Hoek et al 2004, 266, Lea andWorsley 2001, 127), while disgust or repugnance with eating flesh (Kenyon and Barker 1998, Rozin et al 1997, Santos and Booth 1996, association with patriarchy (Adams 1990), food beliefs and peer or family influences (Lea and Worsley 2001, 128) are also noted. Health vegetarians choose to avoid meat in order to derive certain health benefits or lose weight (Key et al 2006, Kim and Houser 1999, Wilson et al 2004, while ethical vegetarians consider meat avoidance as a moral imperative not to harm animals for food or other reasons (Fessler et al 2003, 31, Whorton 1994.…”