Health effects of Vegetarian and Vegan Food Pyramid
Difference between Vegetarian and Vegan Diets
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 non- Western 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 B12 and Zn.
Vegans may have particularly low intakes of vitamin B12 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 B12. Overall, the data suggest that the health of Western vegetarians is good and similar to that of comparable on-vegetarians.
Vegetarian and Vegan Health Mortality
A large number of individuals around the world follow vegetarian diets, but in most countries vegetarians comprise only a small proportion of the population. India is a notable exception because a substantial proportion of the population, perhaps approximately 35%, follows a traditional vegetarian diet and has done so for many generations.
The numbers of vegetarians in Western countries are unknown, with estimates based on rather small samples; for example, in a survey of 2251 individuals throughout the UK (Henderson et al. 2002) 5% reported being vegetarian or vegan. While the number of vegetarians may be increasing in some of the most affluent countries, there is an opposite picture for other countries around the world, in that meat consumption is increasing greatly in many countries that until recently had a low intake of meat.
Per capita meat consumption (kg/year) is predicted to increase from 24.2 in 1964–6 to 45.3 in 2030, with a very large increase in East Asia from only 8.7 in 1964–6 to 58.5 in 2030. Steinfeld (2004) has estimated that world total meat production (·106 tonnes/year) increased from about 92 in 1967–9 to 218 in 1997–9 and will increase further to 376 in 2030, a fourfold increase in 60 years. Understanding of the health effects of vegetarian and vegan diets is quite good but many uncertainties remain. The purpose of the present brief overview is to summarize current knowledge on the health effects of vegetarian and vegan diets with an emphasis on recent findings and results from large studies, including the work of the authors’ group on the European Prospective Investigation of Cancer and Nutrition. Most of the discussion is related to vegetarians in affluent Western countries; the health of vegetarians and individuals with a very low meat intake in poorer countries is a very important topic and there is some information available, but proper consideration of this topic is outside the scope of the present brief overview.
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