Vegetarian diets have been eaten by some ethnic and religious groups for centuries for ethical reasons, and millions of people throughout the world cannot afford to eat meat. More recently, vegetarianism has been advocated as a diet that can potentially reduce the risk of chronic diseases while providing recommended nutrient intakes. So are vegetarian diets that large numbers of people adhere to particularly beneficial in their effects on health?

In 1954 it was reported that cholesterol concentrations were lower in vegetarians than in meat eaters,1 a finding repeatedly confirmed and refined to show that vegans have appreciably lower concentrations of total cholesterol and low density lipoprotein cholesterol than vegetarians.2 Vegans—who exclude eggs, milk, and dairy products in addition to not eating meat and fish—have lower intakes of saturated fatty acids than do vegetarians.

An analysis of five prospective studies indicated that mortality from ischaemic heart disease was 24% (95% confidence interval 6% to 38%) lower in vegetarians than in meat eaters,3 confirming earlier observations from a prospective follow-up of Seventh Day Adventists. A similar but non-significant difference of 19% has been reported …