Extensive research into the nutritional adequacy of vegetarian diets has shown that a well-planned vegetarian or vegan diet can supply all of the nutrients required for good health. But less is known about the long-term health of vegetarians and vegans.
In a recent review paper published in the Proceedings of the Nutrition Society*, Paul Appleby and Timothy Key of the Oxford University Cancer Epidemiology Unit summarise the main findings from several large population studies in western countries with a high proportion of vegetarian participants.
The findings show that vegetarians have a lower prevalence of overweight and obesity and a lower risk of ischaemic heart disease (mainly heart attacks and angina) compared with non-vegetarians from a similar background. For cancer, there is some evidence that the risk for all cancer sites combined is slightly lower in vegetarians than in non-vegetarians. But findings for individual cancer sites are inconclusive. Vegetarians have also been found to have lower risks for diabetes, diverticular disease and eye cataract, but the data are equivocal for stroke.
Overall death rates are similar for vegetarians and comparable non-vegetarians, but vegetarian groups compare favourably with the general population. In summary, the long-term health of vegetarians appears to be generally good, and for some diseases and medical conditions it may be better than that of comparable omnivores.
Although more research is needed, particularly on the long-term health of vegans, the findings are enough to suggest that a reduction in the consumption of animal products, especially red and processed meats and high-fat dairy products, in developed and middle-income countries is likely to have a beneficial effect on public health. It would also go some way towards addressing concerns over the environmental and economic consequences of a diet rich in meat and other animal foods.
Although I have been prevented by outward circumstances from observing a strictly vegetarian diet, I have long been an adherent to the cause in principle. Besides agreeing with the aims of vegetarianism for aesthetic and moral reasons, it is my view that a vegetarian manner of living by its purely physical effect on the human temperament would most beneficially influence the lot of mankind.
* Appleby PN & Key TJ (2015) The long-term health of vegetarians and vegans.
Proceedings of the Nutrition Society; doi:10.1017/S0029665115004334. (Currently available online at http://journals.cambridge.org/ns/feb16.)