This is a difficult question to answer accurately, as there are few studies on lifelong vegetarians in countries with electricity, refrigeration, good sanitation, and adequate nutrition. American studies done in 1984 on Seventh-Day Adventists, a religious group that provides dietary and lifestyle advice to its members, sheds some light on this issue. Adventist leadership discourages the consumption of meat, fowl, and eggs; pork is prohibited. Because eating animal products is only discouraged and not necessarily prohibited, there is a large range in animal-product consumption. Some Adventists never eat meat and eggs, whereas others consume them daily. When we take a careful look at the Seventh-Day Adventist data, those who lived the longest were those following the vegetarian diet the longest, and when we look at the subset who had followed a vegetarian diet for at least half their life, it appears they lived about thirteen years longer than their average, non-smoking Californian counterparts.1 Most of the participants in this study were converted to the religion, not born into it. There was no data on those following such a diet since childhood. However, the data from this carefully constructed study was compelling; and what is of considerable interest to me is the association of green salad consumption and longer life.2 Leafy greens, the most nutrient-rich foods on the planet, were the best predictor of extreme longevity.
Some nutritional experts would argue that a strict vegetarian who follows a diet rich in natural vegetation, not refined grains, has the longest longevity potential, as indicated by evaluating the China Project data together with hundreds of the smaller food-consumption studies—but, of course, this is still educated speculation. Let’s not argue whether it is all right to eat a little bit of animal foods or not, and thereby miss the point that cannot be contradicted or disagreed with:
Whether you eat a vegetarian diet or include a small amount of animal foods, for optimal health you must receive the majority of your calories from unrefined plant food. It is the large quantity of unrefined plant food that grants the greatest protection against developing serious disease.
1. Ruckner C., and J. Hoffman. 1991. The Seventh-Day Adventist diet. New York: Random House, 1991.
2. Kahn, op. cit., pp. 775–79.