A vegetarian guidebook published in Great Britain made the following claim:
You and your children don't need to eat meat to stay healthy. In fact, vegetarians claim they are among the healthiest people around, and they can expect to live nine years longer than meat eaters (this is often because heart and circulatory diseases are rarer). These days almost half the population in Britain is trying to avoid meat, according to a survey by the Food Research Association in January 1990. (77)
In commenting on this claim of extended lifespan, author Craig Fitzroy astutely points out that:
The ' nine-year advantage ' is an oft-repeated but invariably unsourced piece of anecdotal evidence for vegetarianism. But anyone who believes that by snubbing mum's Sunday roast they will be adding a decade to their years on the planet is almost certainly indulging in a bit of wishful thinking. (78)
And that is what most of the claims for increased longevity in vegetarians are: anecdotal. There is no proof that a healthy vegetarian diet when compared to a healthy omnivorous diet will result in a longer life. Additionally, people who choose a vegetarian lifestyle typically also choose not to smoke, to exercise, in short, to live a healthier lifestyle. These things also factor into one's longevity.
In the scientific literature, there are surprisingly few studies done on vegetarian longevity. Russell Smith, PhD, in his massive review study on heart disease, showed that as animal product consumption increased among some study groups, death rates actually decreased! (79) Such results were not obtained among vegetarian subjects. For example, in a study published by Burr and Sweetnam in 1982, analysis of mortality data revealed that, although vegetarians had a slightly (.11%) lower rate of heart disease than non-vegetarians, the all-cause death rate was much higher for vegetarians (80).
Despite claims that studies have shown that meat consumption increased the risk for heart disease and shortened lives, the authors of those studies actually found the opposite. For example, in a 1984 analysis of a 1978 study of vegetarian Seventh Day Adventists, HA Kahn concluded,
Although our results add some substantial facts to the diet-disease question, we recognize how remote they are from establishing, for example, that men who frequently eat meat or women who rarely eat salad are thereby shortening their lives. (81)
A similar conclusion was reached by D.A. Snowden (82). Despite these startling admissions, the studies nevertheless concluded the exact opposite and urged people to reduce animal foods from their diets.
Further, both of these studies threw out certain dietary data that clearly showed no connection between eggs, cheese, whole milk, and fat attached to meat (all high fat and cholesterol foods) and heart disease. Dr. Smith commented,
In effect the Kahn [and Snowden] study is yet another example of negative results which are massaged and misinterpreted to support the politically correct assertions that vegetarians live longer lives. (83)
It is usually claimed that meat-eating peoples have a short life span, but the Aborigines of Australia, who traditionally eat a diet rich in animal products, are known for their longevity (at least before colonization by Europeans). Within Aboriginal society, there is a special caste of the elderly (84). Obviously, if no old people existed, no such group would have existed. In his book Nutrition and Physical Degeneration, Dr. Price has numerous photographs of elderly native peoples from around the world. Explorers such as Vilhjalmur Stefansson reported great longevity among the Innuit (again, before colonization). 
Similarly, the Russians of the Caucasus mountains live to great ages on a diet of fatty pork and whole raw milk products. The Hunzas, also known for their robust health and longevity, eat substantial portions of goat's milk which has a higher saturated fat content than cow's milk (86). In contrast, the largely vegetarian Hindus of southern India have the shortest life-spans in the world, partly because of a lack of food, but also because of a distinct lack of animal protein in their diets (87). H. Leon Abrams' comments are instructive here:
Vegetarians often maintain that a diet of meat and animal fat leads to a pre-mature death. Anthropological data from primitive societies do not support such contentions. (88)
With regards to endurance and energy levels, Dr Price traveled around the world in the 1920s and 1930s, investigating native diets. Without exception, he found a strong correlation between diets rich in animal fats, robust health and athletic ability. Special foods for Swiss athletes, for example, included bowls of fresh, raw cream. In Africa, Dr Price discovered that groups whose diets were rich in fatty meats and fish, and organ meats like liver, consistently carried off the prizes in athletic contests, and that meat-eating tribes always dominated tribes whose diets were largely vegetarian. (89)
It is popular in sports nutrition to recommend "carb loading" for athletes to increase their endurance levels. But recent studies done in New York and South Africa show that the opposite is true: athletes who "carb loaded" had significantly less endurance than those who "fat loaded" before athletic events (90).
B McConville. The Parents' Green Guide. (London: Pandora), 1990.
C Fitzroy. The Great Fallacies of Vegetarianism. Accessed on December 27, 2001.
R Smith and E Pinckney. Diet, Blood Cholesterol, and Coronary Heart Disease: A Critical Review of the Literature--vol. 2. (Vector Enterprises; CA)., 1991. A shortened adaptation of Smith's section on vegetarianism and longevity was published in Jnl of PPNF, 1998, 22:4: 27-29. See also S Fallon and M Enig. Wise Choices, Healthy Bodies. Wise Traditions, 2000, Winter, 15-21.
ML Burr and PM Sweetnam. Vegetarianism, dietary fiber, and mortality. Amer J Clin Nutr, 1982, 36:873.
HA Kahn and others. Association between reported diet and all-cause mortality. Amer J Epidem, 1984, 119:775.
DA Snowden and others. Meat consumption and fatal ischemic heart disease. Prev Med, 1984, 13:490.
R Smith and E Pinckney. Diet, Blood Cholesterol, and Coronary Heart Disease: A Critical Review of the Literature--vol. 2.
WA Price. Nutrition and Physical Degeneration, 163-187.
V. Stefansson. The Fat of the Land, (Macmillan; NY), 1956.
(a) G.Z. Pitskhelauri. The Long Living of Soviet Georgia. (Human Sciences Press; NY), 1982; (b) Thomas Moore. Lifespan: What Really Affects Human Longevity (Simon & Schuster; NY), 1990.
HL Abrams. The relevance of paleolithic diet in determining contemporary nutritional needs. J Appl Nutr, 1979, 31:1,2:43-59.
HL Abrams. Vegetarianism: An anthropological/nutritional evaluation. J Appl Nutr, 1980, 32:2:53-87.
WA Price. Nutrition and Physical Degeneration, 23-44, 129-163.
J Raloff. High Fat Diets Help Athletes Perform. Science News, 1996, 149:18:287.