Does low meat consumption increase life expectancy in humans?

BACKGROUND: Since meat products represent a major source of protein in the Western diet, findings on whether meat intake significantly contributes to the burden of fatal disease have important clinical and public health implications.
OBJECTIVE: The objective was to examine whether a very low meat intake (less than weekly) contributes to greater longevity.
DESIGN: We reviewed data from 6 prospective cohort studies and report new findings on the life expectancy of long-term vegetarians from the Adventist Health Study.
RESULTS: Our review of the 6 studies found the following trends: 1) a very low meat intake was associated with a significant decrease in risk of death in 4 studies, a nonsignificant decrease in risk of death in the fifth study, and virtually no association in the sixth study; 2) 2 of the studies in which a low meat intake significantly decreased mortality risk also indicated that a longer duration (>/= 2 decades) of adherence to this diet contributed to a significant decrease in mortality risk and a significant 3.6-y (95% CI: 1.4, 5.8 y) increase in life expectancy; and 3) the protective effect of a very low meat intake seems to attenuate after the ninth decade. Some of the variation in the survival advantage in vegetarians may have been due to marked differences between studies in adjustment for confounders, the definition of vegetarian, measurement error, age distribution, the healthy volunteer effect, and intake of specific plant foods by the vegetarians.
CONCLUSION: Current prospective cohort data from adults in North America and Europe raise the possibility that a lifestyle pattern that includes a very low meat intake is associated with greater longevity.