Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2

Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2, led by Michael J. Orlich, Pramil N. Singh, Joan Sabate, Gary E. Fraser and colleagues and published in JAMA Internal Medicine in 2013, presents the principal mortality result from the large, ongoing prospective cohort study of Seventh-day Adventists in North America, finding lower all-cause mortality among vegetarian dietary patterns compared with non-vegetarian ones within the cohort. Its strength is a large sample size and rigorous peer reviewed epidemiological design within a population whose religiously motivated dietary practice makes it an unusually good natural cohort for studying diet's health effects. Its limit is that it is an observational cohort study, not a randomized trial, so it can show association rather than prove that diet alone caused the mortality difference; other lifestyle factors correlated with Adventist practice could contribute, a limitation the study's own authors discuss.