The possible relationship between diet and mortality is an important area of study. Vegetarian diets have been associated with reductions in risk for several chronic diseases, including hypertension, metabolic syndrome, diabetes mellitus and ischemic heart disease (IHD), according to the study background.

Michael J. Orlich, M.D., of Loma Linda University in California, and colleagues examined all-cause and cause-specific mortality in a group of 73,308 men and women Seventh-day Adventists. Researchers assessed dietary patients using a questionnaire that categorized study participants into five groups: nonvegetarian, semi-vegetarian, pesco-vegetarian (includes seafood), lacto-ovo-vegetarian (includes dairy and egg products) and vegan (excludes all animal products).

The study notes that vegetarian groups tended to be older, more highly educated and more likely to be married, to drink less alcohol, to smoke less, to exercise more and to be thinner.

"Some evidence suggests vegetarian dietary patterns may be associated with reduced mortality, but the relationship is not well established," the study notes.

There were 2,570 deaths among the study participants during a mean (average) follow-up time of almost six years. The overall mortality rate was six deaths per 1,000 person years. The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs. nonvegetarians was 0.88, or 12 percent lower, according to the study results. The association also appears to be better for men with significant reduction in cardiovascular disease mortality and IHD death in vegetarians vs. nonvegetarians. In women, there were no significant reductions in these categories of mortality, the results indicate.

"These results demonstrate an overall association of vegetarian dietary patterns with lower mortality compared with the nonvegetarian dietary pattern. They also demonstrate some associations with lower mortality of the pesco-vegetarian, vegan and lacto-ovo-vegetarian diets specifically compared with the nonvegetarian diet," the authors conclude.