Blog | Thursday, June 6, 2013

QD: News Every Day--Clinicians need to consider what 'vegetarian' diets are, rather than their effect on longevity

Vegetarian diets are associated with lower all-cause mortality and with some reductions in cause-specific mortality, but dietary guidance should question every aspect of nutrition as well, a study and editorial concluded.

To evaluate the association between vegetarian dietary patterns and mortality, researchers conducted a prospective cohort study, controlling for demographics and lifestyle confounders, among more than 73,000 Seventh-day Adventists recruited from 2002 to 2007.

Patients were categorized into 5 dietary patterns based on responses to a questionairre: nonvegetarian, semi-vegetarian (meat less than once a week), pesco-vegetarian, lacto-ovo-vegetarian and vegan.

Results appeared online June 3 at JAMA Internal Medicine.

There were 2,570 deaths among during a mean follow-up time of 5.79 years, for an overall mortality rate of 6.05 (95% CI, 5.82-6.29) deaths per 1,000 person-years. The adjusted hazard ratio (HR) for all-cause mortality in all vegetarians combined vs. nonvegetarians was 0.88 (95% CI, 0.80-0.97). For the subgroups all-cause mortality compared to nonvegetarians was:
--vegans: HR, 0.85; 95% CI, 0.73-1.01;
--lacto-ovo-vegetarians: HR, 0.91; 95% CI, 0.82-1.00
--in pesco-vegetarians: HR, 0.81; 95% CI, 0.69-0.94; and
--semi-vegetarians: HR, 0.92; 95% CI, 0.75-1.13.

When broken down by disease mortality, there were significant associations with vegetarian diets for cardiovascular mortality, noncardiovascular noncancer mortality, renal mortality, and endocrine mortality, researchers wrote. Associations in men were larger and more often significant than were those in women, who experienced no significant reductions in these categories of mortality.

Researchers wrote, "We believe that perceived healthfulness of vegetarian diets may be a major motivation of Adventist vegetarians. More important, other large cohort studies have linked increased red and processed meat consumption to higher mortality and our findings build on this work by demonstrating reduced morality in those consuming low-meat dietary patterns."

Still, they noted, the study drew only an association between diet and mortality, and was limited to a single snapshot of diet rather than a reflection of how diets change over a lifetime.

In an editorial, a physician and former vegetarian noted these two points, and added that the label of "vegetarian" is a challenge to clinical practice. Other factors include asking questions about intake of dairy, eggs, fish and meat; assess total calories; assess intake of sugars, refined grains and trans fats; and question intake of fruits, vegetables, and nuts.

He wrote, "In short, vegetarian diets can represent a wide spectrum of nutrient intake, and it is the clinician's responsibility to help the patient determine the potential health benefits or harms of a particular diet."