Vegetarian diet may predispose to depression

Individuals following a vegetarian diet are at increased risk of depression, a recent study suggests.

The study was based on a meta-analysis of observational studies investigating mean levels of depression and risk for depression in vegetarians compared with nonvegetarians.

Estimated using the random-effects model, pooled data revealed that adherence to a vegetarian diet conferred a 53-percent increase in the risk of depression compared with omnivore diets (odds ratio [OR], 1.53, 95 percent confidence interval [CI], 1.14–2.07; I², 69.1 percent).

In a subgroup analysis, the association between vegetarian diet and depression differed by the type of diet and country where the study was conducted. Specifically, the association was evident for a semivegetarian diet (OR, 1.86, 95 percent CI, 1.42–2.44; I², 35.7 percent) and in studies conducted in Europe and the United States (OR, 1.45, 95 percent CI, 1.06–1.98; I², 73.2 percent).

On the other hand, there was a null association for lacto-ovo vegetarians and in studies conducted in Asian countries.

When comparing mean depression scores, there was no evidence of difference between vegetarians and nonvegetarians (n=16; standardized mean difference, 0.10, 95 percent CI, –0.01 to 0.21; I², 79.1 percent).

Overall, the findings were not robust. Therefore, additional studies are needed to establish the association between vegetarian diet and depression risk.