There’s been a lot of talk about how “traditional” diets (i.e., what your grandmother served for dinner) are better for you. I’ve generally taken issue with this precept; I wanted to believe it was true, but where’s the science supporting it?

Authors F. N. Jacka, J.A. Pasco, A. Mykletun, L.J. Williams, A.M. Hodge, S.L. O’Reilly, G.C. Nicholson, M.A. Kotowicz, M. Berk
Institution Department of Clinical and Biomedical Sciences, University of Melbourne, Geelong 3220, Australia
Publication Name The American Journal of Psychology
Publication Date March 2010

Objective
Key biological factors that influence the development of depression are modified by diet. This study examined the extent to which the high-prevalence mental disorders are related to habitual diet in 1,046 women ages 20-93 years randomly selected from the population.
Method
A diet quality score was derived from answers to a food frequency questionnaire, and a factor analysis identified habitual dietary patterns. The 12-item General Health Questionnaire (GHQ-12) was used to measure psychological symptoms, and a structured clinical interview was used to assess current depressive and anxiety disorders.
Results
After adjustments for age, socioeconomic status, education, and health behaviors, a “traditional” dietary pattern characterized by vegetables, fruit, meat, fish, and whole grains was associated with lower odds for major depression or dysthymia and for anxiety disorders. A “western” diet of processed or fried foods, refined grains, sugary products, and beer was associated with a higher GHQ-12 score. There was also an inverse association between diet quality score and GHQ-12 score that was not confounded by age, socioeconomic status, education, or other health behaviors.
Conclusions
These results demonstrate an association between habitual diet quality and the high-prevalence mental disorders, although reverse causality and confounding cannot be ruled out as explanations. Further prospective studies are warranted.