Diet quality and depression risk in a Japanese population: the Japan Public Health Center (JPHC)-based Prospective Study

The association of overall diet quality based on the Japanese Food Guide Spinning Top with risk of depression is not known. This prospective cohort study aimed to determine whether higher adherence to the Japanese food guide reduced the risk of depression. Of 12,219 residents enrolled at baseline, we extracted 1,112 participants who completed a 5-year follow-up (1995) and participated in a mental health screening (2014–2015). Diet quality was scored based on adherence to the Japanese food guide and the ratio of white to red meat according to the Alternative Healthy Index and ranged from 0 (worst) to 80 (best). We calculated odds ratios and 95% confidence intervals for current psychiatrist-diagnosed depression per quartile of total score and of eight component scores with the lowest quartile as reference. Mean age of the participants was 73 years and 59% were women. Total diet quality score was not significantly associated with risk of depression 20 years after the baseline assessment. Among the eight components on the diet quality score, there was a significantly reduced risk for the highest quartile of the white to red meat ratio score. In conclusion, our results do not indicate that higher adherence to the Japanese food guide prevents depression.