Break out the broccoli: junk food and depression

The study published in the British Journal of Psychiatry found that people with the highest intake of "whole foods" - fruit, veg etc - were less likely to report suffering from depression.

The authors said: "Our results suggest that consuming fruits, vegetables and fish may afford protection against the onset of depressive symptoms, whereas a diet rich in processed meat, chocolates, sweetened desserts, fried food, refined cereals and high-fat dairy products would increase people's vulnerability."

Fighting Monsters points out that a poor diet may also correlate with lower income, another potential factor in mental health. However, the researchers, from University College London appear to tackle this:

Second, some bias owing to selective retention of participants is possible as we found socioeconomic position, depression and dietary patterns to be associated with the likelihood of being included in the analyses. If anything, this could contribute to an overestimation of the association between a whole food pattern and self-reported depression on account of the overrepresentation of individuals without depression who follow a health-conscious diet.

Also, is there any weight in the argument that depressed people are less likely to make the effort to cook fresh food?

The researchers also appear to tackle this issue:

First, reverse causation - with depression affecting the dietary pattern rather than the other way around - remains an alternative interpretation of the observed associations. To test this issue, we undertook sensitivity analyses and found no significant association between previous reports of depression (phase 3, 1991-3) using the GHQ depression subscale and dietary patterns assessed 6 years later. This suggests that depression did not predict dietary behaviour in our study.

It seems a pretty strong survey to me (although I'm not an expert in research methodology) but in any case adopting a healthy diet is pretty much a risk free strategy. Break out the broccoli.