Outside of the air we breathe, food is the biggest input into our bodies. So it makes sense that what we put in our mouths affects not just our physical health, but our mental health as well. But what diet is best for psychological well-being?
In this week's news, there is a lot of coverage of the Mediterranean diet and its link to less depression:
The Guardian: Eating junk food raises risk of depression, says multi country study BBC News: Mediterranean diet 'may help prevent depression Irish Times: Mediterranean diet may help cut depression risk by a third CNN News: Mediterranean diet could prevent depression, new study findsA new review, published in Molecular Psychology, analyzed 41 observational studies, and found that subjects eating a Mediterranean-style diet experienced lower rates of depression. The study also found that those eating other diets, characterized as either anti-inflammatory by the Dietary Inflammation Index (DII) or conforming with the Healthy Eating Index (HEI), were also found to be associated with lower rates of depression. Notably, the low-fat DASH diet was not clearly associated to less depression.
What do these diets associated with less depression have in common? Real food. There was quite a bit of variety, even among each diet category, on exactly how the quality of subjects' diets was assessed. But overall, the Mediterranean, anti-inflammatory, and Healthy Eating Index definitions reward diets rich in vegetables, fruit, nuts, legumes and fish, and penalize diets high in processed red meat, sugar-sweetened beverages and fruit juice, and alcohol. In general, this study suggests that avoiding most ultraprocessed food and selecting real food is associated with less depression.
The study authors caution that this is observational data and does not prove that the healthier real food diets actually cause less depression. Although we find this relationship plausible, clinical trials are required to prove a causal relationship.
What about low-carb diets? They are real food diets. Might they, although they often contain more meat and dairy than Mediterranean diets, nonetheless be linked to less depression? Unfortunately, there is no clinical trial evidence looking at this question. But several doctors think so. Watch our composite interview with doctors Fung, Brukner, Hallberg and Chatterjee, where they report that they see patient mood improve when they switch to a low-carb lifestyle.
While we await more clinical trials targeted at the links between diet and mental health, avoiding processed food and eating whole foods seems like a wise strategy.
Molecular Psychology: Healthy dietary indices and risk of depressive outcomes: a systematic review and meta-analysis of observational studies