We know that people who are depressed don’t eat as well as people who don’t have depression. So not surprising to anyone, diet and what we eat remain linked to depression. But despite new research, we still don’t know which way the relationship goes — does diet cause depression, or do people with a certain lifestyle or with depression eat poor diets?

They split the participants into two types of diet – those who ate a diet largely based on whole foods, which includes lots of fruit, vegetables and fish, and those who ate a mainly processed food diet, such as sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products.

After accounting for factors such as gender, age, education, physical activity, smoking habits and chronic diseases, they found a significant difference in future depression risk with the different diets.

Those who ate the most whole foods had a 26% lower risk of future depression than those who at the least whole foods.

By contrast people with a diet high in processed food had a 58% higher risk of depression than those who ate very few processed foods.

There are three reasonable explanations for this finding. The one the researchers believe is that what you eat can directly impact your mood over the long run. Another explanation is that people who are more prone to depression live a kind of lifestyle where eating processed food is a normal part of it (think of a person who is harried and stressed out and doesn’t know how to manage stressors in their life very well). “Physical activity” and education don’t really rule out the possibility of the second explanation.

And the third explanation is that people with depression eat less healthily. That also seems like a reasonable explanation for this finding. The news article doesn’t say whether they assessed depression at the onset of the study (which seems like a pretty reasonable thing to have done).

Honestly, I’m not sure eating more healthy is going to directly impact your mood. It will, however, impact your overall general health, which does have an impact on your mood. So even if it’s not a direct relationship, it’s something to think about next time you find yourself stopping into McDonald’s for the 5th time this month (or week!).

Read the full article: Depression link to processed food

Dr. John Grohol is the CEO and founder of Psych Central. He is an author, researcher and expert in mental health online, and has been writing about online behavior, mental health and psychology issues -- as well as the intersection of technology and human behavior -- since 1992. Dr. Grohol sits on the editorial board of the journal Cyberpsychology, Behavior and Social Networking and is a founding board member and treasurer of the Society for Participatory Medicine.

    Last reviewed: By John M. Grohol, Psy.D. on 2 Nov 2009
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