Does a Poor Diet Cause Depression

Today’s blog post is going to focus on the relationship between food and mood. More specifically does a diet filled with junk food actually cause depression? First off, it would be easy for me to make a snap judgement and say “of course it does”. My life, after all, revolves around helping people make healthy changes to their diet and lose weight naturally. Instead of just assuming that a poor diet causes any number of health conditions I prefer to look at the data and interpret it.

My simple answer to the question of “does a poor diet cause weight loss?” is NO. As shocking as this revelation may be I believe, based on what I have read, that there is likely another factor that causes both a poor diet and depression. So let’s look at the research.

One popular study on the link between diet and mood found that: “A dietary pattern characterized by a high intake of fruit, vegetables, whole grain, fish, olive oil, low-fat dairy and antioxidants and low intakes of animal foods was apparently associated with a decreased risk of depression. A dietary pattern characterized by a high consumption of red and/or processed meat, refined grains, sweets, high-fat dairy products, butter, potatoes and high-fat gravy, and low intakes of fruits and vegetables is associated with an increased risk of depression.” This sounds like a slam-dunk right. Diet obviously effects mood and can lead to depression.

We can’t stop here however. What if the people in the study were depressed and then turned to easy junk foods for comfort. Luckily researchers wondered this as well and in another large analysis they looked at baseline diet and then calculated the risk of participants later developing depression. They found that “A healthy diet (the Mediterranean diet as an example) was associated with a significantly lower risk of developing depressive symptoms.” So that should put a bow on it. Diet directly effects mood. But wait, earlier I said that I don’t think this is the case. So why am I quoting all this research stating that food does effect mood. The reason is that I still don’t think that the research has dived deep enough to really uncover the source of the depression.

Correlation does not mean causation. Just because two factors happen together does not mean that one causes another. So what could cause both a poor diet and depression? The research is pretty clear on this. Income-inequality, more specifically, having a very low income compared to the general society can contribute directly to a depressive state. People with a lower income are also much more likely to choose cheap, fat and generally unhealthy food.

In conclusion, I believe that maintaining a healthy diet can be beneficial in countless ways. It may even make you feel a little better emotionally. I don’t however believe that diets directly cause depression. Depression and poor diet can be seen to be more easily caused by having a low income.