There’s growing evidence that diet can affect the risk of developing depression. Although previous studies that looked at the effect of single nutrients have come to different conclusions, a new review of existing research suggests that, taken as a whole, people with more healthful diets have a lower risk of depression.
The review, published in the American Journal of Clinical Nutrition, looked at 21 studies. Reviews like this, known as a meta-analysis, can be useful in getting the bigger picture on a topic.
In this review, two main dietary patterns were identified: a healthful pattern and what the researchers called the Western pattern. The healthful pattern was characterised by a high intake of fruits, vegetables, whole grains and fish, while the Western pattern was characterised by high intake of refined grains, processed meats, high sugar and high fat products.
Comparing highest to lowest adherence to these patterns, researchers found that adherence to the healthful diet was associated with a significant 16 per cent lower risk of depression. There was a nonsignificant trend toward a higher risk of depression associated with the Western diet, but this non-significant finding may be due to lack of high-quality studies on this dietary pattern.
There are several ways a healthful diet could reduce the risk of depression: anti-inflammatory properties influence concentrations of monoamines; antioxidants reduce damage to neurons; omega-3 fatty acids have been associated with lower depression; or the reduced risk could be due to the cumulative effect of all these components.
What’s unclear from the review is which came first, a healthful diet or a lower risk of depression. That is, did eating well improve people’s mental health, or did people with better mental health find it easier to make good food choices? Either way, you’re certainly not going to feel worse by regularly eating a diet high in produce and whole grains.