Depression – a mood disorder that affects 322 million people worldwide – is characterized by profound sadness, anxiety, and physical complaints. People who have depression often have higher levels of systemic inflammation (which can affect brain health) compared to those without depression. Findings from a new study suggest that omega-3 fatty acids reduce symptoms of depression through their anti-inflammatory effects on the brain.

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are omega-3 fatty acids derived primarily from fish. They exert a wide range of beneficial effects on the human body. Evidence from a clinical trial indicates that omega-3 fatty acids reduce symptoms of depression associated with inflammation.

Chronic inflammation plays key roles in the development of many diseases, including cancer, cardiovascular disease, and diabetes. Inflammation in the brain impairs neurogenesis, the process of forming new neurons. Impaired neurogenesis negatively influences mood and cognitive function.

The authors of the study conducted two experiments. In the first experiment, they pre-treated human hippocampal cells with either EPA or DHA and then exposed the cells to interleukin (IL)-1 beta, IL-6, and interferon-alpha – proteins that drive chronic inflammation. They found that EPA and DHA maintained neurogenesis and prevented programmed cell death via the effects of lipid mediators – a class of omega-3 fatty acid byproducts that influence immune health and inflammation.

In the second experiment, the authors gave 22 people who had been diagnosed with depression either 3 grams of EPA or 1.4 grams of DHA for 12 weeks. They measured lipid mediators in the participants' blood and assessed their depression symptoms. The authors found that the anti-inflammatory lipid mediators increased in the participants' blood. They also noted that the participants' depressive symptoms decreased approximately 64 percent with EPA and 71 percent with DHA.

These findings suggest that omega-3 fatty acids reduce the inflammation associated with depression and improve depressive symptoms. This was a very small study, however, and did not include a control group. Further research is needed to confirm these findings. Learn more about the role of inflammation in depression in this clip featuring Dr. Charles Raison.

• Link to full study.

• For a quick and tasty way to get more omega-3 fatty acids into your diet, check out this recipe video featuring Dr. Rhonda Patrick.