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Dear Dietitian – Does fish oil help depression?

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PICT Leanne McCrate Dear Dietitian
Leanne McCrate, RD, LD, CNSC

Dear Dietitian

My cousin tells me she is taking fish oil supplements to help her with depression.  Do you know of any studies on this topic?


Dear Andrea,

Omega-3 fatty acids, or simply omega-3s, have received a considerable amount of attention from the healthcare field and the general public. There are several omega-3s, and two in particular have been studied, DHA (Docosahexaenoic acid) and EPA (Eicosapentaenoic acid), which are found in fish, especially fatty fish like salmon, herring, and rainbow trout. They are found in lesser amounts in seafood. Omega-3s are also sold as fish oil supplements with an estimated 19 million Americans taking them daily. EPA and DHA are thought to have certain health benefits and have been studied for their effects on depression.

The term ‘omega-3 fatty acid’ is a chemical compound (think chemistry), which is named for the way it is structured.  Its first double bond is 3 carbons from the omega-end; its main structure is a fatty acid, hence the name omega-3 fatty acid.

In a meta-analysis published in the Journal of the College of American Nutrition, Martins found that supplementation of omega-3 fatty acids was found to improve symptoms in those with mild to moderate depression. Symptoms were better improved when patients took a supplement with greater than 50 percent EPA. It is important to note that improvement was found when fish oil supplements were taken in conjunction with medication and when treating depression instead of preventing it. Some studies showed improvement in depressive symptoms when supplementing with moderate amounts of omega-3s but not high amounts. Other studies did not show a significant effect on depression when supplementing with DHA.

Although this meta-analysis shows some promise in using omega-3s to improve depressive symptoms, problems were detected in the methods used in some of the studies, which brings into question the validity of their findings. The bottom line is more studies are needed to determine whether or not omega-3s are effective in helping depression. Clinical research is a complex task that oftentimes takes years to complete.

Good health to you!

Dear Dietitian

Disclaimer:  The information in this column is for educational purposes and is not intended to provide medical advice.  Depression is a complex medical condition that requires diagnosis and treatment by a physician.

Leanne McCrate, RD, LD, CNSC, is a dietitian based in Missouri.  Her mission is to educate the public on sound, evidence-based nutrition.  Do you have a nutrition question? Email her at