Meta-analysis Reassesses Omega 3 Fatty Acids in Major Depressive Disorders Interview with:

Dr. Roel JT Mocking Program for Mood Disorders Department of Psychiatry Academic Medical Center University of Amsterdam, The Netherlands

Dr. RJT Mocking

Dr. Roel JT Mocking
Program for Mood Disorders
Department of Psychiatry
Academic Medical Center
University of Amsterdam, The Netherlands What is the background for this study?

Response: Omega-3 polyunsaturated fatty acid supplementation (popularly referred to as fish oil) is being promoted as (add-on) treatment for depression. Thus far, many studies have been performed that tested the effects of omega-3 fatty acids in depression. In order to overcome differences between these results of individual studies, a meta-analysis can be performed. A meta-analysis pools the results of all individual studies, and thereby provides a more definitive conclusion regarding the effect of omega-3 fatty acids in depression. Moreover, using the differences between the individual studies, a meta-analysis can point to factors that are associated with a better effect of the supplementation, for example supplementation dose or duration.

There have been meta-analyses performed previously, but they seemed to contain several inconsistencies. For example, they accidentally included the same study two or three times, which results in errors. In addition, these meta-analyses did not only include studies performed in patients with the psychiatric disorder “major depressive episode”, but also subjects from the general population with less severe depressive complaints. This makes it more difficult to interpret the results. Therefore, we performed a meta-analysis that included only studies performed in patients with major depressive disorder, and corrected errors from earlier meta-analyses. What are the main findings?

Response: We found that overall, omega-3 fatty acid supplementation was effective in depression. The effect-size of supplementation was comparable to the effect-size reported in meta-analyses on antidepressant medication. Interestingly, in our meta-analysis, effects differed substantially between the individual studies. We observed that supplementation was specifically effective in studies supplementing higher doses of the omega-3 fatty acid eicosapentaenoic acid (EPA), in patients also taking antidepressant medication. Studies supplementing the omega-3 fatty acid docosahexaenoic acid (DHA), and those performed in patients not using antidepressants, were less effective. What should clinicians and patients take away from your report?

Response: Our results suggest that not all omega-3 fatty acids are equal. The omega-3 fatty acid eicosapentaenoic acid (EPA) seems to have a beneficial effect in patients with major depressive disorder taking antidepressants. It may be recommendable for patients and clinicians to consider EPA supplementation in major depressive disorder as an add-on treatment next to antidepressants. Our results do not recommend taking supplements against depression with only the omega-3 fatty acid DHA, or using omega-3 fatty acids supplements for less severe depressive complaints. What recommendations do you have for future research as a result of this study?

Response: Based on our results, it would be advisable for future research to specifically focus on EPA supplementation instead of DHA supplementation. This may lead to better outcomes in studies, and thereby more conclusive advice for the clinic that can be implemented in guidelines to help the large number of patients suffering from depression worldwide. In addition, it would be interesting to test the observed interaction between EPA and antidepressants. If we would better understand which supplements are effective in what persons, we may come up with a more personalized treatment plan. Is there anything else you would like to add?

Response: Supplementation, including omega-3 fatty acids, may also have adverse effects. It seems therefore advisable to make sure you get all your nutrients from a balanced and healthy diet, including 2 servings of fish (of which 1 fatty fish) a week. Thank you for your contribution to the community.


Transl Psychiatry. 2016 Mar 15;6:e756. doi: 10.1038/tp.2016.29.

Meta-analysis and meta-regression of omega-3 polyunsaturated fatty acid supplementation for major depressive disorder.

Mocking RJ1, Harmsen I1, Assies J1, Koeter MW1, Ruhé HG1,2, Schene AH3,4.

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Dr. R.J.T Mocking (2016). Meta-analysis Reassess Omega 3 Fatty Acids in Major Depressive Disorders