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What is it?

Omega-3 is a type of polyunsaturated fatty acid. Omega-3 fatty acids are important for overall health and wellbeing.

There are different types of omega-3 fatty acids. These are:

  • alpha-linolenic acid (ALA);
  • eicosapentaenoic acid (EPA); and
  • docosahexaenoic acid (DHA).

ALA is found mostly in walnuts, some seeds, and some oils. EPA and DHA are found in oily fish and eggs. ALA is converted into EPA and DHA by the body.

How does it work?

Omega-3 and depression have been linked in the following ways.

  • Some people with depression have lower levels of omega-3 in their red blood cells. This has led to the belief that low levels of omega-3 are linked with depression.
  • Some people believe depression is caused by inflammation. Omega-3 may reduce inflammation.
  • Countries with high fish consumption have lower reported rates of depression.

Is it effective?

There have been a number of studies which have looked at the effectiveness of omega-3 for treating depressiond.

Some analyses of studies which look at omega-3 have found that it is effective in reducing symptoms of depression compared to a control. However, a recent analysis of studies of omega-3 as a treatment for depression in adults found that the available evidence is not of high quality and that benefits are likely to be small and not of clinical value. Another large umbrella review of other reviews also found limited evidence of low quality.

Some reviews have found evidence that omega-3 is particularly effective for people who are also taking antidepressants. However, a recent review of a small number of studies which looked at adding omega-3 to anti-depressants did not find evidence that omega-3 helped to reduce depression symptoms in people who are also taking antidepressant medication.

There is some research on the different types of fatty acids. One analysis of data from other studies found that supplements containing mostly EPA-type omega-3 were effective at reducing depression symptoms. However the included studies had wide variation in how this was tested. 

More large studies of high quality are needed to better understand the effectiveness of omega-3 for depression.

Are there any disadvantages?

There are some reported side effects of fish-oil tablets, including bloating, gas, belching, nausea, bad breath and/or loose stools.

Some supplements can be harmful or ineffective if you take the wrong dose. Talk to your health care professional if you are thinking of taking supplements, including omega-3.

Where do you get it?

Many foods are high in omega-3 fatty acids. These include oily fish (such as salmon, mackerel, and sardines), eggs, walnuts, some seeds (including hemp and flaxseed), and some oils.

Omega-3 supplements are available at supermarkets, health food shops and pharmacies.

Fish oil supplements may also contain omega-3 fatty acids but the amount will vary. It is important to check the label to see if the supplement contains omega-3.


There some is evidence to suggest omega-3 helps depression, but more studies of better quality are needed.

Key references

  • Accinni T, Panfili M, Tarsitani L, Biondi M, Pasquini M, Maraone A. A Revision on the Effectiveness of Omega-3 Polyunsaturated Fatty Acids as Monotherapy in the Treatment of Major Depressive Disorder. International Journal of Clinical Practice. 2022; 2022:3801235-10.
  • Appleton KM, Appleton KM, Voyias PD, Sallis HM, Dawson S, Ness AR, et al. Omega‐3 fatty acids for depression in adults. Cochrane Database of Systematic Reviews. 2021; 2021(11):CD004692-CD.
  • Chambergo-Michilot D, Brañez-Condorena A, Falvy-Bockos I, Pacheco-Mendoza J, Benites-Zapata VA. Efficacy of omega-3 supplementation on sertraline continuous therapy to reduce depression or anxiety symptoms: A systematic review and meta-analysis. Psychiatry Research. 2021; 296:113652-.
  • Gao X, Su X, Han X, Wen H, Cheng C, Zhang S, et al. Unsaturated Fatty Acids in Mental Disorders: An Umbrella Review of Meta‐Analyses. Advances in Nutrition. 2022; 13(6):2217-36.
  • Kelaiditis CF, Gibson EL, Dyall SC. Effects of long-chain omega-3 polyunsaturated fatty acids on reducing anxiety and/or depression in adults; A systematic review and meta-analysis of randomised controlled trials. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2023; 192:102572-.
  • Liao Y, Xie B, Zhang H, He Q, Guo L, Subramaniapillai M, et al. Efficacy of omega-3 PUFAs in depression: A meta-analysis. Translational Psychiatry. 2019; 9(1):190-9.
  • Mocking RJT, Harmsen I, et al. Meta-analysis and meta-regression of omega-3 polyunsaturated fatty acid supplementation for major depressive disorder. Translational psychiatry. 2016; 6(3), e756.
  • Wolters M, von der Haar A, Baalmann A-K, Wellbrock M, Heise TL, Rach S. Effects of n‐3 polyunsaturated fatty acid supplementation in the prevention and treatment of depressive disorders— a systematic review and meta‐analysis. Nutrients. 2021; 13(4):1070.

Last reviewed and updated: 14 August 2023