Fish oil supplementation sometimes seems to be recommended for everything, but does it really work? MoodSurfing follows the science so you don’t have to.
First the main conclusion: a healthy diet is important. Everyone is recommended to eat fish at least twice a week, especially ocean fish: salmon, mackerel, herring, and sardines. Canned or fresh, these fish provide the type of fatty acids that our brains and bodies require. Also, of course, cut back on fried and heavily processed foods and eat more fruits and vegetables. As always, we recommend the Mediterranean diet for guidance on meal plans and recipes.
If you are doing that, you probably don’t need to worry about supplementation of fish oil. You can get all you need from food. There is no evidence that increasing more and more omega 3’s in the diet will be better than the amount you can get from eating ocean fish regularly.
Specific uses for omega 3’s
Depression and mood swings. Some effect is found in lowering the risk of depression with fish consumption, but fish oil supplementation has not been shown to have more than a small-to-moderate effect, and should only be considered as a secondary intervention, it doesn’t replace other treatments for depression. Again, diet is better than supplementation.
Alzheimer’s disease, dementia and cognitive function. Prospective cohort studies have found that people who eat more fish have a lower risk of Alzheimer’s disease or cognitive decline, but they have not been able to replicate these results with fish oil supplementation. It may be that eating fish over a lifetime is what gives protection, or it may be that people who show a lack of omega 3’s are metabolizing it differently, so that no matter how much they take in, there is less overall effect. More research is needed on these issues.
Cardiovascular Disease. The National Institute of Health says: “Overall, research indicates that consuming fish and other types of seafood as part of a balanced diet promotes heart health, especially when the seafood is consumed in place of less healthy foods. Fish oil and other LC omega-3 supplements lower triglyceride levels and might reduce the risk of some cardiovascular endpoints, especially among people with low dietary omega-3 intakes. Evidence of a protective effect for omega-3 supplementation is stronger for people with existing coronary heart disease than for healthy individuals.” (NIH website: Omega 3 Fatty Acids: Fact Sheet for Health Professionals. Accessed Aug. 3, 2026).
So break out those summer seafood recipes and enjoy! Remember, canned fish, like salmon, mackerel or sardines can also provide needed nutrients if fresh seafood is difficult to obtain.
References:
Li F, Liu X, Zhang D. Fish consumption and risk of depression: a meta-analysis. J Epidemiol Community Health 2016;70:299-304. [PubMed abstract]
Appleton KM, Sallis HM, Perry R, Ness AR, Churchill R. Omega-3 fatty acids for depression in adults. Cochrane Database Syst Rev 2015;11:CD004692. [PubMed abstract]
Yassine H, Pour S, Juarez M et al.
CNS target engagement of high-dose DHA supplementation in older adults at risk for dementia: a randomised, double-blind, placebo-controlled trial
eBioMedicine, 2026; 129