Fish oil

Also known as omega 3 fish oil, fishoil, marine oil.

Last reviewed October 9, 2026 · Jump to references

What is Fish oil?

In plain words

Fish oil contains omega-3 fats called EPA and DHA. The body builds these fats into cell membranes and uses them to make signals involved in inflammation. Researchers study fish oil for its effects on blood fats, heart health, and inflammation. Evidence for heart benefits varies by product and population, and ordinary fish oil supplements are not equivalent to prescription products.

Technical definition

Fish oil is a mixture of lipids derived from fish tissues, containing the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA; 20:5 n-3) and docosahexaenoic acid (DHA; 22:6 n-3). EPA and DHA are incorporated into cell membranes and converted into lipid signaling molecules; they influence inflammatory signaling and hepatic triglyceride metabolism rather than acting through a single receptor. In the United States, fish oil is sold as a dietary supplement without FDA approval for disease treatment, while specific prescription omega-3 formulations are FDA-approved for defined indications.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.