Fish Oil

Last Updated: December 18, 2023

Fish oil is a source of omega-3 fatty acids. It reduces triglycerides, but does not seem to affect the rate of cardiovascular events. It seems to notably reduce the symptoms of depression and improve some painful, inflammatory conditions.

Fish Oil is most often used for

What is fish oil?

Fish oil is the go-to source for two long-chain omega-3 (a.k.a. n-3) polyunsaturated fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Fish oil can be consumed in the diet (from foods like salmon or anchovies), and is also available as a dietary supplement and as a prescription drug. The role of fish oil in cardiovascular disease, cancer, and many other conditions is a field of considerable interest and research.[1]

According to recent analyses of NHANES, over 20% of the population in the United States takes an omega-3-containing dietary supplement.[2]

What are fish oil’s main benefits?

Fish oil is best known for its ability to reduce triglyceride levels in the blood, for which prescription fish oil is best studied.[3] Fish oil also seems to modestly reduce blood pressure, especially in people with hypertension.[4] Despite this, a meta-analysis of large clinical trials shows that taking fish oil for at least 1 year does not reduce the rate of cardiovascular events.[5] Most analyses suggest a modest benefit of fish oil for depression,[6][7][8][9] but this benefit may be too small to make a difference in people with major depressive disorder.[8][10] Limited evidence suggests that fish oil may have some benefit for inflammatory conditions like systemic lupus erythematosus and rheumatoid arthritis.[11]

What are fish oil’s main drawbacks?

Fish oil is usually well-tolerated and safe. Common side effects from taking fish oil supplements include stomach pain, fishy breath and burps, heartburn, nausea, and diarrhea. Also, some fish oil formulations have been linked to increased levels of low-density lipoprotein (LDL) cholesterol. Fish oil supplements are not strictly regulated, and some may contain contaminants, oxidized fatty acids, saturated fats, and other impurities that may reduce the overall benefit of the supplement. Fish oil has antiplatelet effects, although most clinical research has not found that supplementation with fish oil increased bleeding risk. A large 5-year study in Japan did find a small increase in bleeding in people taking prescription eicosapentaenoic acid (EPA), though.[3]

How does fish oil work?

Fish oil reduces triglyceride levels by decreasing triglyceride-rich lipoprotein synthesis and release by the liver. It may also increase clearance of triglycerides by upregulating the lipoprotein lipase enzyme.[3] EPA and DHA from fish oil are usually initially incorporated into the phospholipid layer of cell membranes in platelets, neutrophils, and red blood cells. EPA especially seems to stabilize cell membranes and inhibit lipid oxidation, which can help regulate vascular tone, improve cell signaling, and reduce inflammation.[12]

What are other names for Fish Oil?
Note that Fish Oil is also known as:
  • Eicosapentaenoic Acid
  • EPA
  • Docosahexaenoic Acid
  • DHA
  • Omega-3 fatty acids
  • Omega-3
  • Omega 3
  • N-3 Fatty Acids
Fish Oil should not be confused with:
  • Alpha-Linolenic Acid (the plant-based omega-3)
Dosage information

Fish oil doses vary depending on the goal of supplementation. For general health, 250 mg of combined EPA and DHA is the minimum dose and can be obtained via fish intake. The American Heart Association recommends 1 g daily.

Since fish oil is a combination of two different fatty acids, these numbers reflect a combined total. Total eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) consumption should come from a mix of real food and supplements. The more EPA and DHA is provided by the diet, the less supplementation is required.

Fish oil can be taken throughout the day. To minimize the "fish burp" taste, take fish oil with meals.

Pregnant women should increase their intake of DHA by at least 200mg a day, as long as there is no risk of elevated mercury levels.

Examine Database: Fish Oil