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Fish Oil

Also known as: Omega-3 fatty acids, Omega-3, Omega 3, N-3 Fatty Acids

Overview

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.

Benefits

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. 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.

How it works

Fish oil is best known for its ability to reduce triglyceride levels in the blood, for which prescription fish oil is best studied. Fish oil also seems to modestly reduce blood pressure, especially in people with hypertension. 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. Most analyses suggest a modest benefit of fish oil for depression, but this benefit may be too small to make a difference in people with major depressive disorder. Limited evidence suggests that fish oil may have some benefit for inflammatory conditions like systemic lupus erythematosus and rheumatoid arthritis.

Side effects

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.

Dosage

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.

FAQs

What is fish oil?

What are fish oil’s main benefits?

What are fish oil’s main drawbacks?

Does fish oil really help depression?

A meta-analysis of 35 small, randomized trials found that fish oil can slightly improve depression when compared to control. However, this improvement may be too small to be noticeable. Also, adding fish oil to antidepressant medication seems to be more beneficial than antidepressant treatment alone. Fish oil incorporates into the cell membrane phospholipid layer, increasing its fluidity and permeability, which in turn might reduce inflammation and attenuate depressive symptoms. Another meta-analysis suggested that doses of 1-2 grams daily containing ≥60% proportion of total EPA + DHA seem to be especially beneficial.

Can I eat flax seeds instead of fish or fish oil for omega-3s?

The short answer is “yes”, but it ultimately depends on your goal. For the purpose of covering the minimum amount of omega-3 fatty acids required for general health, it’s not necessary to consume fish or fish oil; you can just eat flaxseed. Flaxseed is a rich source of alpha-linolenic acid (ALA), the only essential omega-3 fatty acid (i.e., the only omega-3 that can’t be synthesized by the body). Following ingestion, ALA is converted into the longer chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the same fatty acids found in fish oil.

Does fish oil increase the risk of atrial fibrillation (irregular heart beat)?

There are some mixed views on whether fish oil can cause abnormal heart rhythms or not. Generally speaking, most healthy people don’t need to worry: A meta-analysis of 30 randomized studies and 77,990 patients shows that taking fish oil does not affect the risk of atrial fibrillation. However, in people who have (or are at risk for) heart disease, there’s a possibility that fish oil can increase the risk of new-onset atrial fibrillation.

Can fish oil increase the risk of bleeding?

For most people, regular fish oil supplements do not affect bleeding risk. One meta-analysis of 11 randomized studies with over 80,000 patients concluded that fish oil does not increase bleeding risk. Interestingly, the latter meta-analysis noted that EPA-only supplements did increase bleeding risk compared to control, but the absolute increase in risk was very small: about 0.5%, suggesting that for every 200 people taking an EPA-only supplement, one might experience bleeding.