General description
Fish oil is a dietary source of omega-3 fatty acids. The body needs omega-3 fatty acids for many functions, from muscle activity to cell growth.
Omega 3 fatty acids come from food. The body cannot manufacture them. Fish oil contains two omega 3s called docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Sources of DHA and EPA are fatty fish, such as salmon, mackerel, and trout, and shellfish, such as mussels, oysters, and crab. Some nuts, seeds, and vegetable oils contain another omega 3 called alpha-linolenic acid (ALA).
Fish oil supplements come in liquid, capsule, and pill forms.
People take fish oil for its anti-inflammatory effects.
Evidence
In research on the use of fish oil for specific conditions, the following have been shown:
- Heart disease. Although research indicates that people who ingest dietary sources of fish oil at least twice a week have a lower risk of dying from heart disease, taking fish oil supplements appears to have little or no benefit for heart health .
- High blood pressure. Several studies report modest reductions in blood pressure in people taking fish oil supplements. There is some evidence that the beneficial effects of fish oil might be greater for people with moderate to severe high blood pressure than for people with a mild increase in blood pressure.
- High triglycerides and cholesterol. There is clear evidence that omega-3 fatty acids can significantly lower blood triglyceride levels. There also appears to be a slight improvement in high-density lipoprotein (HDL or “good”) cholesterol, although an increase in low-density lipoprotein (LDL or “bad”) cholesterol was also seen.
- Rheumatoid arthritis. Studies suggest that fish oil supplements may help reduce pain, improve morning stiffness, and ease joint tenderness in people with rheumatoid arthritis. While the relief is usually modest, it may be enough to reduce the need for anti-inflammatory medications.
Our recommendation
They are generally safe
Omega 3 fatty acids are essential for good health. Try to get them from your diet by consuming fish, grilled or baked, not fried. Fish oil supplements may be helpful if you have high triglyceride levels or rheumatoid arthritis.
Fish oil appears to contain almost no mercury, which can be a concern in certain types of fish. While generally safe, consuming too much fish oil can increase your risk of bleeding and may suppress your immune response. It’s not clear if fish oil is safe for people with shellfish allergies. Take fish oil supplements under the supervision of a doctor.
Safety and side effects
If taken as directed, fish oil supplements are generally considered safe.
However, fish oil supplements can cause mild side effects, including the following:
- Fishy taste
- Bad breath
- Heartburn, nausea or diarrhea
- Rash
Taking high-dose fish oil supplements can increase the risk of bleeding and possibly increase the risk of stroke.
Interactions
Here are some of the possible interactions:
- Anticoagulants and antiplatelets, herbal medications and supplements. These types of medications, herbal medications, and supplements reduce blood clotting. Fish oil supplements may increase the risk of bleeding.
- Blood pressure medications, herbal medications, and supplements. Taking fish oil supplements might slightly lower blood pressure. Taking these supplements with blood pressure medications might increase the effects on blood pressure.
- Some contraceptives might interfere with the effect of fish oil on triglycerides.
- Orlistat (Xenical, Alli). Taking fish oil with this weight loss medication might decrease the absorption of fatty acids from fish oil. Consider taking the supplement and medication two hours apart.
- Vitamin E. taking fish oil can lower vitamin E levels.
