Omega-3 and Fish Oil Supplements: What the Evidence Really Says

Eating oily fish is linked to better heart health. But swallowing a fish oil capsule isn’t the same as eating fish. Large studies of supplements in healthy people have mostly been disappointing, although some specific prescriptions help some patients.

Imagine buying fish oil capsules every month for years to protect your heart, while rarely eating actual fish. You assume they’re doing something. The evidence suggests your money might be better spent on two portions of fish a week, and some walking shoes.

What the evidence shows

• For most healthy people, omega-3 supplements don’t clearly reduce heart attacks, strokes or deaths
• High-dose prescription omega-3 can lower high triglycerides, and one specific form reduced heart events in some high-risk patients
• Some studies suggest a small increase in atrial fibrillation with higher doses
• Evidence for brain health, joints and mood is mixed

Getting omega-3 from food

Oily fish such as salmon, sardines, mackerel, herring and trout are rich sources. Many health bodies recommend around two portions of fish a week, one of them oily. Plant sources such as walnuts, flaxseed and chia contain a different form that the body converts only in small amounts. Algae-based supplements are an option for vegans.

But are there risks?

Fish oil can increase bleeding risk, especially with blood thinners, and cause fishy burps and upset stomach. Pregnant women should follow advice on which fish to eat because of mercury, and avoid cod liver oil supplements, which contain vitamin A.

Sources: US National Center for Complementary and Integrative Health (Omega-3 supplements), American Heart Association, NHS (Fish and shellfish), Cochrane review of omega-3 for cardiovascular disease. This guide is for general information and does not replace advice from your own nurse, doctor, dietitian or pharmacist.