Fish oil supplements don’t help everyone.

While omega-3 fatty acids in fish oil can lower triglycerides and may support heart health, high doses have been linked to a higher risk of atrial fibrillation (AFib). People with AFib have an increased risk of stroke, blood clots, and heart failure.

What Does Research Say About Fish Oil and Heart Health?

For patients with heart disease, fish oil supplements can reduce inflammation and improve heart function. However, a meta-analysis shows that taking one gram or more of omega-3s per day is linked to a 49% increased risk of AFib.

A typical fish oil supplement contains about 180 mg of eicosapentaenoic acid (EPA) and 120 mg of docosahexaenoic acid (DHA)—the two major types of omega-3s. However, the formulations and dosages can vary widely from brand to brand.

While there’s no official safety limit for omega-3 consumption, the Food and Drug Administration (FDA) said that dietary supplements providing no more than 5 grams of EPA and DHA per day are safe when used as recommended or suggested in their labeling.

In a study conducted by the American Heart Association, a daily dose of 4 grams of combined EPA and DHA are effective at treating very high triglycerides.

How to Decide Whether Fish Oil Is Right for You

The USDA recommends that most adults eat at least 8 ounces of seafood each week to get omega-3s.

“If your intake is less, then a fish oil supplement may be helpful,” said Lena Beal, MS, RDN, LD, a spokesperson for the Academy of Nutrition and Dietetics.

However, eating fatty fish like salmon, sardines, and herring is better for heart health than just using supplements, Beal added. While there’s no evidence that fish oil supplements reduce the risk of heart disease, people who consume seafood one to four times per week have a lower chance of dying from heart disease.

Most experts recommend prioritizing omega-3s from dietary sources like oily fish instead of supplements because whole foods contain additional beneficial nutrients.