An emerging body of research suggests a correlation between taking fish oil and developing new or worsening Afib.

A 2021 meta-analysis, for example, found an increase in the risk of Afib in people taking fish oil compared with those taking a placebo. However, doses in the study varied greatly, from 0.84 to 4 grams (g) per day.

As with most health risk factors, researchers have not found a clear causal link between taking fish oil and developing Afib. Instead, some studies show a correlation between the long-term use of fish oil and the long-term risk of Afib.

According to another 2021 meta-analysis of randomized controlled trials, this risk may be dose-related. It states that at doses above 1g per day, there was a 10 to 11% higher relative risk of Afib events per 1 g increase in daily supplementation.

The absolute risk was still low, at 1.3% among participants in the group taking a placebo and 2.2% in those taking omega-3. Researchers are not sure why fish oil appears to be associated with an increased risk of Afib. However, they suggest omega-3s may change calcium, sodium, and potassium currents in the heart, elevating Afib risk.

Some research on fish oil and Afib has suggested fish oil may reduce the risk of Afib. However, most existing studies suggest a correlation between taking high doses of omega-3 and an increased risk of Afib.

People with Afib can consult a cardiologist or primary care provider about the risks and benefits of fish oil.

If a person has other cardiovascular risk factors, such as high cholesterol, that mean they may benefit from fish oil use, taking a dose of less than 1 gram per day may be the safest option.

People who develop Afib or whose symptoms get worse when taking fish oil should stop taking it and contact a healthcare professional.

• an irregular or very fast heartbeat
• a fluttery feeling or thumping in the chest
• feeling weak, confused, or dizzy along with an irregular heartbeat

Afib is usually a sign of underlying heart or blood vessel issues.

People with Afib should develop a treatment plan with their healthcare professional. This may include medications such as blood thinners.

In some cases, a doctor may recommend cardioversion or ablation, which are medical procedures to treat Afib.

Lifestyle changes, such as eating a healthy diet, managing weight, and exercising more frequently may reduce overall heart health risks. A person may also lower their risk of Afib episodes by drinking less caffeine and avoiding alcohol.

Cardiologists often recommend fish oil to help manage triglyceride levels and reduce the risk of high blood pressure, heart attacks, and strokes in some people.

However, fish oil is not appropriate for everyone. High doses of fish oil might increase a person’s risk of Afib, especially if they have other risk factors.

People with Afib should avoid supplements that can cause heart arrhythmias, such as energy supplements containing caffeine. High doses of fish oil may also be associated with an increased risk of Afib.

People taking blood thinners may have a higher risk of bleeding if they take fish oil supplements. Some evidence also suggests that taking high doses of fish oil correlates with a higher risk of Afib. It is best to talk with a doctor before trying any supplement, since they all have benefits and risks.

Fish oil offers a number of potential heart health benefits. Most notably, it can improve cholesterol levels. For this reason, many cardiologists recommend fish oil or omega-3 fatty acid supplements.

However, some research suggests fish oil may increase the risk of atrial fibrillation (Afib). It is best to speak with a doctor before trying fish oil. People who develop Afib while taking fish oil should stop taking the supplement and talk with their doctor.