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.^[1] 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. Several meta-analyses of randomized studies at least one year long in people with or at risk for cardiovascular disease show that fish oil can increase the risk of new-onset atrial fibrillation compared to control.^[2][3][4] It’s important to note that, while this increase in risk is statistically significant, it’s still small in absolute terms and there is no known mechanism to explain this risk.