New Research Clarifies When Omega-3s May Raise AFib Risk

Omega-3 fatty acids have long been promoted for heart health, but a string of meta-analyses in recent years raised a troubling question: Could these supplements actually increase the risk of atrial fibrillation (AFib), the most common type of irregular heartbeat? Those earlier reports, however, were based on a small slice of the evidence, no more than eight randomized trials each, and often left out studies where AFib data existed but had never been published.

A new meta-analysis published in Circulation: Arrhythmia and Electrophysiology, led by researchers affiliated with the Fatty Acid Research Institute (FARI), set out to close that gap. The team pulled together 35 randomized controlled trials representing 37 data sets and 114,592 participants, including 15 trials with previously unpublished AFib data. Importantly, they also included trials that reported zero AFib events, a step that helps correct for publication bias, since studies with null results are less likely to get published in the first place.

Dose and Risk Status, Not Omega-3s Alone

Rather than treating omega-3 supplementation as a single, uniform exposure, the team tested whether AFib risk depended on two factors working together: the daily dose of EPA and DHA (above or below 1,500 milligrams per day) and whether participants already had high cardiovascular disease risk.

The pattern that emerged was specific. Only one group, people at high cardiovascular risk taking high doses of EPA/DHA (above 1,500 mg/day), showed a statistically significant increase in AFib risk, with 43% higher odds and an absolute risk difference of less than 1 percentage point. The other three groups, including high-risk patients on low doses and low-risk patients on either dose, showed no significant increase in AFib risk.

“Our findings show that the relationship between omega-3s and atrial fibrillation is much more nuanced than previous headlines suggested,” said senior investigator William S. Harris, Ph.D., president of FARI. “For the vast majority of people taking nutritional doses of omega-3s, these data should provide reassurance that there is no meaningful increase in atrial fibrillation risk.”

Separating Supplement Shelves From Prescription Bottles

The distinction matters because omega-3 products span a wide range of doses and purposes. Nutritional supplements, typically 500 to 1,500 milligrams per day, are commonly used to support general cardiovascular wellness. Pharmacological formulations, typically 2 to 4 grams per day, are prescribed specifically for people with elevated triglycerides or established heart disease.

The study authors argue that AFib risk should be evaluated separately for these two categories rather than lumped together, since the clinical stakes and the populations taking them are different.

Weighing Risk Against Established Benefit

Investigators noted that even in the high-risk, high-dose group where AFib risk did increase, that risk needs to be weighed against the cardiovascular benefits documented in major clinical trials of high-dose EPA, including reductions in heart attacks and strokes. The authors describe the AFib increase as small relative to those benefits, though they call for further prospective research to better define how the trade-off plays out for individual patients.

“The decision to take or discontinue omega-3 supplements should be a discussion between a patient and his/her health care provider,” said Harris. “What this study does is provide clinicians with better guidance on which patients may benefit from closer monitoring when using high-dose omega-3 therapies while reassuring consumers that it is safe to consume omega-3 fatty acids from foods and dietary supplements.”