Study: Omega-3 fatty acid and vitamin D supplements didn't alter atrial fibrillation

A tablet displays a 3D image of a heart and sits beside a stethoscope and medical records.

Atrial fibrillation, an irregular heart rhythm, affects about 46 million people worldwide, but becomes more common with age and can increase the risk for heart failure or stroke. Observational studies have found people with lower levels of omega-3 fatty acids and vitamin D have had higher incidents of atrial fibrillation. However, research has shown mixed results about the impact these supplements have on preventing atrial fibrillation. Some studies suggested benefits. Others found risks. After conducting a randomized, controlled trial with more than 24,000 adults, researchers concluded that omega-3 fatty acid and/or vitamin D supplements didn’t have a significant impact on atrial fibrillation occurrence.

To reach these findings, researchers recruited study participants ages 50 and older, and who didn't have an irregular heart rhythm, into a five-year trial. Then, they assessed how omega-3 and/or vitamin D supplements overlapped with future incidents of atrial fibrillation or heart flutter. Participants were divided into groups to test the effectiveness of omega-3 fatty acid supplements, measured by 460 mg of eicosapentaenoic acid (EPA) and 380 mg of docosahexaenoic acid (DHA); a vitamin D supplement, measured by 2,000 IU of vitamin D3; or a combination of EPA/DHA and vitamin D3 supplements. A control group received olive oil and soybean oil. During this time, 900 people, about 3.6% of study participants, experienced atrial fibrillation. There was no significant difference among the groups. 

The study published in JAMA and was supported by the National Heart, Lung, and Blood Institute, the Office of Dietary Supplements, the National Institute of Neurological Disorders and Stroke, the National Center for Complementary and Integrative Health, and the National Institute of Diabetes and Digestive and Kidney Diseases.