Marine omega-3 supplementation may promote atrial fibrillation

Supplementation with marine omega-3 fatty acids appears to contribute to an increased risk of atrial fibrillation (AF), especially at higher doses, according to the results of a meta-analysis.

Researchers searched multiple online databases for randomized controlled trials that evaluated the effects of marine omega-3 supplementation on cardiovascular outcomes and reported results for AF as a prespecified outcome, an adverse event, or a cause for hospitalization. The trials had to have a minimum sample size of 500 patients and a median follow-up of ≥1 year.

Of 4,049 screened records, seven studies were selected for inclusion in the meta-analysis. There was a total of 81,210 patients (mean age 65 years, 39 percent female) across seven trials, among whom 58,939 (72.6 percent) were enrolled in trials testing ≤1 gram per day (g/d) of omega-3 fatty acids and 22,271 (27.4 percent) in trials testing >1 g/d. The weighted average follow-up was 4.9 years.

Pooled data showed that compared with nonusers, users of marine omega-3 fatty acid supplements had about a 25-percent higher risk of AF (n=2,905; hazard ratio [HR], 1.25, 95 percent confidence interval [CI], 1.07–1.46; p=0.013).

In analyses stratified by dose, the risk increase associated with marine omega-3 supplementation was greater in the trials testing >1 g/d (HR, 1.49, 95 percent CI, 1.04–2.15; p=0.042) than in trials evaluating lower doses (≤1 g/d; HR 1.12, 95 percent CI, 1.03–1.22; p=0.024; p_interaction<0.001).

In meta-regression analysis, each 1-gram increase in omega-3 fatty acids dosage translated to an 11-percent increase in the risk of AF (HR, 1.11, 95 percent CI, 1.06–1.15; p=0.001).