New analysis published in the Journal of the American Heart Association finds that higher circulating blood levels of omega-3 fatty acids are associated with a significantly lower risk of developing atrial fibrillation (AF).
This is in contrast to previous findings from the UK Biobank that linked higher doses of omega-3s from fish oil supplements to increased risk of AF.
The comprehensive biomarker-based study — one of the largest of its kind — analysed data from hundreds of thousands of participants in the UK Biobank.
Researchers showed that individuals with higher omega-3 levels had a lower incidence of AF during a median 12.7 years of follow-up, compared to those with lower omega-3 status.
Importantly, when properly accounting for the confounding effects of age in the statistical models, reported fish oil supplement use was not associated with an increased risk of atrial fibrillation.
"These results reinforce that it’s the physiologic status of omega-3 in the blood — not simply supplementation per se — that correlates with AF risk," said Dr Bill Harris, President of the Fatty Acid Research Institute (FARI) and senior investigator on the paper.
"In properly adjusted models, supplement use showed no increase in AF risk."
This biomarker-based approach provides a more nuanced understanding than studies that rely solely on self-reported supplement usage or dose and aligns with a broader body of evidence showing cardiovascular benefits of omega-3 fatty acids.
Key takeaways from the study
Higher circulating omega-3 fatty acid levels were associated with significantly lower incident AF risk in multivariable models.
After careful statistical adjustment, fish oil supplement use itself was not linked with a higher AF risk.
These findings correct the conclusions of previous studies that mistakenly reported (due to improper statistical analysis) that fish oil supplement use increased the risk for atrial fibrillation.
"From a clinical standpoint, these findings help clarify an important misconception," Dr Harris explained.
"When we look at objectively measured blood omega-3 levels, higher status is associated with lower risk of atrial fibrillation — not higher."
"This reinforces the importance of evaluating physiology, not assumptions about supplements. Concerns raised by earlier reports linking fish oil use to atrial fibrillation were likely driven by methodological limitations."
"When age is modelled appropriately, fish oil supplement use does not increase atrial fibrillation risk."
Dr James O’Keefe, Director of Preventive Cardiology at St. Luke’s Mid-America Heart Institute, Professor of Medicine at the University of Missouri, Kansas City and co-author on this paper, commented: “This study found that higher omega-3 blood levels correlate with lower risks for atrial fibrillation (AFIB) during long-term follow-up."
"This is in line with other recent studies our group has done, which show that omega-3 in doses typically achieved with consumption of fish/seafood and/or omega-3 over-the-counter supplements reduces the risk of AFIB."
"The only signal for increased AFIB risk comes in people treated with very high-dose omega-3, such as pharmacologic, prescription-strength omega-3 products, used in people at high risk for AFIB."
"For the vast majority of people, omega-3 intake is a safe and effective nutrient for supporting long-term heart and brain health."