Moderate omega-3 blood status is linked to lower atrial fibrillation risk in a large population study. Digest
Irregular heart rhythms become more common with age, and there is ongoing debate about whether omega-3 fatty acid intake reduces the risk of atrial fibrillation (AFib) or may, in some cases, actually increase it. To address this uncertainty, researchers analyzed health data from the UK Biobank.
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The study included adults aged 40 to 69 who did not have AFib at baseline. 261,108 participants had blood tests measuring omega-3 levels, and 466,169 reported whether they used fish oil supplements. Participants were followed for an average of 12.7 years.
- When comparing the highest and lowest quintiles of total omega-3 levels, participants with an estimated average omega-3 index of approximately 8.6% had a 14% lower risk of developing AFib over the study period than those at lower levels.
- In absolute terms, about 7.5% of people in the lowest total omega-3 group developed AFib, compared with about 6.9% in the highest group.
- Prior UK Biobank reports suggesting a higher AFib risk among fish oil supplement users were reproduced only when participants were split into broad age groups. This approach may be insufficient, since both supplement use and AFib increase with age.
- When age was handled in a more nuanced way, rather than grouping everyone above or below a single age limit, fish oil supplement use was no longer linked to AFib.
Omega-3 fatty acids may influence heart rhythm because they can become part of heart-cell membranes. That could change how heart cells generate electrical activity and how they respond to physical stretch and signals from the nervous system. These effects may depend on dose, with moderate exposure supporting stability, while very high doses could push the same membrane and nerve-related pathways toward AFib. This dose-sensitive framing helps reconcile these new findings with studies that reported increased AFib risk at high omega-3 doses. That said, just looking at the dose oversimplifies the interpretation of different study results. In this clip, I highlight key nuances that should be considered when evaluating findings from earlier studies reporting an increased risk of AFib with omega-3 supplementation.