Study Finds Link Between Fish Oil Supplements and Stroke risk

According to a study published in BMJ Medicine, regular use of fish oil supplements might increase the risk of first-time heart disease and stroke among those in good cardiovascular health but may slow the progression of existing poor cardiovascular health and lower the risk of death.

Cardiovascular disease is the leading cause of death worldwide, accounting for about one-sixth of overall mortality.

Fish oil, a rich source of omega-3 fatty acids, containing eicosapentaenoic acid and docosahexaenoic acid, has been recommended as a dietary measure to prevent cardiovascular disease. Although some epidemiological and clinical studies have assessed the effect of omega 3 fatty acids or fish oil on cardiovascular disease and its risk factors, the findings are inconsistent.

In the study, researchers analysed data from 415,737 UK Biobank participants, aged 40-69, to estimate the association between fish oil supplements and the risk of new cases of atrial fibrillation, heart attack, stroke, heart failure, and death. They assessed the progression from good heart health to atrial fibrillation, major cardiovascular events, and death. Their health was tracked using medical records until March 2021 or until death.

The results showed that nearly a third (31.5%) of the participants regularly used fish oil supplements. Over an average monitoring period of nearly 12 years, 18,367 developed atrial fibrillation, 22,636 experienced a heart attack, stroke, or heart failure, and 22,140 died.

Regular fish oil supplement use was linked to a 13% higher risk of atrial fibrillation and a 5% higher risk of stroke for those with no known cardiovascular disease at the start. Conversely, for those with cardiovascular disease, fish oil supplements were associated with a 15% lower risk of heart attack following atrial fibrillation and a 9% lower risk of death following heart failure.

The findings revealed that regular use of fish oil supplements and the risk of transitioning from good health to heart attack, stroke, or heart failure was 6% higher in women and 6% higher in non-smokers. And the protective effect of these supplements on the transition from good health to death was greater in men (7% lower risk) and older participants (11% lower risk).

“Regular use of fish oil supplements might have different roles in the progression of cardiovascular disease. Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease events with regular use of fish oil supplements,” said the study authors.

Reference: Chen G, Qian Z(, Zhang J, et al.; Regular use of fish oil supplements and course of cardiovascular diseases: prospective cohort study; BMJ Medicine 2024;3:e000451. doi:10.1136/bmjmed-2022-000451