Fish oil supplements increased the risk of atrial fibrillation and stroke in healthy subjects
Analysis of data from the British Biobank has shown that regular consumption of fish oil supplements can be considered a risk factor for atrial fibrillation and stroke. However, as reported in BMJ Medicine, in patients with cardiovascular abnormalities, such supplements may reduce the risk of disease progression.
Fish oil supplements are high in omega-3 fatty acids and are often recommended as a dietary aid to prevent cardiovascular disease. That said, the results of studies examining the effects of fish oil on the progression of cardiovascular disease are conflicting. Specifically, some of the studies limited the study population to people with certain cardiovascular diseases or at high risk of cardiovascular disease, while others evaluated databases on the general population. These factors may preclude a direct comparison of the effects of omega-3 fatty acids on the development of atrial fibrillation or on further worsening of cardiovascular disease.
A team of researchers from the UK, China and the US, led by Hualiang Lin from Sun Yat-sen Zhongshan University, suggested that fish oil supplements may have different effects on cardiovascular disease risk in patients with different health conditions. In total, the researchers analysed data from 415737 UK biobank participants aged 40-69 years (mean age 55.9 years), of whom 31.4 percent reported regular use of fish oil supplements.
Over a mean follow-up period of 11.9 years, 18367 participants had atrial fibrillation and 17826 participants had serious adverse cardiovascular events. Analysis of state transitions showed that for healthy individuals, fish oil supplementation had a detrimental effect: the adjusted relative risk of atrial fibrillation was 1.13. The relative risk of stroke in this cohort was 1.05.
Meanwhile, in patients with atrial fibrillation, regular fish oil supplementation reduced the risk of serious adverse cardiovascular events (risk ratio 0.92) and death (relative risk 0.91). Notably, in healthy subjects, fish oil supplementation reduced the risk of heart failure, and in patients with atrial fibrillation, it reduced the risk of myocardial infarction. In patients with heart failure, the researchers found a protective effect of regular fish oil supplementation on the risk of death.
The researchers also found that the association between regular fish oil supplementation and the risk of progression from healthy to serious adverse cardiovascular events was higher in women (p = 0.005) and in non-smoking participants (p = 0.005). In addition, the protective effect of fish oil supplementation was more prominent in older adults.
According to the scientists, this study shows the multidirectional effect of fish oil supplements in different population cohorts. This means that physicians should be more careful when prescribing such supplements, but further research is needed to determine the exact mechanisms of the effect of fish oil supplements on cardiovascular disease risk.