Healthy adults who take fish oil supplements could be at greater risk of suffering heart attack or stroke for the first time, study finds

Healthy adults who take fish oil supplements may be at greater risk of heart problems for the first time, a study suggests.

As a rich source of omega-3 fatty acids, fish oil is often recommended as a dietary preventative to prevent the development of cardiovascular disease. Several other beneficial effects are also attributed to it, such as relieving joint pain.

But new research suggests that taking the popular supplement could actually increase the risk of heart disease and stroke in healthy adults, while reducing the risk in people with a history of disease.

The study, which involved more than 415,000 Britons, looked at the associations between fish oil supplements and new cases of atrial fibrillation, heart attacks, strokes, heart failure and death.

They assessed the potential of these supplements on the risk of transitioning from good heart health, classified to the secondary stage of atrial fibrillation, the third stage of major cardiovascular events such as heart attack and death.

The study, which involved more than 415,000 Brits, looked at the associations between fish oil supplements and new cases of atrial fibrillation, heart attacks, strokes, heart failure and death (Stock Photo)

Nearly a third (130,365) of participants aged 40 to 69 said they regularly used fish oil supplements, including large numbers of older white people and women.

Alcohol intake and the ratio of oily to non-oily fish eaten were also higher, while the numbers of current smokers and people living in deprived areas were lower.

During an average follow-up of 12 years, 18,367 people developed the abnormal heart rhythm disorder atrial fibrillation, 22,636 had a heart attack or stroke or developed heart failure, and 22,140 died – 14,902 without atrial fibrillation or heart disease.

Of those who progressed from good heart health to atrial fibrillation, 3085 developed heart failure, 1180 had a stroke and 1415 had a heart attack.

About 2,436 of the people with heart failure died, along with 2,088 who had a stroke, and 2,098 after a heart attack, according to findings published in BMJ Medicine.

Regular use of fish oil supplements played several roles in cardiovascular health, disease progression and death, the findings showed.

Those who used them regularly without signs of illness had a 13 percent higher risk of developing atrial fibrillation and a five percent higher risk of stroke.

But among those who had cardiovascular disease to begin with, regular use of fish oil supplements reduced the risk of progressing from atrial fibrillation to heart attack by 15 percent and from heart failure to death by 9 percent.

The risk of transitioning from good health to heart attack, stroke or heart failure was six percent higher in women. It was also six percent higher among non-smokers among fish oil users.

Meanwhile, the protective effect of these supplements on the transition from good health to death was greater in men (seven percent lower risk) and older participants (11 percent lower risk).

Alcohol intake and the ratio of oily to non-oily fish eaten were also higher, while the numbers of current smokers and people living in deprived areas were lower (Stock Photo)

Led by Sun Yat-Sen University, China, researchers admit there are limitations to the study, including that the dosage and formulation of fish oil was not recorded, which experts say could be key to the results.

Nevertheless, they conclude: ‘Regular use of fish oil supplements could play several roles in the progression of cardiovascular disease.

‘Further research is needed to determine the precise mechanisms for the development and prognosis of cardiovascular disease with regular use of fish oil supplements.’ It’s not the first study to draw such conclusions in a 2018 Cochrane review of research that compared 79 studies and found it made “little or no difference to the risk of cardiovascular events, coronary heart deaths, coronary heart disease, stroke or heart irregularities’.