Fish oil supplements are known for cardiovascular benefits. But should healthy people take them? Researchers now suggest that the impact of fish oil supplements on disease progression varies between healthy individuals and those with pre-existing cardiovascular diseases.

While fish oil supplements may slow disease progression and lower the risk of death in people with a history of cardiovascular diseases, they might increase the risk of first-time heart disease and stroke among healthy individuals, according to a study published in BMJ Medicine.

The research team made the findings after evaluating the links between the use of fish oil supplements in people without any cardiovascular diseases and the new incidence of atrial fibrillation, heart attack, stroke, heart failure, and death.

Based on a database of 415,737 people from a UK Biobank study, the researchers estimated the role of these supplements in cardiovascular disease progression from good heart health to atrial fibrillation, to heart attacks and death.

The participants were surveyed between 2006 and 2010 to get information on their dietary intake of oily and non-oily fish and fish oil supplements. Their health records were followed up till the end of March 2021 or death, whichever came first.

Of the total participants, one-third reported using fish oil supplements regularly. After an average follow-up of 12 years, 18,367 participants developed atrial fibrillation, 22,636 suffered a heart attack, stroke, or heart failure, and 22,140 died.

In individuals without any cardiovascular disease at the start of the study, regular use of fish oil supplements elevated the risk of atrial fibrillation by 13% and the risk of stroke by 5%. However, for those with cardiovascular disease at the start, regular use of fish oil supplements was associated with a 15% reduced risk of progressing from atrial fibrillation to a heart attack, and a 9% lower risk of progressing from heart failure to death.

"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)," the news release stated.

There are certain limitations of the study. It has not taken into account the dose or formulation of the fish oil supplements. And since most of the participants were white, the results may not be generalizable to other ethnicities.