Daily fish oil may raise risk of heart disease in healthy people

A study of more than 400,000 people with a healthy heart found daily fish oil supplements were associated with a 13 per cent heightened chance of actually developing health issues.

Regular use of fish oil supplements could have a differential role in the progression of cardiovascular disease, researchers said. Picture: Getty

Taking a daily fish oil supplement could raise the risk of heart disease and stroke in healthy people, researchers have found.

A study of more than 400,000 people for an average of 12 years found that those who took a fish oil supplement regularly and began with a healthy heart had a 13 per cent heightened risk of developing atrial fibrillation, or an irregular heartbeat, a sign of heart disease. But for those with poor heart health, such supplements slowed the progression of cardiovascular disease and lowered the risk of death.

Omega-3 fatty acids, a key element in the supplements, are unsaturated fats, found in oily fish such as sardines, tuna and mackerel as well as in nuts and seeds. They are thought to lower blood pressure, prevent clots and improve circulation.

It is estimated from the UK Biobank dataset that 31 per cent of people in the UK regularly take a fish oil supplement.

The results of the research, published in BMJ Medicine, suggest that fish oil supplements may affect people differently, depending on the health of their heart. For those with no known cardiovascular disease at the start of the monitoring, regular use of supplements was associated with a 5 per cent raised risk of having a stroke.

“We found that regular use of fish oil supplements could have a differential role in the progression of cardiovascular disease,” the researchers said.

The team from Sun Yat-sen University, in Guangzhou, China, looked at 415,737 people recruited by the UK Biobank between 2006 and 2010 and tracked their health until March 2021 or death. Just under a third of them took fish oil supplements regularly.

Of all the participants, more than 18,000 developed atrial fibrillation and more than 22,000 had heart attacks. Of those who started with good heart health, 3,500 developed heart failure or had a heart attack and more than 1,000 had a stroke.

The study was observational, and the researchers said they could not determine if fish oils caused cardiovascular problems in healthy people or if another factor caused the association.

Previous research has shown that in countries where people eat more oily fish, such as Greenland and Japan, fewer people have heart disease than in countries where people eat little oily fish, such as the UK. A 2022 study found that adults who ate 2g to 3g of omega-3 fatty acids a day had lower blood pressure and so a lower risk of heart attack.

The Times