LONDON, May 28 — Contrary to popular belief, fish oil may not always be good for your health, especially your cardiovascular health. A new study even reveals that regular use of fish oil supplements may increase the risk of heart disease and stroke. So when should — and shouldn’t — you take fish oil supplements?

Old-timers will know — and remember — that cod liver oil was once considered a benchmark nutritional supplement given to schoolchildren to make them stronger. Several decades later, the benefits of fish oil are still very much on the agenda. Particularly rich in omega-3 fatty acids, it is said to protect the heart, reduce bad cholesterol and even prevent certain cognitive disorders. These benefits have been highlighted by numerous scientific studies, but new research suggests that things might not be so clear-cut. In fact, a team of researchers has revealed that fish oil-based supplements may not always be beneficial to health.

It all depends on how healthy you are when you take these supplements. Based on data from 415,737 participants aged between 40 and 69, and from the UK Biobank study, the research reveals that regular consumption of this type of supplement could actually increase the risk of heart disease and stroke in people in good cardiovascular health. This important finding does not prevent the authors of the study from pointing out that these same supplements could, on the other hand, slow the progression of existing poor cardiovascular health, and even reduce the risk of death for those individuals.

To reach these conclusions, the researchers analysed the participants’ usual consumption of fatty and non-fatty fish, as well as fish oil-based dietary supplements. They also assessed potential associations between this supplementation and new cases of atrial fibrillation, heart attack, stroke, heart failure and all-cause death in people with no known cardiovascular disease. Then, they set out to assess whether or not this kind of supplementation could worsen the heart health of participants, who were followed for an average of 12 years.

Benefits, but not for everyone

Published in the BMJ Medicine journal, this research found that fish oil supplements did not have the same impact on people’s cardiovascular health. In other words, regular use of this type of supplement did not have the same impact on cardiovascular health and the progression of cardiovascular disease in all participants. In detail, the researchers found an association between regular intake of fish oil supplements and an increased risk of atrial fibrillation (+13 per cent) or stroke (+5 per cent) in those in good cardiovascular health at the start of the study.

But at the same time, they found that the same supplementation reduced the risk of progressing from atrial fibrillation to heart attack by 15 per cent, and the risk of progressing from heart failure to death by 9 per cent in people with cardiovascular disease at the start of the monitoring period. This may mean, as the scientists point out, that fish oil-based supplements could be beneficial in slowing the progression of cardiovascular disease in affected individuals. It should be noted, however, that factors such as gender, age, smoking and consumption of non-fatty fish significantly altered the associations observed.

"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,” the study authors say in a news release. — ETX Studio