It’s been credited with everything from relieving joint pain to good heart and brain health.
Fish oil, a rich source of omega-3 fatty acids, is often recommended as a dietary preventative to prevent the development of cardiovascular diseases.
But new research suggests that taking the popular supplement could actually increase the chances of heart disease and stroke in healthy adults, while reducing the risk in those with a history of the disease.
The study, which involved more than 415,000 Britons, looked at associations between fish oil supplements and new cases of atrial fibrillation, heart attack, stroke and heart failure leading to death.
They evaluated the potential of these supplements on the risk of moving from good heart health to the secondary stage of atrial fibrillation, the third stage of major cardiovascular events such as heart attack and death.
Nearly a third (130,365) of participants, ages 40 to 69, said they regularly used fish oil supplements, including a large number of older, white people and women.
Fish oil is credited with everything from relieving joint pain to good heart and brain health.
In fact, the popular supplements may increase the chances of heart disease and stroke in healthy adults.
Alcohol intake and the proportion of fatty and non-fatty fish consumed were also higher, while the proportions of current smokers and those living in deprived areas were lower.
During a follow-up 12 years later, 18,367 had developed atrial fibrillation with abnormal heart rhythm, 22,636 had suffered a heart attack, stroke or heart failure, and 22,140 had died.
Of those who developed heart failure, 2,436 died, along with 2,088 who suffered a stroke and 2,098 after a heart attack, according to findings published in BMJ Medicine.
The findings indicated that regular use of fish oil supplements had different roles in cardiovascular health, disease progression and death.
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 having a 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 nine percent.
The risk of going 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 consumers.
Meanwhile, the protective effect of these supplements on the transition from good health to death was greatest in men (7 percent lower risk) and older participants (11 percent lower risk).
Led by Sun Yat-Sen University, China, the researchers admit limitations to the study, including the fact that the dosage and formulation of the fish oil were not recorded, which experts say could be key to the results.
However, they conclude: “Regular use of fish oil supplements could play different roles in the progression of cardiovascular disease.”
“Further studies are needed to determine the precise mechanisms for the development and prognosis of cardiovascular diseases with regular use of fish oil supplements.”
It is not the first study to reach such conclusions with a 2018 Cochrane review of research that compared 79 trials and found there was “little or no difference in the risk of cardiovascular events, coronary deaths, coronary heart disease events, stroke or cardiac irregularities.