A comprehensive British study has raised concerns that fish oil supplements, taken by millions for their Omega 3 fatty acids, might increase the risk of heart disease and stroke for some individuals. The research, published in BMJ Medicine, analyzed data from 415,737 participants aged 40-69 years from the UK Biobank, tracking their health from 2006-2010 until March 2021.
Key Findings on Cardiovascular Risks
Among participants without known cardiovascular disease at the start, regular fish oil supplement use was associated with a 13% increased risk of developing atrial fibrillation and a 5% increased risk of experiencing a stroke. Nearly one-third (31.5%) of participants reported regular consumption of these supplements, which were more common among older white women.
However, for those already diagnosed with cardiovascular conditions, the supplements appeared beneficial. Regular use was linked to a 15% reduced risk of progression from atrial fibrillation to a heart attack and a 9% reduced risk of progression from heart failure to death.
Expert Reaction from British Heart Foundation
The British Heart Foundation reviewed the study and advised caution. A spokesperson stated: "This research should not be concerning to people who regularly take fish oil supplements, but it's also not a green light to start taking them to prevent heart and circulatory diseases." They emphasized that a balanced diet including oily fish provides essential omega-3 and other nutrients, and recommended the Mediterranean diet for heart health.
Contrasting Evidence from Other Studies
Interestingly, a major international trial called PISCES, published in The New England Journal of Medicine in 2025, found that dialysis patients taking four grams of fish oil daily had a 43% lower risk of serious cardiovascular events, including heart attack, stroke, and cardiac death.
Another recent study indicated that regular fish oil supplement use was linked to a 6% increased risk of serious cardiovascular events in women and non-smokers, while men experienced a 7% reduction in death rates.
Limitations and Further Research Needed
The researchers acknowledged that due to the observational nature of the study, they cannot establish cause and effect. They also lacked information on dosage or supplement types. They concluded: "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."
