Contrary to popular belief, fish oil supplements do not reduce the risk of heart attacks and strokes, a large study has found.
Scientists pooled evidence from 20 studies involving almost 70,000 patients.
They concluded that taking omega-3 fatty acids derived from fish oil had no significant effect on rates of heart attacks, strokes and heart-related deaths.
Previous trials have both supported and rejected the idea that the supplements may protect the heart.
Omega-3 polyunsaturated fatty acids (Pufas) are known to fight inflammation, one of the key processes that contribute to narrowing of the arteries.
Researchers conducting the new study analysed data on 7,044 deaths, 3,993 heart-related deaths, 1,150 sudden deaths, 1,837 heart attacks and 1,490 strokes.
The results, published in the Journal of the American Medical Association, showed no evidence of risk reduction associated with omega-3.
Dr Evangelos Rizos, from the University Hospital of Ioannina, Greece, and colleagues wrote: "In conclusion, omega-3 Pufas are not statistically significantly associated with major cardiovascular outcomes across various patient populations.
"Our findings do not justify the use of omega-3 as a structured intervention in everyday clinical practice, or guidelines supporting dietary omega-3 Pufa administration."