Who benefits from fish oil supplements?
Two significant studies have given long-awaited answers on who does and who does not benefit from taking fish oil or vitamin D supplements.
One study found that a purified, prescription-strength fish oil, icosapent ethyl, slashed heart problems and heart-related deaths among people with high triglycerides and other heart risks.
Doctors said the results could suggest a new treatment option for hundreds of thousands of patients such as these.
But another study in healthy people found no clear benefit from a lower dose of fish oil, an amount that's common in dietary supplements.
A separate test of vitamin D supplements found they also did not lower heart or cancer risks.
"Those who peddle it promote it as good for everything, [but in this test, vitamin D] showed a big nothing," said Dr James Stein, a heart specialist at the University of Wisconsin-Madison. Dr Stein had no role in the studies or ties to the companies involved.
Results of the three studies were revealed at an American Heart Association conference in Chicago and published by the New England Journal of Medicine.