Chicago – Fish oil, seen as beneficial for reducing heart-disease risks, probably doesn’t help prevent cancer, according to a review of studies involving more than 700,000 patients.
Researchers examined data from 38 studies that tracked patients for up to 30 years and said most showed no cancer protection from omega-3 fatty acids.
A few studies found some risk reduction for cancers of the breast, prostate and lung, but those studies were relatively small and not definitive, said Dr. Catherine MacLean, the lead author of the study, which appears in today’s Journal of the American Medical Association. She is researcher at the Rand Corp. and Greater Los Angeles Veterans Affairs Healthcare System.
“It doesn’t mean that omega-3 fatty acids don’t have other health benefits – it’s just that reducing cancer risk isn’t one of them,” MacLean said.
Diet is known to play a role in cancer, and the researchers evaluated observational studies, which provide mostly circumstantial evidence. The reviewed studies examined the effects of fish oil – in both pill form and as food – on 11 kinds of cancer, mostly tumors of the breast, colon, lung or prostate.
The 38 studies are too heterogeneous – involving different population groups and different levels of fish-oil consumption – to provide a definitive conclusion about whether fish oil reduces cancer risks, said Julie Buring, a chronic-disease researcher at Harvard’s Brigham and Women’s Hospital, who was not involved in the study.
“It doesn’t tell us it’s unlikely or likely,” Buring said. “… Right now we don’t know.”
