Adapted from the NCI Cancer Bulletin.
An analysis of numerous, large population cohort studies did not detect evidence of a significant link between dietary intake of omega-3 fatty acids (found in fish) and the incidence of several major cancer types, according to a review study published in the January 25, 2006, issue of the Journal of the American Medical Association (see the journal abstract).
The reviewers analyzed 38 articles covering 20 population cohorts that included more than 700,000 individuals. The participants were studied for the effects of consuming omega-3 - either in fish, dietary supplements, or both - on the incidence of 11 different types of cancer, although more than half of the reports were for either breast, colorectal, or prostate cancers.
The combined studies provided 65 estimates of associations between omega-3 and cancer incidence, but "only 10 were statistically significant," reported the researchers led by Dr. Catherine H. MacLean with RAND Health. Significant associations between omega-3 fatty acid consumption and cancer risk were reported for breast, colorectal, lung, prostate, and skin cancers. "However, for breast, lung, and prostate cancer, there were significant associations for both increased risk and decreased risk and far more estimates that did not demonstrate any association," the researchers noted.
Across the cohorts, no trend was found linking omega-3 fatty acids with a reduced overall cancer risk. "Likewise, there is little to suggest that omega-3 fatty acids reduce the risk of any single type of cancer," the authors wrote.