Researchers in the U.S. have found in a comprehensive review of numerous studies, that there is little evidence to support the belief that the consumption of omega-3 fatty acids reduces risk of cancer.
The researchers at RAND Health and the Greater Los Angeles VA Healthcare System reviewed some 38 studies published between 1966 and 2005 on omega-3 fatty acids, found in some fish and certain vegetables and also sold as dietary supplements.
Previous studies have suggested that people who consume diets rich in omega-3 fatty acids may experience a lower prevalence of some types of cancer.
In many small trials they have tried to assess the effects of omega-3 fatty acids on cancer treatment by adding omega-3 fatty acid to the diet either as omega-3 fatty acid-rich foods or as dietary supplements.
As a result a number of omega-3 fatty acid - containing dietary supplements have appeared on the market claiming to protect against the development of a variety of conditions including cancer, despite studies reporting mixed results.
Catherine H. MacLean, M.D., Ph.D., of RAND Health, Santa Monica, Calif., and colleagues independently abstracted detailed data about the incidence of cancer, the type of cancer, the number and characteristics of the patients, details on the exposure to omega-3 fatty acids, and the elapsed time between the intervention and outcome measurements.
MacLean says there have been few studies that showed a reduced risk of cancer from consuming the fatty acids, but they found even more studies that showed no decrease in cancer risk and even a few that suggested a higher risk.
The team concluded that there is no relationship between omega-3 fatty acids and lower rates of any types of cancer.
The study was published in the Journal of the American Medical Association.