Go Fish! Types High in Fatty Acids May Prevent Prostate Cancer
Herring, Mackerel, and Salmon Recommended
Mark Moran, MPH
WebMD Medical News
June 1, 2001 -- Fish that are high in fatty acids, such as mackerel, salmon or herring, may help prevent prostate cancer, according to a large study of Swedish men in the June edition of the British medical journal The Lancet.
"The main message is to eat more fatty fish," says co-author Alicja Wolk, DMSC. "Eating fatty fish reduces risk of prostate cancer by about 70%, compared to not eating it, and reduces the risk for death from the disease by about 50%." Wolk is a professor of nutrition and epidemiology at the Karolinska Institute in Stockholm, Sweden.
The study was an epidemiologic investigation, which looks at the occurrence of disease in a large population of people. The researchers followed 6,272 Swedish male twins for 30 years, examining lifestyle factors -- including diet -- and drawing associations with the risk for prostate cancer.
They found that men who consumed moderate to high amounts of fatty fish were two-to-three times less likely to develop prostate cancer than men who did not, according to the report.
Because all the men in the study were twin pairs, the researchers were able to adjust their findings to account for genetic factors. And the findings remained consistent despite other potential risk factors for prostate cancer, such as smoking and alcohol use.
The bottom line: fatty fish consumption is a powerful determinant of disease, Wolk says.
Wolk says the study contributes to accumulating evidence that the fatty acids present in fish protect against prostate cancer. Previous studies measuring the amount of fatty acids in blood have indicated that men with higher concentrations were less likely to get prostate cancer, she says.
She notes that in addition to the fatty acids, fish are a rich source of vitamins and selenium, a mineral believed to have "antioxidant" effects, preventing the oxidation of cells in the progression of cancer. "So the beneficial effects of fish may be due to a combination of all of these factors," Wolk tells WebMD.
And Wolk adds that there is accumulating evidence that the fatty oils in fish may also be good for preventing heart disease and stroke.
Urologist William Catalona, MD, who reviewed the report for WebMD, says the study offers "credible evidence" of the role of fatty fish in preventing prostate cancer.
"There is a lot of evidence that dietary factors can influence the development and progression of prostate cancer," he says. "The current view is that there are probably a handful of genes that can predispose a person to prostate cancer. But if you have an inherited susceptibility, it doesn't mean you will get it unless there is a permissive environment. A lot of the environment can be influenced by diet." Catalona is professor of urology at Washington University School of Medicine in St. Louis.
He notes that the purpose of epidemiologic studies is to raise hypotheses. More conclusive proof would be extraordinarily difficult to come by, requiring a long-term experiment directly comparing occurrence of disease in men who consumed fish and those who did not.
"As epidemiologic studies go, this provides fairly convincing evidence that, for whatever reason, men who consume larger amounts of fish are less likely to get prostate cancer," Catalona says.
And the study adds to a list of other foods that may diminish risk for prostate cancer, including green tea, tomatoes and other lycopene-containing fruits, as well as vitamin supplements, and selenium.
Lycopene is part of a family of pigments, called carotenoids, which occur naturally in fruits and vegetables.
"Patients who have prostate cancer or a family history are always asking doctors what they can do to reduce their risk," Catalona says. "Eating salmon and other fatty fish can be added to the list of foods where there is some evidence to support a beneficial effect."