Selenium, Omega-3s May Stave Off Colorectal Cancer

Dec. 9 -- TUESDAY, Dec. 8 (HealthDay News) -- Certain dietary supplements appear to affect the development of colorectal cancer or its recurrence, two new studies suggest.

In one study, researchers from the U.S. National Institute for Environmental Health Sciences found that eating a diet high in omega-3 fatty acids cut the risk of developing colorectal cancer by nearly 40 percent. In the other study, from cancer researchers in Italy, consumption of a dietary supplement containing selenium was found to reduce the chances of having polyps recur by a similar amount.

Both studies were to be presented Dec. 7 in Houston at a conference on cancer prevention sponsored by the American Association for Cancer Research.

In the selenium study, 411 people, 25 to 75 years old, who'd had one or more colorectal polyps removed took either a supplement or a placebo. The supplement, described as an antioxidant compound, contained 200 micrograms of selenomethionnine (a combination of selenium and methionnine), 30 milligrams of zinc, 6,000 international units of vitamin A, 180 milligrams of vitamin C and 30 milligrams of vitamin E.

Participants had a colonoscopy one year, three years and five years after starting the regimen.

Polyps recurred in 4.2 percent of those taking the supplement, compared with 7.2 percent of the placebo group. Overall, the study found, people taking the supplement had about a 40 percent reduction in risk for a return of polyps.

The researchers estimated that, after 15 years, about 48 percent of those taking the supplement would still be free of polyps, versus about 30 percent of those not taking the supplement.

Polyps, or adenoma, are benign growths on the large bowel. Though only a small proportion progress to become cancer, about 70 to 80 percent of colorectal cancer cases begin as polyps, according to the American Association for Cancer Research. About one in four people, most older than 60, will have at least one adenoma.