Selenium, Omega-3s May Stave Off Colorectal Cancer

Studies find benefits, but others question validity of the link

Certain dietary supplements appear to affect the development of colorectal cancer or its recurrence according to the results of two new studies.

In one study, researchers 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, consumption of a dietary supplement containing selenium was found to reduce the chances of having polyps recur by a similar amount.

This marks yet another study in which supplementation or diets high in Omega 3 fatty acids are showing benefits in health.

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.

Extrapolating this data forward 15 years into the future, it is suggested that 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.

Selenium is found in soil, and human consumption comes by eating plants that have absorbed the nutrient or fish or animals that have eaten plants as part of their diet.  Earlier research has indicated that selenium can inhibit cell proliferation in the colon and rectum.

Once again, though the findings are interesting, researchers say that it's mpossible to tell if the benefit was attributable to the selenium or to the other vitamins and minerals included in the supplement, either alone or in combination.

In the omega-3 study, U.S. researchers surveyed 1,509 whites and 369 blacks about their dietary habits in the past year. About half of the participants had colorectal cancer.

Among the white participants, those whose diets were in the highest fourth of omega-3 fatty acid consumption were 39 percent less likely to have colorectal cancer than those in the lowest fourth. However, for reasons the authors said they did not know, no association was noted between omega-3s and a reduction of colorectal cancer risk among black participants. The disease occurs at a higher rate among blacks than whites.

Finally, some commitment to a finding.

One of the researchers in the Omega 3 study notes that their finding clearly supports the evidence from previous experimental and clinical studies showing that long-chain omega-3 fatty acids inhibit tumor growth.

Researchers purport that the research supports boosting omega-3 intake through diet or perhaps by taking an omega-3 supplement. Omega-3 fatty acids are found in fish, especially oily fish such as salmon, mackerel, herring, anchovies, sardines and tuna. Plant-based sources include flax and flaxseed oil, Brussels sprouts, soybeans and soybean oil, canola oil, spinach, walnuts and kiwi.

Previous studies have suggested that omega-3 fatty acids act as anti-inflammatory agents and help prevent cancer.

In our clinic, we have seen dramatic reductions in people with neck pain and headaches associated with neck pain when Omega 3's are added to the patient's diet.

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