Healthnotes Newswire (December 6, 2001)—New evidence in the Journal of Agricultural and Food Chemistry indicates that consuming broccoli specially grown to contain large amounts of selenium may prevent the development of breast and colon cancer.¹ The beneficial effect of high-selenium broccoli was above and beyond the known anticancer effect of broccoli. Moreover, the selenium incorporated into broccoli by a specific growing technique appeared to be more effective at fighting cancer than the inorganic selenium commonly found in selenium supplements.

The researchers treated rats with a chemical cancer-causing agent (carcinogen) in order to induce breast cancer. The rats were fed either (1) a standard diet, (2) the standard diet supplemented with broccoli, or (3) the standard diet supplemented with broccoli that was grown in a high-selenium environment and contained 2,000 times as much selenium as regular broccoli. The regular broccoli did not contribute a significant amount of selenium to the diet, whereas the diet supplemented with high-selenium broccoli increased the selenium content of the diet 30-fold. The incidences of breast tumors in rats fed regular broccoli and high-selenium broccoli were reduced by 37% and 59%, respectively, compared with the incidence in rats given the standard diet. These findings demonstrate that selenium supplementation can reduce the incidence of breast cancer. However, since the low-selenium broccoli also prevented breast cancer, other compounds in broccoli may also be protective. One such compound is indole-3-carbinol, which has been shown in numerous studies to have anticancer effects.^{2 3}

In the second part of the study, rats were treated with another chemical that promotes the development of colon cancer. Selenium, in the form of high-selenium broccoli, high-selenium broccoli sprouts, or inorganic selenium (sodium selenite) all reduced the incidence of precancerous changes in the colon. However, the food-derived selenium was significantly more effective than sodium selenite.

Although favorable results in animal studies do not always translate into benefits for humans, one controlled study found that 200 mcg of supplemental selenium per day (from high-selenium yeast) lowered the incidence of prostate, lung, and colon cancer by 63%, 46%, and 58%, respectively, and reduced total cancer deaths by 50%.⁴ Significantly, the study demonstrated that taking selenium as a nutritional supplement is an effective means to reduce the risk of developing some cancers. Physicians and nutritionists often recommend 200 mcg of daily supplemental selenium to get the cancer-protecting benefits.

It should be noted that some of the selenium present in high-selenium yeast and other foods (including the broccoli used in the present study) has a different chemical structure than that of most selenium supplements. Although the selenium sold in supplement form has been shown to have anticancer activity, the results of this study suggest that food-derived selenium may be even more effective.

In addition to broccoli, studies have found other nutritional supplements and herbs to be effective at lowering risk of cancer. Vitamins C and E, beta-carotene, folic acid, flaxseed oil, and soy, as well as herbs such as garlic and green tea, may have specific anticancer benefits. It is always advisable to consult with a nutritionally-oriented healthcare practitioner concerning dietary recommendations and nutritional supplements.