Cancer and Selenium

Several studies have shown links between cancer and selenium deficiency. A study conducted on the effect of selenium supplementation showed a significantly reduced occurrence of total cancers. Dietary selenium prevents chemically induced carcinogenesis in many rodent studies. Selenium may help prevent cancer by acting as an antioxidant or by enhancing immune activity. Not all studies agree, however, on the cancer-fighting effects of selenium.

One study of naturally occurring levels of selenium in over 60,000 participants did not show a significant correlation between those levels and cancer. One study concluded that low-dose supplementation* resulted in a 31% reduction in the incidence of cancer and a 37% reduction in all cause mortality in males, but did not get a significant result for females. Selenium has been proven to help chemotherapy treatment by enhancing the efficacy of the treatment, reducing the toxicity of chemotherapeutic drugs, and preventing the body's resistance to the drugs. One of the studies showed that in just 72 hours, the efficacy of treatment using chemotherapeutic drugs with selenium yeast is significantly higher than the treatment using the drugs alone. The finding was shown in various cancer cells (breast, lung, small intestine, colon, liver).

In humans, selenium functions as a partner for reduction of antioxidant enzymes. It also plays a role in the functioning of the thyroid gland by participating as a partner for thyroid hormone deiodinases.

Selenium comes from nuts, cereals, meat, fish, and eggs. Brazil nuts are the richest ordinary dietary source (though this is soil-dependent, since the Brazil nut does not require high levels of the element for its own needs). High levels of selenium are found in meats of kidney, crab and lobster, in that order.

*(with 120 mg of ascorbic acid, 30 mg of vitamin E, 6 mg of beta carotene, 100 mg of selenium, and 20 mg of zinc)