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Supplement Savvy For Cancer: Selenium

By Jill Place, MA, RD

What It Is . . .

Selenium is an essential mineral in human nutrition. Selenium enters the plants that you eat from the soil. It's very difficult to judge the amount of Selenium in plants as some areas where food is grown have a lot of Selenium in the soil while others don't. So it might be a good bet to supplement your diet with Selenium if the soil in your area is Selenium-depleted.

What It Does . . .

Selenium has been widely studied for its cancer preventive effects. Selenium:

may protect against a wide variety of tumors including lung, gastric, colorectal, prostate, breast, liver, and skin cancers.

may reduce overall cancer risk by as much as 52%.

might be essential for healthy immune function because it helps produce more T-cells, stimulates the production of antibodies, and may decrease age-related slowing of your immune response.

helps produce glutathione peroxidase, an important enzyme that keeps fats from oxidizing and causing free radicals. Free radicals are atoms with an odd number of electrons. These electrons want to pair up with other electrons. So they run around trying to find another electron to marry. While they're running around, they can cause damage to DNA or cell membranes. This damage may cause cancer. Antioxidants marry with free radicals and stop them from doing damage.

works well with other minerals like Copper and Zinc that stop free radicals with antioxidant enzymes like glutathione peroxidase and superoxide dismutase.

works well with primary antioxidants like Vitamin E and Vitamin C, that directly marry with free radicals.

may stop angiogenesis, or the formation of new blood vessels that feed tumors so that they can grow.

What To Do . . .

Even though Selenium seems to be a "must-take" for your supplement list, there's a lot of disagreement as to whether Selenium and other antioxidants are appropriate to take during treatment. Many professionals agree that antioxidants may protect cancer cells as well as normal cells during chemotherapy and radiation and make treatment less effective. At this point, there aren't enough human studies to show that taking antioxidants is safe during treatment. So it might be wise to stop taking Selenium as well as other antioxidants and multivitamins one to two weeks before treatment and resume taking them one or two weeks after treatment.

Selenium could be a "must-take", however, for your cancer prevention supplement list after treatment. Selenium can be found in most multivitamins. Since Selenium works well when combined with other nutrients, a multivitamin might be a good idea if you want to take supplements. You might want to ask your dietitian or Supplement Savvy Specialist to help you choose a good form and an appropriate dosage of Selenium.

What To Watch Out For . . .

There are no known interactions with Selenium and drugs. Pregnant women and nursing mothers should avoid taking too much.

Selenium may enhance the absorption of Iodine and Vitamin E. Prolonged doses of 1,000 mcg (1 milligram) or greater may possibly cause toxicity, brittleness of hair and nails, hair loss, skin rash, bad breath, fatigue, irritability, and nausea and vomiting.

Ask your dietitian or Supplement Savvy Specialist about how much Selenium would be a good dose for you.

© Copyright 2002 Jill Place, MA, RD