Natural Health

Selenium - Little Known, but Important

By: Jennifer Newell
Published: Saturday, 22 March 2008
Brazil nuts

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Studies have suggested a link between cancer and selenium deficiency, but said research has also shown that selenium may help prevent cancer by acting as an antioxidant or by enhancing the immune system. Low-dose supplements of the nutrient showed a reduction in the incidence of cancer in nearly one-third of subjects, and males seem to be more responsive to the study than females. While those studies are ongoing, selenium has been proven to help chemotherapy treatments by reducing the toxicity of the accompanying drugs and preventing the body’s resistance to those drugs.

Selenium is a nonmetal chemical element related to sulfur and tellurium. While large amounts are toxic, miniscule amounts are necessary for cellular function as the center of certain enzymes. Trace elements in humans allow for a natural defense against toxins, and the regulation of thyroid hormone metabolism and cells’ redox state.

Selenium is taken into the body through the food chain via plant proteins. Foods containing the nutrient are nuts, cereals, meats, fish, and eggs. The highest levels of selenium are found in Brazil nuts, and slightly lower doses are in kidney, crab, and lobster. The recommended dietary allowance for adults is 55 micrograms per day but can range from 50 to 200 in the average person, and a healthy diet provides such intake.

Deficiency of selenium can cause symptoms of hypothyroidism, cardiovascular disease, and can sometimes occur in people with severely compromised intestinal function. Keshan disease and Kashin-Beck disease can result from extreme deficiency, thus weakening the heart and cartilage tissue, but such rare cases are mainly found in China where the soil lacks proper amounts of selenium. On the other hand, excess amounts of the nutrient can cause gastrointestinal disorders and neurological damage, and in severe cases, cirrhosis of the liver and pulmonary edema.

Other research has indicated that low selenium levels in AIDS patients are connected to decreased immune cell count and increased progression of the disease. While supplements have been shown to reduce the symptoms of infected patients, they have not proven helpful in the reduction of initial infection.

Men taking five times the recommended daily allowance of selenium reported weight gain. Women who are pregnant or nursing are advised to avoid selenium levels exceeding 60 to 70 micrograms daily.

The selenium content of soil determines the content of selenium in food. Some areas of the US have extremely high selenium levels in the soil. In most countries, the major dietary sources of selenium are from plant foods.