Selenium Health Article

Internal medicine

Selenium is most widely recognized as a substance that speeds up the metabolism of fatty acids and works together with vitamin E (tocopherol) as an antioxidant. Antioxidants are organic substances that are able to counteract the damage done to human tissue by oxidation (the breakdown of fatty acids). Selenium's antioxidant properties have been studied with respect to several diseases and disorders. In addition to its antioxidant properties, selenium also appears to work as an anti-inflammatory agent in certain disorders.

CARDIOVASCULAR DISEASES. Low levels of selenium have been associated with high risk of heart attacks and strokes. It is thought that the antioxidant properties of selenium can help prevent atherosclerosis (narrowing and hardening of the arteries) by decreasing the formation of fatty deposits in the arteries. It does so by soothing the inflamed arterial walls and binding the free radicals that damage the tissues lining the arteries. Other studies indicate that selenium reduces the symptoms of angina pectoris.

CATARACTS. Cataracts in the eye contain only one-sixth as much selenium as normal lens tissue. The healthy lens requires adequate levels of three antioxidant enzymes: superoxide dismutase, catalase, and glutathione peroxidase. Glutathione peroxidase in the human eye is dependent on selenium, which suggests that a selenium deficiency speeds up the progression of cataracts.

CANCER. Low dietary levels of selenium have been associated with an increased incidence of cancer. Cancers of the respiratory system and the gastrointestinal tract seem to be especially sensitive to the level of selenium in the body. In a recent study, patients with histories of skin cancer were given 200 g of selenium per day. Results indicated that the patients had a reduced incidence of rectal, prostate, and lung cancers as well as a lower rate of mortality from all cancers. In addition, cervical dysplasias (abnormal growths of tissue) in women are associated with low levels of selenium in the patient's diet. In animal studies, as little as 1–4 parts per million of selenium added to the water or food supply is associated with a decreased incidence of cancer. It is not yet known, however, exactly how selenium protects against cancer. Some researchers believe that it may prevent mutations or decrease the rate of cell division, particularly on the outer surfaces of the body. A recent study of the effects of a selenium compound on mammary tissue indicates that selenium may inhibit the growth of tumors in deeper layers of tissue, not just cancers arising from the epithelium.

As of 2002, selenium is being studied as a possible chemopreventive for prostate cancer. The researchers hope to learn more about the mechanisms by which selenium slows the progress of an established cancer as well as discover a preventive strategy that makes use of selenium.

PERIODONTAL DISEASE. Selenium appears to speed up the healing of fragile gum tissue as well as opposing the actions of free radicals, which are extremely damaging to gum tissue.

RHEUMATOID ARTHRITIS. Selenium may be useful for treating several autoimmune diseases, especially lupus and rheumatoid arthritis (RA). It has been discovered that patients suffering from RA have low selenium levels. Selenium is necessary for production of the enzyme glutathione peroxidase, which reduces the production of inflammatory substances in the body (prostaglandins and leukotrienes) as well as opposing free radicals. Although supplemental selenium by itself has not been shown to cause improvement in RA, selenium taken together with vitamin E appears to have measurable positive results.

OSTEOARTHRITIS. Recent research in Germany indicates that selenium is beneficial in the prevention and treatment of osteoarthritis (OA), particularly OA resulting from physical wear and tear or structural problems in the patient's joints. Selenium supplements are even more effective when given together with vitamins in treating OA.

Preparations

Selenium is available in topical preparations and as a dietary supplement.

External preparations

Selenium sulfide for the treatment of dandruff is available as over-the-counter (OTC) scalp preparations or shampoo containing 1% or 2.5% solutions of the drug. A topical 2.5% solution of selenium sulfide is available for the treatment of tinea versicolor. Common trade names include Exsel™, Selsun™, and Selsun Blue™.

Dietary supplements

Selenium is widely available in vitamin/mineral dietary supplements and in nutritional antioxidant formulas. Although the average diet supplies enough selenium, some naturopaths recommend daily supplements of 100–200 g for adults and 30–150 g for children. Sexually active males are advised to take higher doses. Some naturopaths recommend taking selenium together with vitamin E on the grounds that their combined effect is greater than the sum of their individual effects. There are at present no definitive studies on the positive effects on health of selenium taken as a dietary supplement.