Selenium

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Selenium may help relieve depression. Low levels of Selenium are associated with heart disease, HIV, miscarriage and female and male infertility. Learn about the usage, dosage, side-effects of Selenium.

Also Known As: selenite, selenomethionine

Overview

Selenium is an essential mineral found in trace amounts in the human body. It works as an antioxidant, especially when combined with vitamin E, by scavenging damaging particles in the body known as free radicals. These particles occur naturally in the body but can damage cell membranes, interact with genetic material, and possibly contribute to the aging process as well as the development of a number of conditions including heart disease and cancer. Antioxidants such as selenium can neutralize free radicals and may reduce or even help prevent some of the damage they cause.

Selenium is needed for the proper functioning of the immune system and for the production of prostaglandins (substances that affect blood pressure and inflammation in the body). Low levels of selenium may worsen atherosclerosis (plaque buildup in arteries which can lead to heart attack and/or stroke) and can lead to premature aging. Selenium deficiencies have also been linked with certain types of cancer.

Many of the benefits of selenium are related to its role in the production of the enzyme glutathione peroxidase. This enzyme is responsible for detoxification in the body. Chronic exposure to environmental toxins, including chemotherapy drugs, radiation and other toxic medicines, increases the requirement for selenium.

Cigarette smokers have lower levels of selenium. There are several reasons for this. Tobacco decreases absorption of selenium in the digestive tract. In addition, many smokers have poor dietary habits and eat fewer foods containing selenium. Alcohol also lowers selenium levels.

Uses

Heart Disease
Low blood levels of selenium can contribute to heart failure. Selenium deficiencies have been shown to worsen atherosclerosis (plaque build up in arteries which can lead to heart attack and/or stroke). It is not known, however, whether selenium supplementation can prevent development or progression of atherosclerosis. Plus, some researchers are concerned that selenium supplements may minimize the benefits of cholesterol lowering drugs.

Cancer
Several animal and human studies have suggested that selenium may protect against the development of colon cancer. Higher cancer rates have been observed in areas where the level of selenium in the soil is low. At least one study has also found that selenium may reduce the risk of death from colon cancer.

Similarly, population based trials suggest that people who eat a diet rich in antioxidants, including selenium, may reduce their risk of prostate cancer. The National Institutes of Health (NIH) is currently sponsoring a large clinical trial, with projections of over 32,000 male participants, to evaluate whether use of selenium and vitamin E helps prevent prostate cancer.

In another study, over 1,300 people with skin cancer were randomly assigned to receive either selenium 200 mcg per day or placebo for at least three years. The researchers found that people who were not taking selenium were more likely to develop lung, prostate, or colon cancers than those who did take the supplement. Plus, an animal study found that selenomethionine (an active breakdown product of selenium) may reduce the spread of melanoma cells in mice. The authors of this study suggest that selenomethionine may prove to be an appropriate addition to the standard treatment for melanoma.

More research is needed to evaluate the use of selenium in preventing and treating the types of cancers discussed in this section. Any potential relationship between selenium supplements and other types of cancer, such as breast and cervical, have not been thoroughly evaluated in studies. Use of selenium supplements in conjunction with other antioxidants (including vitamin C, vitamin E, beta-carotene, and coenzyme Q10) and essential fatty acids, may reduce cancer spread and lessen death rate in women with breast cancer. However, this benefit cannot be attributed to selenium alone.