ROLE OF SELENIUM

Oxidative damage caused by free radicals results in many detrimental conditions including chronic diseases. Selenium, an essential trace mineral that is part of antioxidant enzymes, protects cells against the effects of free radicals. (1) Adequate selenium status can protect molecules against oxidative and peroxidative damage common in PLWHIV. (2) Selenium is also essential for normal functioning of the body's immune system and thyroid gland.

Physiologically, selenium (Se) functions in the form of selenoproteins, incorporating selenium as selenocysteine. Numerous selenoproteins have been identified (Table 1). The total number in humans and higher animals may be as high as 30-50 units. (3, 4) Selenium's role in the enzyme glutathione peroxidase was discovered in 1973. (5) Unlike zinc, selenium homeostasis is not regulated by absorption. (4) Proteins containing selenomethionine are digested in the human body and absorbed with the selenomethionine intact. Selenomethionine is metabolized analogously to selenocysteine or can be incorporated into selenoproteins that serve as unregulated storage forms of selenium. (5)

SELENIUM AND THE IMMUNE SYSTEM

Selenium is vital to cell-mediated immunity and B-cell function. (5) The body also needs adequate levels of selenium for T-cells, to function properly. Various researchers who studied the relationship of trace elements and the immune system associated abnormal copper, selenium or zinc levels with immune dysfunction. (6-10) Along with zinc, HIV uses selenium in viral proteins, creating a complex set of interactions between nutrient levels, host requirements and viral utilization. (11) Taylor disclosed that the use of zinc and selenium by the HIV virus might at least lead to a localized intracellular depletion of these minerals. Although a deficiency of selenium appears to be associated with HIV disease progression, selenium supplementation inhibits the virus and may slow progression. (2)