Glutathione peroxidase, an enzyme that protects the cell from lipid oxidation and functions with (and can substitute for) in vivo vitamin E, contains selenium. Selenium is associated with the degradation of intracellular peroxides and the oxidation of glutathione. Selenium is absorbed principally in the duodenum (80%) and is dependent on a number of variables. In particular, sulfurated amino acids can increase absorption significantly. Selenium is principally excreted in the urine, with extraordinary fecal losses occurring in the setting of bowel compromise. Total body content of selenium varies according to the relative amount present in the soil. The highest concentrations are found in the kidney, followed by the liver, muscle, and skin. Muscle contains almost half the total body selenium content. Myositis with concurrent complaints of muscle pain coupled with cardiomyopathy and abnormal elevations of creatine phosphokinase serum concentrations provide evidence for empiric selenium supplementation.
Selenium prevents the occurrence of Keshan disease, a juvenile cardiomyo-pathy precipitated by very low dietary selenium intake. The disease is characterized by congestive heart failure with moderate to severe enlargement of the heart and facial edema, which may involve a predisposing condition not yet clarified.
Inadequate selenium nutriture has additionally been linked to Kashin-Beck disease, an endemic osteoarthritis.88
Selenium appears to be capable of selectively regulating the generation of functional lymphocyte subsets in vitro. Such selective regulation could explain the published effects of selenium on immunity and would be consistent with a role for immunity in the observed reduction of cancer incidence associated with elevated selenium intake.89
Was this article helpful?