To the Editor. —
A recent article by Kok et al1 reports finding lower selenium levels in toenails and erythrocytes of patients with acute myocardial infarction than in those of a matched control group. Other articles have presented similar results in subjects with cancer,2 although studies with negative results also have been reported.
Selenium serves as an oxidant defense in the body, and selenium levels often are equated with oxidant defense status. Thus, finding lower selenium levels in a group of patients with a particular disease often is taken as evidence that the disease process is related to oxidant stress and that selenium deficiency facilitates its development. Most studies of this type ignore what is known about the nature of tissue selenium.
Dietary selenium can be divided into two types. One type, which includes selenocysteine and inorganic forms of the element, is incorporated only into selenoproteins such as
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