Chemoprevention of cancer: selenium.

1. Selenium intake (in the form of selenite, selenate, selenomethionine, etc.) protects the organism against the action of some kinds of carcinogens. 2. People and animals having less Se in their blood are at a higher risk of acquiring cancer than those whose blood contains more of this element. 3. This chemopreventive action is probably due to antioxidant properties of Se, its involvements in the enzyme glutathione peroxidase as well as in the inhibition of enzymes converting carcinogens to their ultimate forms in the cell. 4. An intake of 150-300 micrograms of Se daily is considered to be adequate to protect the human organism without exhibiting the toxic properties of this element.