Ultratrace Minerals : Selenium

Se is present in ~25 human proteins (selenoproteins) as a constituent of the amino acid selenocysteine, which is derived from serine . Selenoproteins include glutathione peroxidase that oxidizes glutathione in the reduction of hydrogen peroxide, a ROS, to water ; thioredoxin reductase that reduces thioredoxin, a coenzyme of ribonucleotide reductase ; and deiodinases that remove I from thyroid hormones. Meat, dairy products, and grains are important dietary sources. Keshan disease, first identified in China, is a cardiomyopathy caused by eating foods produced from Se-deficient soil. Toxicity (selenosis) caused by overingestion of supplements causes brittle nails and hair. Cutaneous and neurologic effects may also be seen (UL = 400 μg in adults).