Red blood cell glutathione peroxidase activity as a function of selenium supplementation in dietary treated children with phenylketonuria.

Red blood cell glutathione peroxidase (GSH-Px) activity of six patients with phenylketonuria treated with aminoacid mixture and protein hydrolysate diets was significantly lower (11.2 IU/g Hb) than that of 21 age-matched healthy children (14.9 IU/g Hb). When the diets were supplemented with yeast rich in selenium the red blood cell GSH-Px activity increased already after one month of treatment to 16.1 IU/g Hb (P less than 0.001) and remained at that level during subsequent two months of selenium supplementation. A high significantly positive correlation has been found between calculated red blood cell selenium level and GSH-Px activity within three months of selenium supplementation.