Zinc is an essential nutritional requirement and serves as a cofactor for more than 70 different enzymes including carbonic anhydrase, alkaline phosphatase, lactic dehydrogenase, and both RNA and DNA polymerase. Zinc facilitates wound healing, helps maintain normal growth rates, normal skin hydration, and the senses of taste and smell.
Zinc resides in muscle, bone, skin, kidney, liver, pancreas, retina, prostate and particularly in the red and white blood cells. Zinc binds to plasma albumin, α2-macroglobulin, and some plasma amino acids including histidine, cysteine, threonine, glycine, and asparagine. Ingested zinc is excreted mainly in the stool (approximately 90%), and to a lesser extent in the urine and in perspiration.
Providing zinc helps prevent development of deficiency symptoms such as: Parakeratosis, hypogeusia, anorexia, dysosmia, geophagia, hypogonadism, growth retardation and hepatosplenomegaly.
The initial manifestations of hypozincemia in total parenteral nutrition are diarrhea, apathy and depression. At plasma levels below 20 mcg zinc/100 mL dermatitis followed by alopecia has been reported for total parenteral nutrition patients. Normal zinc plasma levels are 100 ± 12 mcg/100 mL.