TAILIEUCHUNG - Chapter 071. Vitamin and Trace Mineral Deficiency and Excess (Part 12)

Zinc Zinc is an integral component of many metalloenzymes in the body; it is involved in the synthesis and stabilization of proteins, DNA, and RNA and plays a structural role in ribosomes and membranes. Zinc is necessary for the binding of steroid hormone receptors and several other transcription factors to DNA. Zinc is absolutely required for normal spermatogenesis, fetal growth, and embryonic development. Absorption The absorption of zinc from the diet is inhibited by dietary phytate, fiber, oxalate, iron, and copper, as well as by certain drugs including penicillamine, sodium valproate, and ethambutol. Meat, shellfish, nuts, and legumes are good sources of bioavailable. | Chapter 071. Vitamin and Trace Mineral Deficiency and Excess Part 12 Zinc Zinc is an integral component of many metalloenzymes in the body it is involved in the synthesis and stabilization of proteins DNA and RNA and plays a structural role in ribosomes and membranes. Zinc is necessary for the binding of steroid hormone receptors and several other transcription factors to DNA. Zinc is absolutely required for normal spermatogenesis fetal growth and embryonic development. Absorption The absorption of zinc from the diet is inhibited by dietary phytate fiber oxalate iron and copper as well as by certain drugs including penicillamine sodium valproate and ethambutol. Meat shellfish nuts and legumes are good sources of bioavailable zinc whereas zinc in grains and legumes is less available for absorption. Deficiency Mild zinc deficiency has been described in many diseases including diabetes mellitus HIV AIDS cirrhosis alcoholism inflammatory bowel disease malabsorption syndromes and sickle cell disease. In these diseases mild chronic zinc deficiency can cause stunted growth in children decreased taste sensation hypogeusia and impaired immune function. Severe chronic zinc deficiency has been described as a cause of hypogonadism and dwarfism in several Middle Eastern countries. In these children hypopigmented hair is also part of the syndrome. Acrodermatitis enteropathica is a rare autosomal recessive disorder characterized by abnormalities in zinc absorption. Clinical manifestations include diarrhea alopecia muscle wasting depression irritability and a rash involving the extremities face and perineum. The rash is characterized by vesicular and pustular crusting with scaling and erythema. Occasional patients with Wilson s disease have developed zinc deficiency as a consequence of penicillamine therapy Chap. 354 . The diagnosis of zinc deficiency is usually made by a serum zinc level of 12 iimol l 70 iig dL . Pregnancy and birth control pills may cause a slight depression in

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