Zinc and copper in human nutrition.

Abstract

of the off-spring of pre<gnant rats fed severely zinc-depleted diets are malformed at term (Hurley, Gowan & Swinerton, 1971). Zinc is also important for normal taste and smell, but the long suggested role of this element in wound healing is less clearly established; at least in man. The presence of copper in almost all forms of living tissue was recognised early in the nineteenth century, but its key role in vertebrate metabolism was not established until 1928 when copper was found to be essential, together with iron, for normal erythropoiesis. Not all the cupro-enzymes so far identified have defined physiological roles, but a number of associations have been recognised in animals and some in man. Defects which affect the cardiovascular system of copper-deficient animals are believed to be related to disorders of cross-linking of the connective tissue proteins caused by deficiency of the cupro-enzyme, lysl oxidase. Disorders of the central nervous system have also been linked to copper deficiency in a number of animal species and lack of the cupro-enzyme tryrosinase is thought to account for the failure of melanin formation, achromotrichia, in animals with pigmented hair, wool, or feathers. Copper is so widely distributed that in humans acquired deficiency has long been regarded as unlikely and it was not until 1972 that studies during total parenteral nutrition (Karpal 8c Peden, 1972) linked copper deficiency in an infant with a syndrome characterised by anaemia, neutropenia and scorbutic type bone lesions. Administration of copper rapidly corrected the haematological abnormalities but the bone defects were slower to respond, although they eventually returned to normal. ZINC Biochemistry In 1940 Keilin & Mann established that zinc was an essential component of the enzyme carbonic anhydrase; but it was not until 1954 that a second enzyme, bovine pancreatic carboxy peptidase A, was also found to contain zinc in an essential biological role. Over the past decade, however, progress has been very