THE ESSENTIAL ROLE OF ZINC IN GROWTH

Zinc is known to play a relevant role in growth and development. The b asic mechanisms of action of this trace element are intimately linked to the structure and action of countless enzymes involved in many diff erent metabolic processes. In this respect, when zinc specifically act s on cartilage growth it is involved in multiple enzymatic reactions w hich make this a multifactorial event. Thus, we may divide the actions of zinc into three distinct types: 1) action on taste and smell acuit y, appetite regulation, and food consumption and regulation; 2) action on DNA and RNA synthesis stimulating a) cell replication and differen tiation of chondrocytes, osteoblasts and fibroblasts; b) cell transcri ption culminating in the synthesis of somatomedin-C (liver), alkaline phosphatase, collagen and osteocalcin (bone), and c) protein, carbohyd rate and lipid metabolism, that is intimately related to the mechanism s of smell, taste, appetite, and food consumption and utilization; 3) action on hormonal mediation by participating in a) GH synthesis and s ecretion in somatomammotroph cells, b) the action of GH on liver somat omedin-C production, and c) somatomedin-C activation in bone cartilage . In addition to these multiple functions, zinc also interacts with ot her hormones somehow related to bone growth such as testosterone, thyr oid hormones, insulin, and vitamin D-3. On the basis of the above cons iderations, we conclude that the integration of these mechanisms contr ibutes to the perfect physiological functioning of bone. Tn the presen ce of zinc deficiency, this homeostasis is impaired, causing the weigh t-height deficiency detected in several species studied, the human spe cies in particular.