Zinc is lost from the body primarily through the feces (Figure 1). Feces contain unabsorbed dietary zinc, zinc contained within intestinal epithelial cells that have been sloughed off, and endogenous zinc secretions into the gut from the pancreas, the gall bladder, and the cells lining the gastrointestinal tract. The endogenous secretions and the extent to which they are reabsorbed can be controlled and constitute an important homeostatic mechanism for regulating zinc status. Zinc losses in urine are relatively minor but do respond to extremes of intake to help maintain homeostasis. Shed skin cells, sweat, hair, menstrual blood, and semen are additional routes of loss.

appears to be necessary for normal zinc absorption. The zinc efflux protein ZnT-1 is found at the baso-lateral membrane and probably promotes the passage of zinc out of the intestine. Acrodermatitis entero-pathica can be treated with large doses of zinc, supporting the existence of paracellular transport at high intake levels. A large amount of zinc is secreted into the gut from the pancreas and intestine (Figure 1). Malabsorption syndromes can lead to a failure to reabsorb these endogenous secretions and, hence, to rapid loss of body zinc.

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Gaining Weight 101

Gaining Weight 101

Find out why long exhausting workouts may do more harm than good. Most of the body-building workout and diet regimens out there are designed for the guys that gain muscle and fat easily. They focus on eating less and working out more in order to cut the excess fat from their bodies while adding needed muscle tone.

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