Effect of zinc supplementation on the dietary intake, rate of weight gain, and energy cost of tissue deposition in children recovering from severe malnutrition.

Children recovering from severe malnutrition on a milk based diet have low plasma zinc concentrations: children recovering on a soya based diet have much lower plasma zinc concentrations, lower rates of weight gain, and higher energy costs of tissue deposition. However, they do not demonstrate the clinical features of anorexia, diarrhea, and skin lesions usually associated with zinc deficiency. We therefore supplemented 16 children with zinc acetate on the basis that a therapeutic response to zinc constitutes the best evidence of a preexisting zinc deficiency. Fourteen of the 16 children had an immediate and definite increase in their rate of weight gain with zinc supplementation. This was associated with a decrease in the energy cost of tissue deposition, regrowth of the thymus, and activation of the sodium pump. We conclude that the children were indeed zinc deficient. We suggest that the anorexia of zinc deficiency is related to an inability to metabolize nitrogen in the zinc deficient state, and that our children did not show an appetitive response because of the relatively low protein content of the diets we used. Based on the premise that the abnormalities seen in our children may have been secondary to mild zinc deficiency, we suggest that limitation of lean tissue synthesis, with resultant obesity, and a propensity to infection are the major features of a mild zinc deficiency. Children undergoing a period of "catch up" weight gain or growth should have supplemental zinc, particularly if they have had diarrhea or if the use of a soya based formula is contemplated.