Growth of infants fed a zinc supplemented formula.

Some infant milk formulae have a lower zinc content than the original cow's milk. Zinc is a nutrient necessary for growth and, in this double-blind controlled study, the effects of supplementing Similac with iron with 4 mg/liter of zinc were determined. By 6 months of age, mean growth increments for the supplemented male infants were 2.1 cm greater in length (P less than 0.025) and 535 g greater in weight (P less than 0.05) than for male controls. Growth increments for female test and control infants did not differ significantly. Plasma zinc levels were, at 3 months of age, significantly higher for both male and female supplemented infants. By 6 months, only the male supplemented infants maintained significantly higherplasma zinc levels (P less than 0.025). The addition of zinc was associated with a lower incidence of disturbed gastrointestinal function (P less than 0.005) and not accompanied by any signs of toxicity.