Effect of infant cereals on zinc and copper absorption during weaning.

Zinc and copper absorption from five infant cereal products mixed with water, human milk, or cow's milk was measured using an in vivo absorption model (rat pup) involving gastric intubation of extrinsically radiolabeled diets. Whole-body copper 64 uptake, nine hours after intubation, ranged from 14% to 31% of the dose given for the different cereal combinations. The resultant bioavailability of copper from human milk-cereal combinations (23% to 26%) was significantly lower than that from human milk alone (38%). Whole-body zinc 65 uptake, nine hours after intubation, ranged from 13% to 54% of the dose given for the different cereal combinations. These values were significantly lower than the whole-body zinc 65 uptake from milk alone (61%). Zinc availability was lower (13% to 25%) from dry cereal combinations that contained phytic acid (oatmeal and high-protein varieties) compared with the ready-to-serve cereal-fruit combinations (24% to 54%). The highest zinc uptake (37% to 54%) was from rice-fruit combinations that do not contain phytic acid. We estimated the amounts of zinc and copper that would be absorbed from these cereal products and speculated on the potential impact of these foods on the weaning infant's zinc and copper nutriture. Depending on the feeding practices employed during the weaning period, it is apparent that infant cereals may compromise utilization of zinc and copper from milk diets during weaning.