Infant formula iron dialysability related to other nutrients

The dialysable iron in relation to total iron, to protein sources, to calcium, magnesium, copper, zinc, and vitamin C of 17 infant formulas, from four different multinational companies were analyzed. Total iron, calcium, magnesium, copper, and zinc were determined by atomic absorption spectrophotometry. The dialysable iron was determined. The considered vitamin C concentration was that declared on the labels. There was no significant statistical relationship between total iron and dialysable iron (P = 0.54, r = 0.09) when considered separately. When analyzed considering protein sources, this relationship was shown to be inversely proportional to protein hydrolysate (P = 0.03, r = −0.72), and soy protein (P = 0.02, r = −0.93). The percentage of dialysable iron was significantly greater from the protein hydrolysate (P < 0.01). The dialysable iron showed a negative correlation with calcium (P < 0.05, r = −0.61). In conclusion, the infant formulas whose protein sources are casein and casein plus whey protein should present Ca:Fe and Fe:vitamin C ratios that allow considerable iron dialysability.