Randomized trial of calcium glycerophosphate-supplemented infant formula to prevent lead absorption

Abstract

Background: Although additional dietary calcium is recommended frequently to reduce the risk of lead poisoning, its role in preventing lead absorption has not been evaluated clinically. Objective: The objective was to determine the safety and to estimate the size of the effect of calcium- and phosphorus-supplemented infant formula in preventing lead absorption. Design: One hundred three infants aged 3.5-6 mo were randomly assigned to receive iron-fortified infant formula (465 mg Ca and 317 mg P/L) or the same formula with added calcium glycerophosphate (1800 mg Ca and 1390 mg P/L) for 9 mo. Results: There was no significant difference between groups in the mean ratio of urinary calcium to creatinine, serum calcium and phosphorus, or change in iron status (serum ferritin, total iron binding capacity). At month 4, the median (±SD) increase from baseline in blood lead concentration for the supplemented group was 57% of the increase for the control group (0.04 ± 0.09 compared with 0.07 ± 0.10 μmol/L; P = 0.039). This effect was attenuated during the latter half of the trial, with an overall median increase in blood lead concentration from baseline to month 9 of 0.12 ± 0.13 μmol/L for the control group and 0.10 ± 0.18 μmol/L for the supplemented group (P = 0.284). Conclusions: Supplementation did not have a measurable effect on urinary calcium excretion, calcium homeostasis, or iron status. The significant effect on blood lead concentrations during the first 4 mo was in the direction expected; however, because this was not sustained throughout the 9-mo period we cannot conclude that the calcium glycerophosphate supplement prevented lead absorption in this population.