The effect of calcium supplementation on blood lead levels in Nigerian children

Abstract

Objective: To determine whether calcium supplementation alters the risk of lead toxicity.

Study design: Children aged 12-18 months from 3 communities in Nigeria were assigned to receive daily calcium supplementation, as either calcium carbonate (400 mg) or ground dried fish (529 ± 109 mg), or placebo. All children received 2500 IU of vitamin A. Levels of blood lead, calcium, and vitamin D metabolites were measured at baseline and after 12-18 months (n = 358).

Results: The mean (± SD) baseline lead level was 11.1 ± 7.8 μg/dL (range, 1-43 μg/dL; median, 9 μg/dL); 44.7% of subjects had a lead level >10 μg/dL. After 12-18 months, the mean lead level was 8.1 ± 6.3 μg/dL (range, 1-48 μg/dL; median, 6 μg/dL), with 22.6% with a level >10 μg/dL. Lead levels at baseline varied among communities (P = .01) and were higher in children who used eye cosmetics or lived near a lead-acid battery melter (both P < .001). In a multiple regression model, the decrease in blood lead level was predicted by age, baseline lead level, and time of final lead value at 12-18 months (R(2) = 31%), but not by calcium supplementation (P = .98).

Conclusions: Lead toxicity is common in Nigerian children, but calcium supplementation does not affect blood lead levels.