Impact of zinc supplementation on breast milk zinc levels among low socioeconomic indian women

Zinc supplementation does not affect breast milk zinc in women with adequate zinc status. To evaluate if this is also true of settings where zinc deficiency is more prévalent, a randomized, double blind trial of zinc supplementation was conducted in a low-socioeconomic urban Indian setting where usual diet is low in zinc, and high in inhibitors of zinc absorption.Lactating women 0-2 mo and 4-6 mo postpartum were identified, and using a stratified randomization were allocated to receive zinc 20 mg daily in 2 doses (n = 50 0-2 mo, n = 51 4-6 mo) or control preparation (n=61 0-2 mo and n = 50 4-6 mo). A midfeeding 10 ml breast milk sample was collected before and after supplementation for 30 days. Median breast milk zinc concentrations (urnol/L) in first 6 months of lactation were 62.8, 32.2, 23.1. 16.3, 18.3, 18.5, respectively. Both in 0-2 months and 4-6 months strata the change in zinc levels was not significantly different beween zinc (Z) and control (C) groups (0-2 mo Z-18.9 4. 28.2, C-22.1±16.1; 4-6 mo Z-2.6±6.6, C 0-6 ± 9.5). Among women 0-2 mo postpartum with baseline level < 45.0 umol/l, the zinc supplementation group had caused a significantly less decrease in breast milk zinc (Z 1.4 ±. 19.5, C 9.7 ± 8.5, p = 0.05). The same was not true for women 4-6 mo postpartum. We conclude that in deficient populations, breast milk zinc concentrations are similar to adequately nourished populations, with a high individual variability. Zinc supplementation affected breast milk levels in early lactation, in a subgroup with low breast milk zinc concentrations.