The effects of zinc supplementation on zinc, retinol and carotene levels in lactating Amazonian women

Abstract

The effects of zinc supplementation on levels of zinc, retinol and carotene in serum and breast milk were investigated in a double blind controlled prospective study amongst 66 poor urban Amazonian mothers in 1981. The mothers predominantly breast-fed their infants for the first five months of life and took supplements from soon after birth. Milk retinol levels were already significantly higher in zinc supplemented (ZS) than non-zinc supplemented (NZS) mothers by one month post-partum, and by four months had risen significantly in the ZS mothers but fallen in NZS mothers. At four months post-partum, milk retinol levels of ZS mothers were near normal and double those of NZS mothers. The effect of zinc supplementation on these retinol levels was possibly associated with an increased absorption and utilization of dietary carotene, since milk carotene levels also increased in ZS mothers to levels three times those of NZS mothers at four months post-partum. This impact of zinc supplementation on maternal and breast milk vitamin A levels has not been shown previously and is of potential relevance where zinc and vitamin A deficiency are common.