Effect of iron supplementation on zinc and magnesium concentrations in maternal milk and plasma

Iron in the diet can influence the absorption of certain elements including zinc (Zn) and magnesium (Mg). In this study the effect of iron supplementation on zinc and magnesium concentrations in maternal milk and plasma at puerperal period were evaluated. Ninety nine non anemic mothers with single pregnancy and normal delivery were randomly enrolled in two groups (iron and placebo group); blood samples were collected at the time of delivery and also 140 mid 40 days after delivery. Milk samples were collected twice; at two weeks (transient milk) and 40 days after the delivery (mature milk). They were supplemented orally with either 150mg ferrous sulfate or placebo from the time of delivery for 40 days. Zinc and magnesium concentrations were measured using atomic absorption spectrometry. The maternal dietary intake for zinc and magnesium were similar between two groups. Mean iron indexes (ferritin, serum iron and TIBC) were not significantly different between two groups at the time of delivery. No significant differences in Zn and mg levels were detected in maternal milk between two groups but in plasma although there was no significant difference in plasma magnesium concentrations; The zinc concentrations was significantly (p<0.001) decreased in the group receiving iron supplementation (0.076±0.047mg/dL) compared with the group receiving placebo (0.163±0.137) until 40 days after delivery. Data from this study suggest that iron supplementation does not affect the contents of these elements in maternal milk but despite the possible improvement in body iron status, it can decrease the plasma zinc concentrations, so the zinc supplementation may be needed with iron