Relationships among plasma zinc, plasma prolactin, milk transfer, and milk zinc in lactating women

Abstract

The objective was to analyze interrelationships among plasma zinc (PZ), plasma prolactin (PRL), milk transfer, and milk zinc from a longitudinal study of lactating women with a range of zinc intakes. Sixteen of 26 women received a 15 mg/d zinc supplement, resulting in a significant increase in total zinc intake compared with nonsupplemented participants (P<.001). No significant differences in key variables were observed between the zinc-supplemented and non-zinc-supplemented women; data were thus combined. An inverse trend between PRL and PZ was observed at 0.5 (r=-.36, P=.08) and 7 months (r=-.38, P=.06). Correlations between PRL at 0.5 months and at 3, 5, and 7 months were significant (r>.50, P<.01). PRL concentrations and milk transfer were positively correlated at 5 (r=.67, P<.001) and 7 months (r=.53, P<.01), consistent with PRL role in lactation maintenance. Studies including zinc-deficient lactating women are required to clarify the interrelationships between zinc status and PRL secretion.