Zinc Concentrations in Human Milk During Lactation: a 6-month Longitudinal Study in Southern Brazil

Human milk zinc concentrations from women of low socioeconomic status in Ribeirao Preto, Southern Brazil, were studied. A group of 23 mothers, 17 multiparae and six primiparae aged from 17 to 39 years, were included in a 6-month longitudinal study. A total of 192 samples were collected starting from colostrum and then at 15-day intervals until the end of the sixth month of lactation. Initial zinc values (0.47 ± 0.10mg/dl) fell by about 40 per cent during the second week of lactation to 0.28 ± 0.06mg/dl, the decrease progressively increasing up to the 24th week (0.11 ± 0.03 mg/dl). Zinc values were significantly higher in the colostrum than in any of the later collections (P< 0.05). The values obtained at 15 days were significantly higher (P