Breast milk zinc transfer and early post-natal growth among urban South Indian term infants using measures of breast milk volume and breast milk zinc concentrations.

Zinc (Zn) deficiency in infancy and early childhood is of public health concern in developing countries. This study aimed to longitudinally assess Zn intake of urban South Indian term infants in the first 6 months of life using measures of breast milk (BM) volume and BM Zn concentrations and, additionally, to study the effect of BM Zn intake on infant length and weight gain. BM intake by the deuterium dilution technique, BM Zn concentration at months 1, 3 and 6, as well as serum Zn level at months 3 and 6 were assessed in 50 mother-infant pairs. BM intake significantly declined from 627 mL day(-1) at month 1 to 608 mL day(-1) at month 6 (P < 0.01). BM Zn concentration and intake significantly declined from month 1 to month 6 (P < 0.001 for both). Mean infant serum Zn level at months 3 and 6 were 93.0 ± 27.1 and 99.6 ± 30.1 µg dL(-1), respectively. Infant BM Zn intake at months 1 and 3 was not associated with the weight and length gain between 1-3 and 3-6 months, respectively. Zn intake from BM, maternal BM Zn content and serum Zn levels were not significantly different between small-for-gestational age and appropriate-for-gestational age infants. Therefore, among urban south Indian term infants less than 6 months of age, BM Zn intakes were low, owing to low volumes of BM intake, despite BM Zn concentrations being in the normal range. Promotion of breastfeeding and thereby increasing the volumes of milk produced is a first important step towards improving Zn intake among infants.