Little is known about the zinc content of breast milk in developing countries. Zinc content in breast milk was analyzed in 34 mothers of low socio-economic status; 17 were primiparae and 17 multiparae. Women in their 6th to 36th week of lactation provided 3 samples of breast milk at different times within a single day. The mean zinc concentration in breast milk (micrograms/ml) was 1.89 +/- 0.64 with a range from 0.17 to 4.38 micrograms/ ml. Zinc content in the morning, midday and evening samples were 2.1 +/- 0.84, 1.74 +/- 0.53, 1.84 +/- 0.69 respectively. There was significant variation between morning and midday samples (p = 0.038). Maternal age, parity, nutritional status or age of the child did not affect the zinc content of milk in the population studied.
PIP: Deficient dietary zinc intake has been associated with diminished growth velocity. Until the age of 4-6 months, milk is the only dietary source of zinc for most infants. This study investigated the zinc content of mature breast milk of low-income Bangladeshi mothers. Enrolled were 34 exclusively breast-feeding mothers of low socioeconomic status in the 6th-36th week of lactation, who submitted 3 samples of breast milk at different times (5-7 a.m., 2-3 p.m., and 10 p.m.) within a single day. Two-thirds of these mothers had a body mass index less than 20. Only 20.5% of the 102 total milk samples contained at least 3 mcg/ml of zinc, the recommended daily intake. The range was 0.17-4.38 mcg/ml. The average zinc content was 2.10 mcg/ml in the early morning, 1.74 mcg/ml at mid-afternoon, and 1.84 mcg/ml at late evening. There were significant differences between the morning and mid-afternoon samples. Breast milk's zinc content was not associated with maternal age, parity, maternal body mass index, or age of the child. The low zinc content of breast milk identified in this study raises serious concerns about the growth and development of the children of low-income women in Bangladesh and other developing countries.