Copper, zinc, and magnesium content of breast milk of Indian women.

Copper, zinc, and magnesium contents were determined in samples of breast milk obtained from 412 women in a low income group, from 100 women in a high income group of an urban population, and from 22 women from a low income group living in a rural area. Paired samples of milk and serum were collected from 152 women and the concentrations of copper and zinc in these two fluids were estimated. Copper levels fell from 0.46 microgram/ml in colostrum to 0.17 microgram/ml at 7 to 12 months of lactation; zince levels fell from 5.32 to 1.12 microgram/ml by 7 months. Magnesium level in colostrum was 40 micrograms/ml and reached a stable level of around 30 micrograms/ml in mature milk samples. Concentrations of copper and zinc in serum were not correlated with those in milk. Day to day and diurnal variations in the concentrations of these elements in milk were not significant indicating thereby that analysis of one sample provides satisfactory information of the trace element content in milk. There were no differences in the levels of these elements in milk between rural and urban low income groups of women. However significant differences were noted in the copper and zinc contents of milk of women from low and high income groups of the urban population, from the 1st to 3rd month of lactation.