Zinc and copper levels in the breast-milk of Cape Town mothers.

Zinc and copper levels were measured longitudinally in the breast-milk of 55 healthy South African women from the middle and upper socio-economic classes. The mean foremilk zinc levels showed a significant fall (P less than 0,05) from 652,9 +/- 240,7 micrograms/dl at 3 days after delivery to 413,3 +/- 143,0 micrograms/dl at 7 days and 228,1 +/- 136,1 micrograms/dl at 6 weeks. Lower foremilk zinc levels were obtained at 36 weeks (64,3 +/- 50,0 micrograms/dl). In contrast, foremilk copper levels were low at 3 days (57,0 +/- 74,8 micrograms/dl), with a gradual decline to very low levels (28,0 +/- 29,7 micrograms/dl) at 36 weeks. No differences were detected between the fore- and hindmilk zinc and copper levels at any stage of lactation studied (P greater than 0,05).