The human milk contents of iron, copper, zinc, calcium and magnesium in a population with a habitually high intake of iron.

Abstract

The contents of iron, copper, zinc, calcium and magnesium were determined in human milk samples from 18 Ethiopian and 23 Swedish women. The Ethiopian women belonged to two groups with different socio-economic situations, a non-privileged and a privileged group. Both groups had an excessively high dietary iron intake--20 to 30 times that of the Swedish women--from the iron-rich traditional diet. In spite of this, the mean concentrations of iron in the milk, as well as of zinc and magnesium, were similar in all three groups. The mean copper concentration, however, was significantly lower in the Ethiopian than in the Swedish milk samples, the lowest mean value occurring in the privileged group. In contrast, a significantly higher mean calcium concentration was found in milk samples from the Ethiopian women than from the Swedish, the highest mean concentration being noted in the non-privileged group. The levels of minerals in breast milk showed no correlation to the birth weight of the infants or the length of gestation. Our data suggest that an excessively high dietary iron intake does not increase the breast milk content of iron in mothers with a good iron status. The reasons for the differences in the content of copper between the Ethiopian and Swedish milk samples are unclear. The higher calcium content in milk from the Ethiopian mothers, despite a low dietary calcium intake may be a result of an increased endogenous cholecalciferol synthesis due to greater exposure to sunshine.