Calcium, magnesium and phosphorus concentrations in human milk and in sera of nursing mothers and their infants during 26 weeks of lactation.

Longitudinal calcium, magnesium and phosphorus concentrations were measured in milk and sera of 20 nursing mothers and their infants during a period of 26 weeks. Within this period, progressive increase in serum calcium, magnesium and total protein concentrations were observed in breast-fed infants, in association with decreasing phosphorus content of breastmilk. Maternal serum calcium, magnesium and total protein concentrations also increased during this period. It is speculated that a decrease in serum phosphorus in breast-fed infants can cause rickets. It is also speculated that the physiological rise in serum calcium concentrations in maternal serum may be related to the physiological increase in serum total protein.