Effect of heat treatment of human milk on absorption of nitrogen, fat, sodium, calcium, and phosphorus by preterm infants.

Seven very low birthweight (less than 1.3 kg) preterm infants, aged between 3 and 6 weeks were fed raw, pasteurised, and boiled human milk for 3 consecutive weeks. Serial metabolic balance techniques were used to assess the absorption and retention of calcium, phosphorous, sodium, and nitrogen, and the absorption of fat. Fat absorption was reduced by approximately one-third when raw milk was heated. It is suggested that the improved fat absorption from the raw milk may be related to the preservation of milk lipases. A reduction in the amount of N retained was also noted when the infants were fed boiled milk. There were no obvious differences in the absorption of N or the absorption and retention of Ca, P, and Na between the three milks. All infants gained weight most rapidly during the week in which they were fed raw milk. The mean weight gain during this time was approximately one-third greater than that during similar periods when pasteurised or boiled milk was administered