Evidence for defective skeletal mineralization in low-birthweight infants: the absorption of calcium and fat
Shaw, J.C.
Pediatrics 57(1): 16-25
1976
ISSN/ISBN: 0031-4005 PMID: 946131 Document Number: 104647
The absorption and retention of Ca and the absorption of fat were measured by serial metabolic balance techniques over the first 30 to 70 days of life in 11 preterm and 2 full-term low-birthweight infants fed on full-cream cow's milk, half-skimmed cow's milk, the proprietary filled milk S.M.A. (John Wyeth and Brothers, Ltd., Taplow, Maidenhead, Berks., UK) or breast milk. The values for Ca intake, absorption, and retention were compared with the rate of accumulation of Ca by the foetus in utero, which was calculated from published data on the chemical composition of foetal bodies. Infants on breast milk had an absolute dietary deficiency of Ca. Those on other milks ingested sufficient but they did not absorb enough. Though Ca absorption increased with increasing postnatal age, intrauterine rates of Ca retention were never achieved on any of the milks. The average retention of Ca by preterm infants as a percentage of intrauterine accumulation was for cow's milk 38%, for S.M.A. 27% and for breast milk 17%. The full-term light-for-dates infants absorbed and retained more Ca than the preterm infants; it was on average 52% of the amount accumulated by the human foetus for an equivalent weight gain. The average absorption of fat by preterm infants was from the cow's milk preparations 55%, from S.N.A. 61% and from breast milk 84%. The low-birthweight infants absorbed on average 87% of the breast milk fat. There was no evidence that the amount of Ca absorbed was influenced by fat malabsorption. The principal determinants of the amount of Ca absorbed were the length of gestation and postnatal age of the infant.