Effect of carbohydrates on calcium absorption in premature infants

Premature infants are susceptible to diseases related to deficient dietary calcium intake. Studies in adults suggest carbohydrates can enhance calcium absorption. However, little is known about how carbohydrates affect calcium absorption in premature infants due to a lack of direct in vivo studies. We adapted the triple lumen perfusion method for use in premature infants to compare calcium absorption 36 mmol/L (1.44 gn) in the absence and presence of either 70 g/L lactose or glucose polymers. Ca-44 was added to determine endogenous calcium losses. Fourteen infants were studied (gestational age: 31 +/- 0.4 wk; study weight: 1590 +/- 105 g; mean +/- SEM). Calcium absorption from the glucose polymer solution was greater than that from the control and lactose solutions (0.17 +/- 0.05 mu mol . min(-1). cm(-1) versus 0.04 +/- 0.04 and 0.008 +/- 0.045 mu mol . min(-1). cm(-1), respectively). Calcium absorption correlated positively with water and carbohydrate absorption. The rate of carbohydrate absorption was greater from the glucose polymers than from the lactose solution (0.40 +/- 0.10 mg . min(-1). cm(-1) versus 0.22 +/- 0.06, respectively). Based upon Ca-44 absorption, endogenous calcium loss appeared to account for less than 1% of total calcium flux. We conclude that glucose polymers, but not lactose, enhance calcium absorption in the premature infant, a fact that may be useful in formula design.