Dietary carbohydrate assimilation in the premature infant: evidence for a nutritionally significant bacterial ecosystem in the colon

Abstract
Carbohydrate energy absorption and breath hydrogen concentration were measured in 12 premature infants 28–32 wk gestational age and 2–4 wk postnatal age. Each of two groups of six infants were randomly assigned to receive one of two formulas that differed only in carbohydrate source: 100% lactose (LAC) or 50% lactose: 50% glucose polymer (LAC + GP). In 11 infants the peak breath hydrogen concentration suggested extensive colonic fermentation (range 44–239 ppm/5% CO2 or 44–239 microL/L per 50 mL/L CO2). An approximate 100% increase in lactose intake in the LAC group was associated with a similar increase in breath hydrogen concentration at 30, 60, and 120 min. None of the infants exhibited diarrhea or vomiting or developed delayed gastric emptying. Carbohydrate energy absorption (mean +/- SD) was, respectively, 86 +/- 5% and 91 +/- 3% in the LAC and the LAC + GP groups (p greater than 0.05). Thus, colonic bacterial fermentation may be critical to energy balance and to the prevention of osmotic diarrhea in premature infants fed lactose.