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In vivo estimation of lactose hydrolysis in premature infants using a dual stable tracer technique
C L Kien1, K Ault, R E McClead
1Department of Pediatrics, Ohio State University, Columbus.
Insights
Premature infants efficiently digest lactose by 34 weeks postconceptional age. This study used stable isotope tracers to confirm lactose digestion capacity in preterm infants, indicating effective lactose hydrolysis.
Area of Science:
- Neonatal Physiology
- Gastroenterology
- Nutritional Science
Background:
- Premature infants often exhibit immature digestive systems.
- Lactose digestion is crucial for nutrient absorption in neonates.
Purpose of the Study:
- To assess the lactose digestion capacity in premature infants.
- To determine the efficiency of in vivo lactose hydrolysis in preterm neonates.
Main Methods:
- Administered [1-13C]glucose and D-[1-13C]lactose via orogastric infusions.
- Monitored plasma glucose isotopic enrichment using specific isotopomers.
- Calculated isotopic enrichment of plasma glucose (C-1) corrected for recycling.
Main Results:
- The fraction of dietary lactose hydrolyzed in vivo averaged 1.02 +/- 0.16.
- This indicates efficient lactose digestion in the study population.
Conclusions:
- Lactose digestion is efficient by 34-weeks postconceptional age in premature infants.
- The findings support the adequate digestive capacity for lactose in late preterm infants.
Abstract:
To investigate their putative capacity for lactose digestion, primed continuous orogastric infusions of [1-13C]glucose and D-[1-13C]lactose were administered on consecutive days to five premature infants (30-31 wk gestation, 15-32 days of age), who were fed by orogastric infusions of human milk or formula. By monitoring the plateau isotopic enrichment of plasma glucose using isotopomers containing the entire derivatized glucose molecule or C-2 through C-6, we were able to distinguish label appearing in the peripheral circulation deriving from unmetabolized glucose from that arising from recycled or fermented glucose (or lactose). Isotopic enrichment of the C-1 of glucose, corrected for recycling, was then calculated during each tracer infusion, and the fraction of dietary lactose subjected to in vivo hydrolysis was estimated from these values and the respective tracer infusion rates, assuming similar absorptive and metabolic fates of labeled glucose arising from either tracer. This fraction averaged 1.02 +/- 0.16 (SD), suggesting that lactose digestion is efficient by 34-wk postconceptional age.