Related Experiment Videos
Development of carbohydrate absorption in the fetus and neonate
Insights
Human fetal development shows sequential maturation of carbohydrate absorption mechanisms. While some enzymes mature in utero, others like pancreatic amylase develop postnatally, with breath hydrogen testing aiding assessment in infants.
Area of Science:
- Human fetal development
- Gastroenterology
- Nutritional science
Background:
- Carbohydrate absorption mechanisms mature sequentially during human fetal development.
- Intestinal enzymes like lactase, sucrase, and maltase are mature in term fetuses.
- Pancreatic amylase activity and glucose transport mature postnatally, remaining low in neonates.
Purpose of the Study:
- To outline the developmental patterns of carbohydrate absorption in human fetuses and neonates.
- To describe the enzymatic and transport mechanisms involved in carbohydrate digestion and absorption.
- To discuss the clinical implications and diagnostic methods for assessing carbohydrate absorption in infants.
Main Methods:
- Review of developmental physiology of carbohydrate absorption.
- Analysis of enzyme activity and glucose transport maturation.
- Discussion of postnatal adaptive responses and colonic fermentation.
- Evaluation of breath hydrogen testing as a diagnostic tool.
Main Results:
- Intestinal enzymes (lactase, sucrase, maltase, isomaltase, glucoamylase) mature in the term fetus.
- Pancreatic amylase and glucose transport mature postnatally, with low levels in neonates.
- Lactase activity increases with gestational age but may be low in preterm infants; clinical lactose intolerance is rare.
- Colonic fermentation salvages unabsorbed carbohydrates, producing hydrogen gas and short-chain fatty acids.
Conclusions:
- Carbohydrate absorption mechanisms exhibit distinct developmental timelines in fetal and neonatal periods.
- Postnatal adaptation and colonic fermentation contribute to overall carbohydrate assimilation.
- Breath hydrogen testing offers a noninvasive method for evaluating carbohydrate absorption status in infants.
Abstract:
Maturation of mechanisms for carbohydrate absorption occurs in a defined sequence during human fetal development. The intestinal enzymes, lactase, sucrase, maltase, isomaltase, and glucoamylase, are at mature levels in the term fetus. Mature levels of pancreatic amylase activity and glucose transport occur postnatally, and levels are low in both the term and preterm neonate. In the preterm infant, sucrase, maltase, and isomaltase are usually fully active, but lactase activity, which increases markedly from 24 to 40 weeks, may be low depending upon fetal age. Despite these developmental patterns, clinical lactose intolerance is uncommon. Postnatal adaptive responses to ingested carbohydrates lead to competent carbohydrate absorption. Inadequately absorbed carbohydrates are salvaged by colonic flora through fermentation of carbohydrates to hydrogen gas and short-chain fatty acids; the latter are readily absorbed by the colon. In this setting, carbohydrate tends to be absent from the stool. Noninvasive reflection of the status of carbohydrate absorption may be obtained from breath hydrogen testing, a technique of particular value in young infants.