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Energy requirements, protein-energy metabolism and balance, and carbohydrates in preterm infants
William W Hay1, Laura D Brown, Scott C Denne
1Department of Pediatrics, Section of Neonatology, Perinatal Research Center, University of Colorado School of Medicine, Aurora, Colo., USA.
Insights
Preterm infants require specific energy and protein for growth. Excessive energy intake can lead to rapid fat gain and potential obesity, highlighting the need for careful nutritional management.
Area of Science:
- Neonatal nutrition
- Pediatric metabolism
- Infant growth and development
Background:
- Energy is crucial for all bodily functions, from molecular to systemic levels.
- Preterm infants have unique energy demands due to their physiology, metabolism, and growth requirements.
- Factors influencing energy expenditure include body size, postnatal age, diet, environment, and clinical status.
Purpose of the Study:
- To elucidate the critical role of energy and protein in preterm infant growth.
- To examine the relationship between energy intake, body composition changes (lean tissue vs. fat accretion), and long-term health risks.
- To explore the potential benefits of non-glucose carbohydrates in human milk for preterm infants.
Main Methods:
- Analysis of energy and protein requirements for basal metabolism and growth in preterm infants.
- Evaluation of factors affecting energy expenditure, including physiological and environmental influences.
- Assessment of the impact of different energy intake levels on lean tissue and fat accretion.
- Consideration of the role of specific nutrients like glucose, protein, fat, and non-glucose carbohydrates.
Main Results:
- Both energy and protein are essential for achieving normal growth rates in preterm infants.
- A higher protein-to-energy ratio is often needed to support intrauterine growth approximation.
- Energy intake above 80-90 kcal/kg/day in healthy preterm infants primarily drives fat accretion.
- Excessive energy intake is linked to rapid adiposity and increased risk of later-life obesity.
- Non-glucose carbohydrates in human milk may support growth and gut microbiome development.
Conclusions:
- Optimizing energy and protein intake is vital for appropriate growth and body composition in preterm infants.
- Careful management of energy delivery is necessary to prevent excessive fat gain and associated long-term health risks.
- Human milk oligosaccharides may offer additional benefits for preterm infant development and gut health.
Abstract:
Energy is necessary for all vital functions of the body at molecular, cellular, organ, and systemic levels. Preterm infants have minimum energy requirements for basal metabolism and growth, but also have requirements for unique physiology and metabolism that influence energy expenditure. These include body size, postnatal age, physical activity, dietary intake, environmental temperatures, energy losses in the stool and urine, and clinical conditions and diseases, as well as changes in body composition. Both energy and protein are necessary to produce normal rates of growth. Carbohydrates (primarily glucose) are principle sources of energy for the brain and heart until lipid oxidation develops over several days to weeks after birth. A higher protein/energy ratio is necessary in most preterm infants to approximate normal intrauterine growth rates. Lean tissue is predominantly produced during early gestation, which continues through to term. During later gestation, fat accretion in adipose tissue adds increasingly large caloric requirements to the lean tissue growth. Once protein intake is sufficient to promote net lean body accretion, additional energy primarily produces more body fat, which increases almost linearly at energy intakes >80-90 kcal/kg/day in normal, healthy preterm infants. Rapid gains in adiposity have the potential to produce later life obesity, an increasingly recognized risk of excessive energy intake. In addition to fundamental requirements for glucose, protein, and fat, a variety of non-glucose carbohydrates found in human milk may have important roles in promoting growth and development, as well as production of a gut microbiome that could protect against necrotizing enterocolitis.
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