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Energy balance and metabolic rate in preterm infants fed with standard and high-energy formulas
Insights
High-energy infant formulas increased metabolic rate (MR) but did not improve growth in preterm infants. Increased energy intake was at the expense of growth, suggesting no short-term advantage for these formulas.
Area of Science:
- Neonatal nutrition
- Pediatric gastroenterology
- Infant metabolism
Background:
- Low birth weight preterm infants often require specialized nutritional support.
- Standard infant formulas may not meet the high energy demands of these vulnerable infants.
Purpose of the Study:
- To evaluate the effects of high-energy infant formulas on energy balance, absorption, metabolic rate, and growth in preterm infants.
- To compare formulas with different energy densities and fat sources (peanut oil vs. medium-chain triglycerides).
Main Methods:
- Energy balance studies were conducted over 7-10 days on sixteen preterm infants.
- Infants received a standard formula and four high-energy formulas with varying energy densities.
- Anthropometric measurements and metabolic rate (MR) were determined.
Main Results:
- Energy retention decreased with higher energy formulas, falling below 50% on the most energy-dense feeds.
- Net absorption of dietary energy increased with all high-energy formulas, irrespective of fat source.
- Advancing infant maturity improved net energy absorption.
- Fasting and postprandial metabolic rates increased significantly with the highest energy feeds.
Conclusions:
- High-energy infant formulas, particularly those with higher densities, increased metabolic rate at the expense of growth in preterm infants.
- Short-term use of these high-energy formulas likely offers no advantage for infant growth.
- Further research is needed to optimize nutritional strategies for preterm infants.
Abstract:
1. Energy balances were performed on sixteen low birth weight preterm infants over 7-10 d periods on a standard low-solute infant formula (2600 kJ/l), and on four high-energy formulas, providing different energy densities up to 3760 kJ/l. In two of the high-energy formulas the additional fat energy was provided by peanut oil, and the other two by medium chain triglycerides (MCT). Anthropometric measurements and metabolic rate (MR) determinations were made during the balance periods. 2. Mean energy retention on the standard formula was 66% of the intake and declined to below 50% on the two feeds providing the highest energy. Extensive energy balance data on the standard formula are available for reference. 3. Net absorption of dietary energy increased on all the high-energy formulas, rising from 362 kJ/kg per d on the standard formula to 453 kJ/kg per d on the highest energy-formula (P < 0.001). There was no advantage in using MCT. 4. Net absorption of dietary energy improved with advancing maturity, irrespective of the formula. 5. In spite of the increased dietary energy retention, there was no increase in growth rate during periods of feeding with the high-energy formulas. 6. Fasting and postprandial MR increased by 10.4 and 12.8% respectively on the highest energy feeds. 7. It is concluded that, at least in the short term, this type of high-energy feeding increases MR at the expense of growth and thus is probably of no advantage to the infant.