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Metabolic consequences of increasing energy intake by adding lipid to parenteral nutrition in full-term infants
J E Van Aerde1, P J Sauer, P B Pencharz
1Department of Pediatrics, University of Toronto, Canada.
Insights
Adding intravenous lipids to parenteral nutrition in neonates improves nitrogen retention and utilization without altering metabolic rate. This suggests optimized energy intake is key for nutrient utilization in intravenously fed infants.
Area of Science:
- Neonatal nutrition
- Pediatric metabolism
- Intravenous feeding
Background:
- Parenteral nutrition is crucial for neonates unable to receive enteral feeding.
- Optimizing energy and nutrient delivery is essential for growth and development in this population.
- Understanding fuel utilization and metabolic response to different nutrient compositions is vital.
Purpose of the Study:
- To investigate the impact of increased energy intake, specifically from intravenous lipids, on energy metabolism and fuel utilization in neonates.
- To determine if adding lipids to a glucose and amino acid regimen affects nitrogen retention and substrate oxidation.
- To assess the relationship between energy intake, diet composition, and energy expenditure in intravenously fed infants.
Main Methods:
- A study involving twenty intravenously fed neonates divided into two groups.
- Group 1 received a total energy intake of 261 kJ.kg-1 x d-1, while Group 2 received 355 kJ.kg-1 x d-1.
- Group 2 received additional intravenous lipids (2 g.kg-1 x d-1) alongside glucose and amino acids, with metabolic rate and gas exchange monitored.
Main Results:
- No significant differences were observed in metabolic rate, respiratory gas exchange, or nonprotein substrate oxidation between the groups.
- The addition of lipids significantly enhanced nitrogen retention (306 vs 230 mg.kg-1 x d-1) and nitrogen utilization (66.5% vs 52.8%).
- Increased energy intake via lipids improved nitrogen utilization without increasing overall energy expenditure or altering key metabolic parameters.
Conclusions:
- Intravenous lipid supplementation in parenteral nutrition improves nitrogen utilization in neonates.
- Increased energy intake through lipids can enhance nutrient utilization without adversely affecting metabolic rate or substrate oxidation.
- Energy expenditure in parenterally fed neonates does not necessarily increase proportionally with energy intake, depending on diet composition.
Abstract:
The effect on energy metabolism and fuel utilization of increasing energy intake by adding intravenous lipid to a glucose and amino acid regimen was examined. Twenty fullterm, appropriate-for-gestational-age, intravenously fed neonates were entered into one of two groups: total energy intake was 261 kJ.kg-1 x d-1 (62 kcal.kg-1 x d-1) in group 1 and 355 kJ.kg-1 x d-1 (85 kcal.kg-1 x d-1) in group 2. Both groups received 2.8 g protein.kg-1 x d-1 and 14 g glucose.kg-1 x d-1. Group 2 received an additional 2 g lipid.kg-1 x d-1. Metabolic rate, respiratory gas exchange, and nonprotein substrate oxidation were similar in both groups. The addition of energy as lipid enhanced nitrogen retention (230 vs 306 mg.kg-1 x d-1; P < 0.02) and utilization (52.8% vs 66.5%; P < 0.03). Our data suggest that nitrogen utilization is improved in parenterally fed neonates by adding fat and increasing energy intake without change in metabolic rate, carbon dioxide production, oxygen consumption, and nonprotein substrate utilization. Energy expenditure does not necessarily increase with increasing energy intake independently of diet composition.