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Energy intake, metabolic balance and growth in preterm infants fed formulas with different nonprotein energy
Gerardo Romera1, Josep Figueras, José Manuel Rodríguez-Miguélez
1Service of Neonatology, Integrated Unit of Pediatrics, Clínic and Sant Joan de Déu Hospitals, Institut d'Investigacions Biomèdiques August Pi i Sunyer, University of Barcelona, Barcelona, Spain. gerardorm@eremas.com
Insights
Excess nonprotein energy is stored as fat in preterm infants, regardless of whether it comes from fat or carbohydrates. High caloric and medium-chain triglyceride intake does not improve nitrogen retention in these infants.
Area of Science:
- Neonatal Nutrition
- Pediatric Gastroenterology
- Metabolic Research
Background:
- Preterm infants require specialized nutrition for optimal growth and development.
- Understanding energy metabolism and body composition is crucial for managing preterm infant nutrition.
- Nonprotein energy supplements are used to meet the high energy demands of preterm infants.
Purpose of the Study:
- To investigate the impact of different nonprotein energy supplements on metabolic and energy balances in preterm infants.
- To determine the effects of these supplements on growth and body composition, specifically fat and protein accretion.
- To compare energy utilization and storage in preterm infants fed standard formula versus formula with energy supplements.
Main Methods:
- A study involving growing preterm infants (birth weight < 1,500 g, gestational age < 31 weeks).
- Infants were fed standard preterm formula or formula with three different nonprotein energy supplements (medium-chain triglyceride and dextrinomaltose in varying ratios).
- Measurements included energy expenditure, urinary nitrogen excretion, energy intake, oxidation, output, and body composition analysis.
Main Results:
- Fat accretion correlated directly with fat intake across the supplemented groups.
- Infants receiving higher energy intake showed a significantly higher percentage of fat in their weight gain compared to the standard intake group.
- Skinfold thickness measurements supported the findings of increased fat deposition in supplemented groups.
Conclusions:
- Excess nonprotein energy, irrespective of its source (fat or carbohydrate), is stored as body fat in preterm infants.
- Increased caloric and medium-chain triglyceride intake did not enhance nitrogen retention in healthy, growing preterm infants.
- Nutritional strategies for preterm infants should consider the partitioning of energy between fat storage and other metabolic processes.
Objective:
To study metabolic and energy balances, growth and composition of increased body mass in healthy preterm infants fed control formula or control formula with three different nonprotein energy supplements.
Patients And Methods:
Growing preterm infants (birth weight < 1,500 g and gestational age < 31 weeks) were fed standard preterm formula (control group) or the same formula enriched with three different nonprotein energy supplements. An energy supplement of 23 kcal/kg/day was achieved by adding medium-chain triglyceride and dextrinomaltose in three different caloric ratios: 33:66 in group A, 66:33 in group B, and 85:15 in group C. Energy balance was determined by open-circuit continuous (5-6 hours) measurements of energy expenditure, with simultaneous measurement of 24-hour urinary nitrogen excretion. Metabolic balance was determined by measurements of energy intake, energy oxidation, and energy output in urine and stool. The composition of body mass accretion was determined as the accretion of fat and protein in the total weight gain.
Results:
The fat accretion (4.9, 5.9, 6.2, and 3.8 g/kg/day in groups A, B, C and D, respectively) correlated directly with fat intake. Infants receiving standard energy intake had a fat percentage of weight gain significantly lower (28%) than that of the high-energy intake groups (31%, 40%, and 38% in groups A, B, and C, respectively). This difference corresponded to the results obtained from skinfold thickness measurements.
Conclusions:
Excess nonprotein energy is stored as fat regardless of its source (fat or carbohydrate). High caloric and medium-chain triglyceride intake in otherwise healthy growing preterm infants does not promote nitrogen retention.
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