148 Branched Chain Amino Acid Requirements for Term Neonates

Abstract

Background: Dietary intake should meet the requirement to obtain an optimal growth and neurodevelopment in the neonate. The essential branched chain amino acids (BCAAs), leucine, isoleucine and valine, are mainly used for incorporation into body protein. Current recommended BCAA requirements for infants 0-6 months (respectively 156, 88 and 87 mg•kg−1•d−1, ratio 1.8:1:1) are based on the amino acid content of human milk. However, human milk fluctuates in composition during lactation and even during a feeding, while milk consumption rate varies widely as well. Questions remain on the validity to use mean amino acid composition of human milk to determine requirements. Objectives: To quantify the requirement of leucine, isoleucine and valine in term neonates using the Indicator Amino Acid Oxidation method. Design: Enterally fed term infants received randomly graded intakes of leucine (15-500 mg•kg−1•d−1), isoleucine (5-216 mg•kg−1•d−1) and valine (5-236 mg•kg−1•d−1). Breath samples containing 13CO2 were collected during L-[1-13C]phenylalanine (indicator amino acid) administration, measured by isotope ratio mass spectrometry and analysed using a biphasic regression crossover analysis. Results: 83 term Asian neonates (birth weight: 3.29 ± 0.4 kg, gestational age: 39.4 ± 1.3 wks, postnatal age: 12.6 ± 5.1 d) were included. The mean requirement (at breakpoint) for leucine, isoleucine and valine was respectively 140, 105 and 110 mg•kg−1•d−1 and the upper 95% confidence interval was 240, 152 and 165 mg•kg−1•d−1. Conclusion: The requirements of the individual BCAAs are almost twice the current recommendations. A Leu:lle:Val ratio of 1.3:1:1 is more appropriate in term formula.