This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Beckett, P. R. Articles by Copeland, K. C. Search for Related Content PubMed PubMed Citation Articles by Beckett, P. R. Articles by Copeland, K. C.

The Efficiency of Dietary Protein Utilization Is Increased during Puberty¹

Department of Pediatrics, Endocrinology and Metabolism Section, Texas Children’s Hospital and U.S. Department of Agriculture, Agricultural Research Service, Children’s Nutrition Research Center, Baylor College of Medicine, Houston, Texas 77030

Address all correspondence and requests for reprints to: Philip R. Beckett, Ph.D., Texas Children’s Hospital, 6621 Fannin, MC 3–2351, Houston, Texas 77030. E-mail: pbeckett{at}bcm.tmc.edu

We investigated whether the efficiency of dietary protein utilization for growth increases during the pubertal growth spurt in both nondiabetic and diabetic subjects.

We measured leucine oxidation and retention (intake minus oxidation) in orally fed nondiabetic (n = 9) and diabetic (n = 9) human subjects, aged 7–17 yr. Eight subjects were Tanner stage I, and 10 were Tanner stages III–V; groups were not matched for gender. After 3 days of consuming a diet containing approximately 1 g/kg · day protein, subjects drank a commercial liquid nutrition formula, containing L-[1-¹³C]leucine, every 30 min for a total of 6 h to provide 1 g protein/kg · day. Isotopic enrichment of CO₂ was used to calculate the fractional leucine oxidation rate and, together with -ketoisocaproate isotopic enrichment, to calculate total leucine oxidation.

Leucine oxidation rates decreased with puberty in both nondiabetic subjects (36.0 ± 10.4 vs. 23.9 ± 4.2 µmol/kg fat-free mass (FFM) · h, prepubertal and pubertal, respectively; P < 0.05) and diabetic (33.6 ± 4.9% vs. 27.3 ± 3.4 µmol/kg FFM · h, prepubertal and pubertal, respectively; P < 0.1) subjects. Leucine retention increased with puberty in both nondiabetic (0.27 ± 3.2 vs. 15.7 ± 5.3 µmol/kg FFM · h, prepubertal and pubertal, respectively; P < 0.001) and diabetic (1.9 ± 4.9 vs. 13.2 ± 4.4 µmol/kg FFM · h, prepubertal and pubertal subjects, respectively; P < 0.05) subjects. The data suggest that the pubertal growth spurt is associated with a marked increase in the efficiency of dietary protein utilization for growth.