Threonine kinetics at graded threonine intakes in young men

• Published in: The American journal of clinical nutrition Vol. 43; no. 5; pp. 795 - 802
• Main Authors: Zhao, XH, Wen, ZM, Meredith, CN, Matthews, DE, Bier, DM, Young, VR
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.05.1986; American Society for Clinical Nutrition
• Subjects: 1-13-threonine; Adolescent; Adult; amino acid kinetics; amino acid requirements; Biological and medical sciences; Diet; DIETA; Fundamental and applied biological sciences. Psychology; Glycine - blood; HOMBRES; HOMME; Humans; Infusions, Parenteral; Kinetics; Male; METABOLISME; METABOLISMO; Metabolisms and neurohumoral controls; Nitrogen metabolism. Proteins. Glycoproteins. Nucleic acids. Collagen; OXIDACION; OXYDATION; PLASMA SANGUIN; PLASMA SANGUINEO; plasma threonine; REGIME ALIMENTAIRE; stable isotope; THREONINE; Threonine - administration & dosage; Threonine - blood; TREONINA; Vertebrates: anatomy and physiology, studies on body, several organs or systems; young men; plasma threonine; Threonine; amino acid kinetics; amino acid requirements; young men; 1-13-threonine; stable isotope; Human; Nutrient requirement; Food intake; Aminoacid; Kinetics; Metabolism; Feeding; Tracers
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/43.5.795

A study was undertaken in eight healthy young men to examine the effects of varying intakes of threonine on plasma free threonine concentrations and threonine kinetics, using a 3 h constant intravenous infusion of L-[1-13C]threonine. Subjects consumed diets based on an L-amino acid mixture, in which the quality of threonine was reduced every 7 days. On the last day of each diet period, determinations of plasma threonine flux and threonine oxidation were carried out while subjects consumed small meals, each supplying 1/12 dairy intake, at hourly intervals. Threonine oxidation rates fell with reduced threonine intake, reaching a relatively constant level at intakes of 20 mg·kg−1·day−1 and below. These metabolic data are discussed in relation to the currently established value of 7 mg·kg−1·day−1 as the upper range of the threonine requirement for healthy young adults. It is concluded that actual threonine requirements may be considerably higher for this age group.