title: Branched-chain amino acid interactions with reference to amino acid requirements in adult men: valine metabolism at different leucine intakes.
abstract: We explored whether the oxidation of valine and by implication the physiological requirement for this amino acid are affected by changes in leucine intake over a physiological range. Six young adult men received, in random order, four L-amino acid-based diets for 5 d supplying either 20 or 10 mg valine.kg body wt-1.d-1, each in combination with 80 or 40 mg leucine.kg-1.d-1. On day 6 subjects were studied with an 8-h continuous intravenous infusion of [1-13C]valine (and [2H3]leucine) to determine valine oxidation in the fasted state (first 3 h) and fed state (last 5 h). Valine oxidation in the fasted state was similar among all diets but was lower (P less than 0.05) in the fed state for the 10 vs 20 mg valine.kg-1.d-1 intake. Leucine intake did not affect valine oxidation. Mean daily valine balance approximated +1.3 mg.kg-1.d-1 for the 20-mg intake and -1.6 mg.kg-1.d-1 for the 10-mg intake. These findings support our previously suggested mean valine requirement estimate of approximately 20 mg.kg-1.d-1.
authors.affiliation: Laboratory of Human Nutrition, Massachusetts Institute of Technology, Cambridge.
authors.forename: V
authors.initials: V
authors.lastname: Pelletier
authors.forename: L
authors.initials: L
authors.lastname: Marks
authors.forename: D A
authors.initials: DA
authors.lastname: Wagner
authors.forename: R A
authors.initials: RA
authors.lastname: Hoerr
authors.forename: V R
authors.initials: VR
authors.lastname: Young
mesh_terms: D000328:Adult; D002247:Carbon Isotopes; D003903:Deuterium; D005215:Fasting; D005502:Food; D006801:Humans; D007262:Infusions, Intravenous; D007532:Isoleucine / Q000097:blood; D007700:Kinetics; D007930:Leucine / Q000008:administration & dosage* / Q000097:blood; D008297:Male; D009751:Nutritional Requirements; D010084:Oxidation-Reduction; D014633:Valine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D007532:Isoleucine; D003903:Deuterium; D007930:Leucine; D014633:Valine