title: Oral citrulline does not affect whole body protein metabolism in healthy human volunteers: results of a prospective, randomized, double-blind, cross-over study.
abstract: OBJECTIVE
  Citrulline increases protein synthesis during refeeding in rodents with short bowel syndrome, aging and malnutrition, and improves nitrogen balance in fed healthy humans. The aim of the current study therefore was to determine whether citrulline had affected protein metabolism in healthy volunteers.
  
  
  METHODS
  In a randomized, double-blind, cross-over study, 12 healthy adults received a 5-h intravenous infusion of L-[1-(13)C]-leucine in the post-absorptive state, after a 7-day oral supplementation with 0.18 g/kg/day citrulline, or an iso-nitrogenous placebo. Treatment order was randomized, treatment periods were separated by 13-day wash out. Leucine appearance rate (Ra) was determined from plasma [1-(13)C]-keto-iso-caproate enrichment and leucine oxidation from expired (13)CO(2), and nitrogen balance was estimated from 6-h urinary urea excretion.
  
  
  RESULTS
  Compared with placebo, oral citrulline supplementation increased plasma citrulline, arginine and ornithine concentrations, but failed to affect albumin, transthyretin, free insulin and insulin-like growth factor (IGF)-1 plasma concentrations, urinary nitrate excretion, or nitrogen balance. Citrulline supplementation did not alter leucine Ra, leucine oxidation, nor whole-body protein synthesis.
  
  
  CONCLUSIONS
  In healthy, well nourished volunteers, oral citrulline increases plasma citrulline and arginine availability but does not affect whole-body protein kinetics in the post-absorptive state.
authors: Service d'Hépato-gastro-entérologie et Assistance Nutritionnelle, CHU de Nantes, France.
authors: Ronan
authors: R
authors: Thibault
authors: Laurent
authors: L
authors: Flet
authors: Fabienne
authors: F
authors: Vavasseur
authors: Marie
authors: M
authors: Lemerle
authors: Véronique
authors: V
authors: Ferchaud-Roucher
authors: Denis
authors: D
authors: Picot
authors: Dominique
authors: D
authors: Darmaun
mesh_terms: D000293:Adolescent; D000328:Adult; D000596:Amino Acids / Q000097:blood; D002956:Citrulline / Q000008:administration & dosage*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011506:Proteins / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D011506:Proteins; D002956:Citrulline