title: Effects of 6-month supplementation with β-hydroxy-β-methylbutyrate, glutamine and arginine on vascular endothelial function of older adults.
abstract: OBJECTIVE
  Vascular endothelial function declines with advancing age, due in part to increased oxidative stress and inflammation, and this age-related vascular dysfunction has been identified as an independent risk factor for cardiovascular diseases. This double-blind, placebo-controlled trial investigated the effects of a dietary supplement containing β-hydroxy-β-methylbutyrate (HMB), glutamine and arginine on endothelial-dependent vasodilation of older adults.
  
  
  METHODS
  A total of 31 community-dwelling men and women aged 65-87 years were randomly assigned to two groups. The treatment group received two doses of the supplement daily (totaling 3 g HMB, 14 g glutamine and 14 g arginine) for 6 months, whereas the control group received an isocaloric placebo. At baseline and week 24, vascular endothelial function was measured by flow-mediated dilation of the brachial artery, and fasting blood samples were obtained to measure high-sensitivity C-reactive protein (hsCRP) and tumor necrosis factor-α (TNF-α).
  
  
  RESULTS
  Paired sample t-tests revealed a 27% increase in flow-mediated dilation among the treatment group (P=0.003), whereas no change was observed in the placebo group (P=0.651). Repeated-measures analysis of variance verified a significant time by group interaction (P=0.038). Although no significant changes were observed for hsCRP or TNF-α, a trend was observed for increasing hsCRP among the placebo group only (P=0.059).
  
  
  CONCLUSIONS
  These results suggest that dietary supplementation of HMB, glutamine and arginine may favorably affect vascular endothelial function in older adults. Additional studies are needed to elucidate whether reduced inflammation or other mechanisms may underlie the benefits of supplementation.
authors: Department of Human Nutrition, University of Alabama, Tuscaloosa, AL, USA.
authors: A C
authors: AC
authors: Ellis
authors: Department of Human Nutrition, University of Alabama, Tuscaloosa, AL, USA.
authors: M
authors: M
authors: Patterson
authors: School of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL, USA.
authors: T
authors: T
authors: Dudenbostel
authors: School of Medicine, Division of Cardiovascular Disease, University of Alabama at Birmingham, Birmingham, AL, USA.
authors: D
authors: D
authors: Calhoun
authors: Department of Nutrition Sciences, University of Alabama at Birmingham, Birmingham AL, USA.
authors: B
authors: B
authors: Gower
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000502:physiology*; D001120:Arginine / Q000008:administration & dosage*; D001916:Brachial Artery / Q000502:physiology; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000209:etiology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D005215:Fasting / Q000097:blood; D005260:Female; D005973:Glutamine / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D014631:Valerates / Q000008:administration & dosage*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D014409:Tumor Necrosis Factor-alpha; D014631:Valerates; D005973:Glutamine; C004961:beta-hydroxyisovaleric acid; D002097:C-Reactive Protein; D001120:Arginine