title: Year-long changes in protein metabolism in elderly men and women supplemented with a nutrition cocktail of beta-hydroxy-beta-methylbutyrate (HMB), L-arginine, and L-lysine.
abstract: BACKGROUND
  A major contributing factor to the loss of mobility in elderly people is the gradual and continuous loss of lean body mass.
  
  
  OBJECTIVE
  To determine whether supplementation of an amino acid cocktail daily for 1 year could improve the age-associated changes in protein turnover and lean body mass in elderly people.
  
  
  METHODS
  Elderly (76+/-1.6 years) women (n=39) and men (n=38) were recruited for a double-blinded controlled study. Study participants were randomly assigned to either an isonitrogenous control-supplement (n=37) or a treatment-supplement (HMB/Arg/Lys) consisting of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-lysine (n=40) for the 1-year study. Lean tissue mass was measured using both bioelectrical-impedance analysis (BIA) and dual energy x-ray absorptiometry (DXA). Rates of whole-body protein turnover were estimated using primed/intermittent oral doses of 15N-glycine.
  
  
  RESULTS
  In subjects taking the HMB/Arg/Lys supplement, lean tissue increased over the year of study while in the control group, lean tissue did not change. Compared with control, HMB/Arg/Lys increased body cell mass (BIA) by 1.6% (P=.002) and lean mass (DXA) by 1.2% (P=.05). The rates of protein turnover were significantly increased 8% and 12% in the HMB/Arg/Lys-supplemented group while rates of protein turnover decreased 11% and 9% in the control-supplemented subjects (P<.01), at 3 and 12 months, respectively.
  
  
  CONCLUSIONS
  Consumption of a simple amino acid-related cocktail increased protein turnover and lean tissue in elderly individuals in a year-long study.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, USA.
authors.forename: Shawn
authors.initials: S
authors.lastname: Baier
authors.forename: Darcy
authors.initials: D
authors.lastname: Johannsen
authors.forename: Naji
authors.initials: N
authors.lastname: Abumrad
authors.forename: John A
authors.initials: JA
authors.lastname: Rathmacher
authors.forename: Steven
authors.initials: S
authors.lastname: Nissen
authors.forename: Paul
authors.initials: P
authors.lastname: Flakoll
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001120:Arginine / Q000009:adverse effects / Q000627:therapeutic use*; D001823:Body Composition / Q000187:drug effects*; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008239:Lysine / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010349:Patient Compliance; D011506:Proteins / Q000378:metabolism*; D011795:Surveys and Questionnaires; D014631:Valerates / Q000009:adverse effects / Q000627:therapeutic use*
chemical_list: D011506:Proteins; D014631:Valerates; C004961:beta-hydroxyisovaleric acid; D001120:Arginine; D008239:Lysine