title: Vitamin D status affects strength gains in older adults supplemented with a combination of β-hydroxy-β-methylbutyrate, arginine, and lysine: a cohort study.
abstract: BACKGROUND
  Older adults supplemented for 1 year with β-hydroxy-β-methylbutyrate, arginine, and lysine (HMB/ARG/LYS) were previously shown to have significant gains in fat-free mass (FFM) but not muscular strength.
  
  
  OBJECTIVE
  Recently, increasing levels of serum vitamin D have been associated with an increase in muscle function, particularly in the elderly. To determine if vitamin D status may have limited strength gain in participants supplemented with HMB/ARG/LYS, the authors performed post hoc analysis of strength based on the participants' vitamin D status.
  
  
  METHODS
  Elderly (age 76.0 ± 1.6 years) adults were recruited for a double-blinded, controlled study and were randomly assigned to either an isonitrogenous control (n = 37) or HMB/ARG/LYS (n = 40) for the yearlong study. Participants were further segregated based on their vitamin D status of either <30 or ≥30 ng 25OH-vitD(3)/mL serum, and an analysis was performed on the 4 cohorts.
  
  
  RESULTS
  Regardless of vitamin D status, HMB/ARG/LYS resulted in significantly increased FFM (P < .02), but only in those with vitamin D status ≥30 ng 25OH-vitD(3)/mL was there a significant increase in strength with HMB/ARG/LYS (P < .01). Control-supplemented participants, regardless of vitamin D status, and the HMB/ARG/LYS-supplemented participants with vitamin D status <30 ng 25OH-vitD(3) failed to show improvements in strength.
  
  
  CONCLUSIONS
  The nutrient cocktail of HMB/ARG/LYS alone was effective in increasing muscle mass regardless of vitamin D status, but accompanying strength increases were observed only when participants also had adequate vitamin D status indicating a synergistic effect between the HMB/ARG/LYS and vitamin D.
authors.affiliation: Metabolic Technologies, Inc, Iowa State University Research Park, Ames, USA.
authors.forename: John C
authors.initials: JC
authors.lastname: Fuller
authors.forename: Shawn
authors.initials: S
authors.lastname: Baier
authors.forename: Paul
authors.initials: P
authors.lastname: Flakoll
authors.forename: Steven L
authors.initials: SL
authors.lastname: Nissen
authors.forename: Naji N
authors.initials: NN
authors.lastname: Abumrad
authors.forename: John A
authors.initials: JA
authors.lastname: Rathmacher
mesh_terms: D000368:Aged; D000596:Amino Acids / Q000494:pharmacology*; D001120:Arginine / Q000494:pharmacology; D001825:Body Fluid Compartments / Q000187:drug effects; D002087:Butyrates / Q000494:pharmacology*; D015331:Cohort Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008239:Lysine / Q000494:pharmacology; D008297:Male; D053580:Muscle Strength / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D000596:Amino Acids; D002087:Butyrates; D014807:Vitamin D; D001120:Arginine; C104450:25-hydroxyvitamin D; D008239:Lysine