title: Effect of β-hydroxy-β-methylbutyrate (HMB) on lean body mass during 10 days of bed rest in older adults.
abstract: BACKGROUND
  Loss of muscle mass due to prolonged bed rest decreases functional capacity and increases hospital morbidity and mortality in older adults.
  
  
  OBJECTIVE
  To determine if HMB, a leucine metabolite, is capable of attenuating muscle decline in healthy older adults during complete bed rest.
  
  
  METHODS
  A randomized, controlled, double-blinded, parallel-group design study was carried out in 24 healthy (SPPB ≥ 9) older adult subjects (20 women, 4 men), confined to complete bed rest for ten days, followed by resistance training rehabilitation for eight weeks. Subjects in the experimental group were treated with HMB (calcium salt, 1.5 g twice daily - total 3 g/day). Control subjects were treated with an inactive placebo powder. Treatments were provided starting 5 days prior to bed rest till the end rehabilitation phase. DXA was used to measure body composition.
  
  
  RESULTS
  Nineteen eligible older adults (BMI: 21-33; age: 60-76 year) were evaluable at the end of the bed rest period (Control n = 8; Ca-HMB n = 11). Bed rest caused a significant decrease in total lean body mass (LBM) (2.05 ± 0.66 kg; p = 0.02, paired t-test) in the Control group. With the exclusion of one subject, treatment with HMB prevented the decline in LBM over bed rest -0.17 ± 0.19 kg; p = 0.23, paired t-test). There was a statistically significant difference between treatment groups for change in LBM over bed rest (p = 0.02, ANOVA). Sub-analysis on female subjects (Control = 7, HMB = 8) also revealed a significant difference in change in LBM over bed rest between treatment groups (p = 0.04, ANOVA). However, differences in function parameters could not be observed, probably due to the sample size of the study.
  
  
  CONCLUSIONS
  In healthy older adults, HMB supplementation preserves muscle mass during 10 days of bed rest. These results need to be confirmed in a larger trial.
authors.affiliation: Center for Translational Research in Aging & Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, USA. Electronic address: nep.deutz@tamu.edu.
authors.forename: Nicolaas E P
authors.initials: NE
authors.lastname: Deutz
authors.forename: Suzette L
authors.initials: SL
authors.lastname: Pereira
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Hays
authors.forename: Jeffery S
authors.initials: JS
authors.lastname: Oliver
authors.forename: Neile K
authors.initials: NK
authors.lastname: Edens
authors.forename: Chris M
authors.initials: CM
authors.lastname: Evans
authors.forename: Robert R
authors.initials: RR
authors.lastname: Wolfe
mesh_terms: D015502:Absorptiometry, Photon; D000368:Aged; D000375:Aging; D001510:Bed Rest / Q000009:adverse effects*; D001823:Body Composition; D019587:Dietary Supplements / Q000009:adverse effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D024510:Muscle Development; D009124:Muscle Proteins / Q000096:biosynthesis / Q000378:metabolism; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000378:metabolism; D009142:Musculoskeletal Physiological Phenomena; D055070:Resistance Training; D055948:Sarcopenia / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control* / Q000534:rehabilitation; D014631:Valerates / Q000009:adverse effects / Q000627:therapeutic use*; D051598:Whole Body Imaging
chemical_list: D009124:Muscle Proteins; D014631:Valerates; C004961:beta-hydroxyisovaleric acid
keywords: Beta-hydroxy-beta-methylbutyrate; Body composition; HMB; LBM; Lean body mass; Muscle; Protein synthesis; SPPB; Short Physical Performance Battery score