Nutrients, Vol. 18, Pages 1449: The Effect of β-Hydroxy-β-Methyl Butyrate (HMB) upon Acute Fed-State Muscle Protein Turnover in Older Men and Women: A Randomized Double-Blind Controlled Crossover Clinical Trial
Nutrients doi: 10.3390/nu18091449
Authors:
Kenneth Smith
Haitham Abdullah
Supreeth Rudrappa
Amanda Gates
Jonathan Lewis
Iskandar Idris
Joseph J. Bass
Hannah Crossland
Daniel J. Wilkinson
Min Tian
Deborah S. Hustead
Geraldine E. Baggs
Suzette L. Pereira
Bethan E. Phillips
Philip J. Atherton
Background/Objectives: Anabolic resistance is thought to underlie muscle loss in sarcopenia. Here, we investigated the adjuvant role of beta-hydroxy-beta-methylbutyrate (HMB), a leucine metabolite, on the acute muscle anabolic response to oral protein supplementation in older adults. Methods: A total of 24 community-dwelling older adults (68.5 ± 0.6 years; 13 men, 11 women) were randomized in a cross-over double-blind design to 40 g whey protein (Control) or 40 g whey protein with 3 g calcium–HMB (HMB). Subjects received a primed constant infusion of 13C6 phenylalanine to assess muscle protein synthesis (MPS, by tracer incorporation in myofibrils) and muscle protein breakdown (MPB, via arterio-venous dilution) at baseline and post supplementation. Fasted and 3 h fed-state plasma HMB, aminoacidemia, rates of MPS, MPB, limb and muscle blood flow were measured. Results: In all subjects, both interventions displayed significant increases in MPS in response to feeding [fasted to 3 h-fed change (mean ± SEM, standard error of the mean). Males: control, +0.032 ± 0.006%.h−1; HMB, +0.023 ± 0.004%.h−1; females: control, +0.023 ± 0.006%.h−1; HMB, +0.038 ± 0.006%.h−1, p < 0.05]. In older women, the addition of HMB further enhanced the MPS response (fasted to 3 h-fed change, p = 0.0495) and area under the curve (p = 0.0364) versus protein alone. During the late-fed period, MPB significantly decreased in HMB versus control (p = 0.0298), and this was also observed when subjects were separated by sex (p = 0.0012). Conclusions: High-dose protein bolus feeding increased MPS in older adults. Surprisingly, 40 g whey did not maximize the anabolic response in older women, and HMB further increased the MPS feeding response to protein. HMB further suppressed the MPB feeding response over a longer period of time. Further work is needed to understand the apparent sexual dimorphic MPS response to high protein.
Background/Objectives: Anabolic resistance is thought to underlie muscle loss in sarcopenia. Here, we investigated the adjuvant role of beta-hydroxy-beta-methylbutyrate (HMB), a leucine metabolite, on the acute muscle anabolic response to oral protein supplementation in older adults. Methods: A total of 24 community-dwelling older adults (68.5 ± 0.6 years; 13 men, 11 women) were randomized in a cross-over double-blind design to 40 g whey protein (Control) or 40 g whey protein with 3 g calcium–HMB (HMB). Subjects received a primed constant infusion of 13C6 phenylalanine to assess muscle protein synthesis (MPS, by tracer incorporation in myofibrils) and muscle protein breakdown (MPB, via arterio-venous dilution) at baseline and post supplementation. Fasted and 3 h fed-state plasma HMB, aminoacidemia, rates of MPS, MPB, limb and muscle blood flow were measured. Results: In all subjects, both interventions displayed significant increases in MPS in response to feeding [fasted to 3 h-fed change (mean ± SEM, standard error of the mean). Males: control, +0.032 ± 0.006%.h−1; HMB, +0.023 ± 0.004%.h−1; females: control, +0.023 ± 0.006%.h−1; HMB, +0.038 ± 0.006%.h−1, p < 0.05]. In older women, the addition of HMB further enhanced the MPS response (fasted to 3 h-fed change, p = 0.0495) and area under the curve (p = 0.0364) versus protein alone. During the late-fed period, MPB significantly decreased in HMB versus control (p = 0.0298), and this was also observed when subjects were separated by sex (p = 0.0012). Conclusions: High-dose protein bolus feeding increased MPS in older adults. Surprisingly, 40 g whey did not maximize the anabolic response in older women, and HMB further increased the MPS feeding response to protein. HMB further suppressed the MPB feeding response over a longer period of time. Further work is needed to understand the apparent sexual dimorphic MPS response to high protein. Read More