HMB Supplementation for Shoulder Fracture with Immobilization
Yes, beta-hydroxy-beta-methylbutyrate (HMB) supplementation at 3 g/day is advisable for a shoulder fracture requiring several weeks of immobilization, as it significantly reduces muscle loss during bedrest and accelerates recovery.
Evidence from Perioperative Guidelines
The 2020 ESPEN expert group on perioperative nutrition provides the strongest guideline-level evidence supporting HMB use during immobilization 1. A randomized placebo-controlled trial demonstrated that HMB supplementation during 10 days of bedrest resulted in:
- Significant reduction in muscle loss during the immobilization period 1
- Increased muscle mass gain during the 8-week rehabilitation phase for both total lean mass and total leg lean mass 1
- Preservation of muscle strength throughout the immobilization period 1
This is particularly relevant because just 7 days of bedrest causes approximately 1 kg loss of lean leg muscle mass in older adults, affecting both type I and type II muscle fibers 1. The initial loss of strength occurs rapidly during immobilization and plateaus after approximately 30 days 1.
Specific Evidence in Orthopedic Fracture Patients
A 2016 randomized controlled trial specifically examined older female patients with hip fractures receiving CaHMB (3 g), vitamin D (1000 IU), and protein (36 g) supplementation 2. Results showed:
- Significantly shorter wound-healing period compared to controls 2
- 81.3% of supplemented patients were mobile on days 15 and 30 versus only 26.7% in controls (p=0.001) 2
- Significantly higher muscle strength at day 30 2
- Reduced bed dependence and related complications 2
Dosing and Timing Recommendations
Standard dosing protocol:
- 3 g/day total dose - this is the evidence-based amount consistently shown effective 3, 4, 5
- Divided into three 1-g doses taken at breakfast, lunch, and dinner for chronic supplementation 5
- Begin immediately and continue for at least 2 weeks, ideally throughout the entire immobilization period 3, 5
Two formulation options exist:
- Calcium HMB (HMB-Ca): take 60-120 minutes before physical therapy sessions 5
- Free acid HMB (HMB-FA): take 30-60 minutes before physical therapy sessions, though evidence for superiority is insufficient 3, 5
Mechanisms Supporting Use
HMB works through multiple pathways particularly relevant to immobilization 3, 5:
- Inhibits muscle protein breakdown (proteolysis) 3
- Increases protein synthesis 3
- Reduces inflammation associated with muscle damage 5
- Decreases oxidative stress 5
- Promotes cellular cholesterol synthesis via β-hydroxy-β-methylglutaryl-CoA production 5
Safety Profile
HMB has an unequivocal safety profile with chronic consumption safe in both young and old populations 3, 4. A 2025 meta-analysis of 11 RCTs with 575 surgical patients confirmed safety while demonstrating significant reductions in hospital length of stay (MD -0.90 days, p=0.05) and postoperative complications (RR 0.50, p=0.003) 6.
Rehabilitation Considerations for Shoulder Fractures
The EULAR/EFORT 2017 guidelines specify that following shoulder fracture treatment, range-of-motion exercises should begin within the first postoperative days 1. Above chest level activities should be restricted until fracture healing is evident, but overly aggressive physical therapy may increase fixation failure risk 1. HMB supplementation complements this approach by preserving muscle mass and strength during the necessary restriction period.
Important Caveats
- Do not combine HMB with creatine for EIMD reduction, as co-administration does not appear effective 5
- Ensure adequate protein intake exceeding 1 g/kg body weight/day in addition to HMB 1
- Consider combining with vitamin D (1000 IU) and additional protein (36 g) as done in the orthopedic fracture trial 2
- While essential amino acid mixtures normalize muscle protein synthesis, they have not shown effects on skeletal muscle loss or function, making HMB the superior choice 1
The evidence strongly supports HMB supplementation at 3 g/day throughout the immobilization period for shoulder fractures, with particular benefit for older adults who experience more rapid muscle loss during bedrest 1.