Protein intake to ameliorate changes in muscle strength, mass and function in hospitalised older adults: a systematic review

Introduction 

Falls in older adults are a leading cause of injury, hospitalisation and loss of independence, with sarcopenia a major modifiable risk reduction factor. Acute illness and hospitalisation accelerate muscle loss, further increasing risk of falls. Adequate protein intake and resistance exercise are central to maintaining muscle mass and function. This systematic review examined how protein type, dose and timing affect muscle mass, strength and function in hospitalised or recently discharged older adults.

Methods

A systematic review and meta-analysis of randomised controlled trials was conducted according to PRISMA guidelines (PROSPERO CRD42024576807). Five databases were searched. Included studies recruited adults aged ≥65 years in hospital or within one week of discharge and evaluated protein-based interventions (including, oral nutritional supplements (ONS), whey protein, leucine, β-hydroxy β-methylbutyrate (HMB), or food-first). Outcomes included muscle mass, muscle strength and physical function. . Meta-analysis was undertaken where outcomes from ≥3 clinically comparable studies were available.

Results

Thirty trials (n = 2,605; mean age ~80 years) were included. HMB-enriched supplements significantly improved handgrip strength compared with control (mean difference 1.20 kg, 95% CI 0.90 to 1.51), although findings were strongly influenced by one large study. Leucine-enriched whey protein showed potential benefits in individual studies, but pooled effects were not statistically significant and heterogeneity was substantial. Other interventions produced inconsistent results, particularly for muscle mass.

Conclusions

Protein supplementation, particularly when enriched with leucine or HMB, enhances muscle strength and physical function in older adults recovering from acute illness. Given the central role of strength and mobility in falls prevention, integrating optimised protein strategies into rehabilitation pathways may help improve recovery and reduce post-hospital falls risk. Large, high-quality randomised controlled trials are needed to refine dosing, timing and combinations with exercise.