Abstract
Introduction: Sarcopenia constitutes the progressive loss of muscle mass, strength and function, most commonly in adults ≥60 years old. Associated adverse outcomes include immobility, loss of independence, falls, fractures and increased mortality. Predisposing risk factors include aging, comorbid disease and malnutrition. Malnutrition is common amongst older adults and low protein intake is strongly associated with sarcopenia. Dietary protein intake as a risk factor for sarcopenia and subsequent fracture risk is poorly understood. This systematic review aimed to ascertain the relationship and impact of protein intake in sarcopenia and associated fracture risk.
Methods: MEDLINE and EMBASE searches were conducted. Eligibility criteria: adults ≥65 years of age with sarcopenia, studies focussing on protein intake with/without other interventions and full text availability. Measurable outcomes included appendicular lean mass (ALM), appendicular skeletal mass (ASM) or skeletal muscle index (SMI), hand grip strength (HGS) and chair stands, bone mineral density (BMD), falls or fracture incidence.
Results: 26 studies were included. Protein intervention evidenced positive but inconsistent results on BMD. Protein intervention had positive effects on all 3 domains of sarcopenia. Lean muscle mass (standardised mean difference (SMD): 0.0975; 95% confidence interval (CI) 0.0972-0.2922; p=0.2815; I²=0.0%), HGS (SMD: 0.2531; 95% CI 0.0785-0.4276; p=0.0095; I²=0.0%) and chair stands (SMD: 0.4658; 95% CI 0.1197-0.8120; p=0.0181; I²=21.2%). ASM and BMD showed positive correlation. Higher protein intake was associated with significantly higher ASM/lower decline but was inconsistent. Low protein intake was reported in fallers and/or fracture positive patients but was inconsistent. Significantly higher fracture risk and falls incidences was reported in sarcopenic patients with or without osteoporosis versus non-sarcopenic/osteoporotic participants.
Conclusion: Protein intervention had positive effects across all 3 domains of sarcopenia but was significant in strength and functionality indicating the greatest impact was on muscle quality. Further research is recommended to clearly establish the impact on fracture risk.
Comments
Forward plan
Hello. Thank you for the detailed work here. How would you propose that this information should be taken forward in order to better assess impact of protein intake on bone health?
Forward plan
Hello,
Thank you for your interest and question regarding the research. We would recommend further research via a standardised, longitudinal randomised-control trial. This would better clarify the effects of protein intervention on BMD for which there is currently limited evidence available, particularly when applied to sarcopenic populations. Additionally, research exploring the effect of different protein types such as plant, dairy and animal could help establish more comprehensive nutritional guidance.
Thank you for your poster,…
Thank you for your poster, were you able to ascertain any level of detail the forms of protein consumed?
Forms of protein consumed
Hello,
Thank you for your question. Protein interventions predominantly used whey protein supplementation. One multi-arm study also looked at soy protein and whey-soy combinations. Two studies didn't disclose the specific form of protein intervention used.
Hello, Did papers give…
Hello,
Did papers give evidence of the amount of protein in each category (e.g. grams)?
Protein Amount
Thanks for your question. On review of the identified papers they used different proteins and different amounts of supplementation.
Most supplements were between 30g-40g additional protein per day as an oral nutritional supplement.
Protein amount
Hello,
Thank you for your question. The amount of protein supplementation used within intervention groups varied between papers. Papers focussing on the effects of protein intervention on BMD reported interventions of 20-80g of protein. Papers reporting the effects of protein intervention on lean muscle mass and hand grip strength used interventions of 16-127g. Papers reporting the effects of protein intervention on chair stands reported interventions of 20-30g of protein.