The recommended dietary allowance for protein is sufficient to maintain lean body mass (LBM) in older men with physical function limitations, and protein intake exceeding the recommended dietary allowance does not increase LBM or well-being measures, a recent study found. In this randomized clinical trial, participants included 92 functionally limited men aged ≥65 years with usual protein intake ≤0.83 g/kg/d within the recommended dietary allowance (RDA). They were randomized for 6 months to controlled diets with 0.8 g/kg/d of protein plus placebo, 1.3 g/kg/d of protein plus placebo, 0.8 g/kg/d of protein plus testosterone enanthate (100 mg weekly), or 1.3 g/kg/d of protein plus testosterone. The primary outcome was change in LBM. Researchers found:
- Changes from baseline in LBM and appendicular and trunk lean mass, as well as muscle strength and power, walking speed and stair-climbing power, health-related quality of life, fatigue, and well-being, did not differ between men assigned to 0.8 vs 1.3 g/kg/d of protein regardless of whether they received testosterone or placebo.
- Fat mass decreased in participants given higher protein but did not change in those given the RDA.
Bhasin S, Apovian CM, Travison TG, et al. Effect of protein intake on lean body mass in functionally limited older men. A randomized clinical trial. [Published online ahead of print March 12, 2018]. JAMA Intern Med. doi:10.1001/jamainternmed.2018.0008.