Protein

Research summary

• A foundational meta-analysis and meta-regression established that protein supplementation meaningfully augments resistance-training-induced gains in muscle mass and strength in healthy adults, and this has been extensively replicated in older adults with sarcopenia specifically, including network meta-analyses comparing different protein types and dosing strategies.
• Meta-analyses in postmenopausal women and community-dwelling older adults with sarcopenia both confirm the pattern, and a broader synthesis links higher protein intake to better physical function in older age even without formal resistance training.
• On safety, meta-analyses of high-versus-normal protein intake found no evidence of harm to kidney function in people without pre-existing kidney disease, while a separate body of evidence in diagnosed nephropathy supports the opposite approach (protein restriction) for that specific population.
• This is one of the more consistently and rigorously evidenced supplements for a clearly defined outcome — preserving muscle with aging.