One hundred twenty-four patients aged 50–70 years with minor or mild knee osteoarthritis and sarcopenia were randomized to receive either high plant protein/peptide supplementation (n=63) or placebo (n=61) for 12 weeks. The primary outcome was the change in the Short Physical Performance Battery (SPPB) score. Secondary outcomes included changes in grip strength, skeletal muscle mass index (SMI), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, bone mineral density, and health quality scores. After 12 weeks, the experimental group showed significant improvements in SPPB score (P<0.0001), grip strength (P<0.0001), and SMI (P<0.0001) compared to the placebo group. WOMAC scores decreased significantly, indicating reduced pain and stiffness. Overall, the study demonstrated that plant protein/peptide supplementation improves physical performance, muscle strength, and osteoarthritis symptoms, suggesting it is a beneficial nutritional intervention for elderly individuals with sarcopenia and mild osteoarthritis