The Impact of Oral Whey Protein and Yeast Protein Supplementation for 6 Months on Skeletal Muscle Mass, Strength, and...

This study aimed to evaluate the effects of 6-month daily supplementation with whey protein (WP) or yeast protein (YP) on anthropometric measurements, laboratory parameters, skeletal muscle mass, muscle strength, and physical function in Chinese older adults. In this randomized controlled trial, 92 participants were assigned to WP (n = 31), YP (n = 30), or control (n = 31) groups. At baseline and 24 weeks, we assessed: anthropometrics (weight, BMI, and waist/calf circumference); laboratory parameters (ALT, TG, TC, creatinine, urea, hemoglobin, and FBG); appendicular skeletal muscle mass (index); handgrip strength; and physical function (6-m walk speed, chair stand test, SPPB). Habitual diet and activity were maintained. Anthropometrics: Compared to controls, both protein groups significantly reduced body weight (WP: -5.4 kg; YP: -0.9 kg; both p < 0.05). Laboratory Parameters: TC decreased significantly from baseline in both WP (-0.15 mmol/L) and YP (-0.18 mmol/L) groups (p < 0.05). Muscle mass and strength: No intergroup differences were found in changes of ASM or handgrip strength (p > 0.05). Physical function: Both intervention groups showed greater improvement in 6-m walk speed and SPPB scores versus control (p < 0.05). The mean increase in SPPB score in the YP group (0.9 points) reached the threshold for a minimal clinically important difference. Six-month supplementation with either WP or YP improved body weight, cholesterol, and physical function in Chinese older adults, with comparable effects between the two protein sources. YP may serve as a viable alternative to WP for enhancing functional status, a finding with potential clinical relevance.