Feasibility and Preliminary Effects of a Clinically Sustainable Low-Dose Protein Supplementation in Very Frail Nursing Home Residents

Background Aging is associated with loss of muscle mass and a higher risk of malnutrition, which adversely affects the quality of life in older adults. This study aimed to evaluate the effects of protein supplementation (14.8 g/day) in individuals aged ≥ 65 years with limited mobility on muscle mass (lean mass, fat-free mass index [FFMI]) and malnutrition indicators (Nutritional Risk Screening-2002 [NRS-2002], 7-point Subjective Global Assessment [SGA-7P], phase angle [PA]) and to assess the differences between feeding routes (oral vs. percutaneous endoscopic gastrostomy [PEG]). Methods In this study, 52 elderly residents of a long-term care facility (oral, n = 31; PEG, n = 13) received 14.8 g of protein supplement (including 1.3 g hydroxy methylbutyrate [HMB]) in addition to their usual diet, for 4 weeks. Their body composition was assessed using Bodystat Quadscan 4000. Nutritional status was evaluated using NRS-2002, SGA7P, and PA. Temporal changes were analyzed using the paired-samples t -test and differences between feeding routes using the McNemar test, McNemar–Bowker test, and independent-samples t -test. Results The increases in lean mass and FFMI were not statistically significant. Among malnutrition parameters, only the SGA-7P score significantly decreased. No significant changes were observed in NRS-2002 or PA. Furthermore, there were no group differences between oral and PEG feeding. Clinical observations indicated improved functional well-being with minimal physical activity. Conclusions Protein supplementation over 4 weeks did not significantly enhance muscle mass or most malnutrition indicators in older adults with limited mobility; however, it decreased SGA-7P scores. Feeding route also did not affect short-term outcomes. These findings highlight the feasibility of a clinically sustainable low-dose protein supplementation strategy and suggest that even modest protein top-ups may represent an initial step toward reducing malnutrition risk in very frail nursing-home residents.