Effects of Whey Protein Supplementation on Sarcopenia and Frailty in Older Adults – A Narrative Review

Background and aims: Sarcopenia and frailty are common geriatric syndromes associated with loss of muscle mass, reduced strength, impaired physical performance, and increased vulnerability to adverse health outcomes. Whey protein has attracted attention as a high-quality, leucine-rich protein source with potential anabolic effects in older adults; however, its clinical impact is often difficult to isolate because many interventions combine whey protein with leucine, vitamin D, oral nutritional supplements, or resistance exercise. This narrative review summarizes and critically discusses current evidence on whey protein-containing interventions in older adults with sarcopenia, frailty, or related muscle dysfunction. Available studies suggest that such interventions may support improvements in muscle mass, particularly when combined with resistance training or additional anabolic nutrients. Effects on muscle strength and physical performance appear less consistent and are strongly influenced by exercise, baseline nutritional status, intervention duration, protein dose, and study population. Current evidence supports the use of whey protein primarily as part of multimodal sarcopenia management rather than as a consistently effective standalone intervention. Further well-designed clinical trials are needed to define optimal dosing strategies, identify responder profiles, and clarify the independent contribution of whey protein to functional outcomes in older adults.