Effect of Polyphenol-Rich Diet Combined with Leucine, Vitamin D3, and Magnesium Supplementation on Self-Reported Mobility and Health Perception in Adults at Risk of Sarcopenia: A 3-Months Quasi-Experimental Study

Background: Sarcopenia is characterized by progressive muscle weakness, impaired physical function, and reduced quality of life. Multimodal strategies combining rehabilitation and nutritional support that influence gut microbiota may help improve functional outcomes in adults at risk of sarcopenia. Objective: To evaluate whether a polyphenol-rich dietary recommendation associated with a nutritional supplement containing leucine, vitamin D3, and magnesium (SarcoDYN®), in the context of a standardized rehabilitation program, provides superior improvements in functional and patient-reported outcomes compared with rehabilitation alone. Methods: This quasi-experimental, non-randomized retrospective study included 28 adults at risk of sarcopenia, divided into a study group (rehabilitation + polyphenol-rich diet + SarcoDYN®) and a control group (rehabilitation only). Assessments were performed at baseline and after 3 months. Outcomes included SARC-F score, handgrip strength (dominant and non-dominant), sit-to-stand performance, perceived mobility, and perceived health status. Within- and between-group comparisons were conducted using appropriate parametric or non-parametric tests, and Spearman correlation analysis explored associations between functional, strength, and perceptual variables. Results: Both groups demonstrated significant within-group improvements in functional and patient-reported outcomes. At follow-up, the study group showed significantly better subjective outcomes, including lower SARC-F scores (U = 30.0, p = 0.002), higher perceived mobility (U = 40.0, p = 0.008), and higher perceived health status (U = 40.0, p = 0.008), compared with the control group. Objective post-intervention measures of handgrip strength and chair-rise performance did not differ significantly between groups. Correlation analysis revealed strong associations between SARC-F score, muscle strength, functional mobility, and perceived health. Conclusions: The combined intervention consisting of a polyphenol-rich diet that influence gut microbiota and SarcoDYN® supplementation, delivered alongside a structured rehabilitation program, was associated with better patient-reported mobility and health perception in adults at risk of sarcopenia. These findings should be considered exploratory and hypothesis-generating, and require confirmation in larger controlled studies.