Personalized antioxidant supplementation improves muscle strength, physical activity, and quality of life in patients with FSHD1: A real-world longitudinal study.

Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant myopathy characterized by progressive muscle weakness. Oxidative stress plays a central role in its pathogenesis. This longitudinal, real-world study evaluated the effect of personalized antioxidant supplementation on quadriceps muscle strength (maximum voluntary contraction; MVCQ), physical activity, and quality of life (QoL) in patients with FSHD1. Patients (aged 15-76) at Montpellier Hospital received tailored antioxidant supplementation (vitamins C and E, zinc, copper, and selenomethionine) based on blood analyses during annual visits: 107 completed one year and 74 continued for two more years of supplementation. Linear mixed model analyses showed a significant annual increase in the MVC of both dominant and non-dominant quadriceps muscles (+0.83 kg/year, +1.25 kg/year, respectively), improvement in physical activity, especially sports, and in QoL domains, notably physical role. Sex and age influenced outcomes: supplementation benefits were more pronounced in men and younger patients. Supplementation withdrawal resulted in the benefit loss, while attrition was unrelated to disease severity or treatment response. Overall, our findings suggest that personalized antioxidant supplementation may slow FSHD progression, improve muscle strength and quality of life. Baseline muscle strength and clinical scores, including the Brooke upper extremity scale score, allowed stratifying patients in responders and non-responders. These parameters underscore the importance of baseline assessments to predict outcomes and highlight the need of controlled studies to confirm these preliminary results.