IntroductionMultiple Sclerosis (MS) is a chronic autoimmune disorder causing nerve sheath demyelination and symptoms such as muscle weakness, mobility decline, and lack of coordination 1,2, generating unique health challenges and an economic burden 3-5. Patients experience reductions in bone and skeletal muscle mass6, muscle strength and function 7,8, and increased fracture risk 9, negatively impacting quality of life 10. Lower limb strength impairments8, poor balance 11 and spasticity12 also contribute to a lower quality of life10. Pharmacological treatments have been the primary option for patients with MS 13.Recent research has explored non-pharmacological treatments such as exercise, nutritional supplementation, and improved sleep quality14-21. Resistance exercise (RE) is particularly beneficial for MS rehabilitation, as it improves muscle strength and function, mobility, quality of life 22,23, and the immune system 24. High-dose vitamin D supplementation raises interleukin-10 (IL-10) levels in MS patients19, who tend to have lower levels of IL-10, which may contribute to the disease’s development 25. However, RE and vitamin D may not always improve physical fitness20,21. This could be due to unsatisfactory energy and protein intake, containing essential amino acids (EAA), which are necessary to stimulate muscle protein synthesis (MPS) and ultimately address sarcopenia 26, a condition prevalent in MS patients 27. EAA-based supplements enriched with L-leucine increase protein intake and optimise MPS in healthy older adults without compromising total energy intake during mealtimes28,29 and plasma EAA concentration is associated with muscle function in older women in the community 30. A higher protein intake, including specific amino acids, may positively impact bone health through mechanisms such as increasing insulin-like growth factor 1 (IGF-1) 31,32. Therefore, addressing dietary protein deficiencies alongside RE may optimise musculoskeletal health and function in female MS patients. This case study evaluated the effects of a 24-week home-based intervention, including EAAs and vitamin D3 supplementation, on muscle, bone, muscle strength, and function in a female patient with MS.