Feasibility and acceptability of a 12-week probiotic intervention for people with Multiple Sclerosis: A mixed-methods single-arm trial

Objectives Increasing evidence suggests that the gut-brain axis plays a key role in the pathogenesis of Multiple Sclerosis (MS). MS is associated with an altered gut microbiome and increased intestinal permeability, potentially allowing pathogens to stimulate an immune response that affects the central nervous system. Microbiome-targeted therapies such as probiotics, have the potential to offer an alternative therapeutic approach to drug-based symptom management. Aim: To assess the feasibility, acceptability, safety and potential efficacy of a probiotic (Symprove™ UK) intervention for People with MS (PwMS). Methods Mixed-methods, single-arm feasibility trial, recruited through online MS groups and using remote data collection. Data were collected pre and post the 12-week probiotic intervention, with focus groups conducted after 12-weeks. Primary outcomes were recruitment, retention, adherence, acceptability and safety. Secondary outcomes included quality of life, MS symptoms, mental wellbeing, cognitive function, gut symptoms, functional ability and fatigue. Results Of 32 eligible participants, 29 were recruited (90.6%), with 98.8% adherence and 89.7% retention at 12-weeks. Participants primarily reported minor gastrointestinal side effects, which were expected and transient. One participant experienced severe diarrhoea, which was resolved within two weeks. Taking the probiotic was reported as acceptable, scoring highly in all seven acceptability domains; this was further reflected in the qualitative data. Quality of life and cognitive function scores were significantly improved (p = 0.007) after the 12-week probiotic intervention. Conclusions A 12-week probiotic intervention was feasible, safe and acceptable to PwMS. Improvements in health related outcomes suggest probiotics could play a role in symptom management. Further research is recommended to verify these findings. Trial registration Title How realistic and acceptable is a 12week probiotic trial for people with MS? Registration number NCT07304713, and registration date 24/12/25.