Abstract
BACKGROUND: Emerging evidence indicates that diet, including fish consumption, may play a role in the development and progression of multiple sclerosis (MS). We aimed to investigate the influence of fish consumption on disability progression in MS. METHODS: Incident cases from the population-based case-control study Epidemiological Investigation of MS (n=2719), with data on fish intake and Expanded Disability Status Scale (EDSS) outcomes, were categorised by fish consumption and followed up to 15 years post-diagnosis through the Swedish MS registry. A digital follow-up questionnaire in 2021 assessed changes in fish intake over time (n=1719). Cox regression models, adjusted for clinical and demographic variables, were used to evaluate 24-week confirmed disability worsening (CDW), and progression to EDSS 3 and EDSS 4. RESULTS: Higher total consumption of lean and oily fish at diagnosis was associated with a reduced risk of CDW (HR 0.66, 95% CI 0.51 to 0.86), EDSS 3 (HR 0.55, 95% CI 0.39 to 0.79) and EDSS 4 (HR 0.57, 95% CI 0.33 to 0.96) compared with low consumption. These associations showed significant trends and remained consistent after further adjustment for various lifestyle factors. The protective effects were more pronounced among patients who maintained consistent fish consumption during the follow-up period. CONCLUSIONS: Our findings suggest that higher fish consumption is associated with more favourable MS disability progression, supporting diet as a potentially modifiable factor. Replication and validation are needed before transfer to practice.