Fish Consumption Leads to Better Disability Progression in Multiple Sclerosis

Anna Hedström, MD, PhD

A recently published population-based case-control study revealed that higher fish consumption was associated with more favorable disability progression in patients with multiple sclerosis (MS), further supporting diet as a modifiable factor. While these findings need validation, patients who ate more fish demonstrated reduced risk of confirmed disability worsening (CDW) and progression to worse Expanded Disability Status Scale (EDSS) scores.¹

Between April 2005 and June 2015, the EIMS recruited 2880 newly diagnosed patients with MS from hospital-based neurology units and privately run clinics across Sweden. Of the 2880 patients, 2767 (96%) were followed-up with EDSS scores in the Swedish MS registry. After exclusion of those with incomplete information regarding fish consumption habits (n = 48), the study’s final analysis comprised 2719 patients with MS.

Led by senior author Anna Hedström, MD, PhD, a senior research specialist at Karolinska Institute, participants were asked to complete a digital follow-up questionnaire in 2021, capturing lifestyle habits from the time of diagnosis. Of the 1821 patients who completed the questionnaire, 1719 were followed up with EDSS in the Swedish MS registry. Among the entire cohort, the mean age at diagnosis of MS and inclusion in EIMS was 38 (SD, 11) years.

When analyzing lean and oil fish separately, results revealed that weekly intake of these foods was associated with a reduced risk of CDW compared with those who seldom consumed fish (lean fish: HR, 0.84 [95% CI, 0.71-1.00]; oily fish: HR, 0.81 [95% CI, 0.68-0.97]). Due to a moderate correlation between lean and oily fish intake (r = 0.4, P < 0.0001), separate analysis wasn’t feasible; however, participants with higher consumption of both had the greatest reduction in CDW risk.

A fish intake frequency score, ranging from 2-6, was developed to assess the overall intake of lean and oily fish. Through this, results revealed that those in the highest fish consumption bracket had greater reduced risk of CDW (adjusted HR, 0.66; 95% CI, 0.51-0.86), as well as a lower risk of reaching EDSS 3 (adjusted HR, 0.55; 95% CI, 0.53-0.79), and EDSS 4 (adjusted HR, 0.57; 95% CI, 0.33-0.96) compared with the reference group.

"Fish is a rich source of several nutrients that might benefit individuals with MS, namely, omega-3 fatty acids and taurine," the study authors wrote.¹ "Omega-3 fatty acids are well-known for their anti-inflammatory properties and have been associated with reduce inflammation associated with MS. While omega-3 fatty acids, predominantly found in oily fish, may contribute to reduced disability progression, the beneficial effects observed from lean fish consumption suggest that other factors may also play a significant role."

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Among those who completed the follow-up questionnaire in 2021 (n = 1719), 24% (n = 412) had altered their fish consumption frequency (288 increased and 124 decreased). All told, participants who increased fish consumption from a score of 2–3 to 5–6 within 5 years post-diagnosis (n = 133) had a significantly lower risk of CDW (HR, 0.80, 95% CI, 0.63–0.99) compared to those with consistently low intake (n = 400). Notably, among the 16 individuals who increased from a score of 2 to 5–6, the risk was even lower (HR, 0.41; 95%, CI 0.17–0.95) versus those who remained at the lowest level (n = 101).

The association between high fish consumption and reduced CDW risk remained consistent after adjusting for lifestyle factors, vitamin D, and sampling month. Stratified by body mass index (BMI), the HR was 0.71 (95% CI, 0.51–0.98) for BMI of 25 or less and 0.64 (95% CI 0.43–0.94) for BMI greater than 25. Among those recruited between 2007–2011, the association held (HR, 0.67; 95% CI 0.46–0.97), with a continued trend of decreasing CDW risk as fish intake increased (HR, 0.93; 95% CI 0.87–1.00).

This study has several limitations, including the potential for recall bias in self-reported fish consumption and the lack of data on preparation methods, which could affect nutritional content. While adjustments were made for many clinical and lifestyle variables, their limited impact on the results suggests possible residual confounding. To avoid over-adjustment, only key covariates were included in the final model, though a fully adjusted analysis was provided. Still, unmeasured or misclassified factors may have influenced the findings.

REFERENCE
1. Johansson E, Guo J, Wu J, Olsson T, Alfredsson L, Hedström AK. Impact of fish consumption on disability progression in multiple sclerosis. Neurol, Neurosurg, & Psych. Published online February 25, 2025. doi:10.1136/jnnp-2024-335200