Dietary adherence and disability evolution in multiple sclerosis: An exploratory 12-month prospective cohort study

Lifestyle factors may influence disability trajectories in multiple sclerosis (MS), yet prospective data linking sustained dietary adherence to objective clinical outcomes remain limited. Homocysteine, a metabolite involved in one-carbon metabolism, represents a biologically plausible mediator between nutrition and neurodegeneration, although its longitudinal clinical relevance in MS is uncertain. This study aimed to investigate whether adherence to a structured dietary intervention is associated with longitudinal changes in plasma homocysteine levels and disability progression in patients with MS over 12 months.

In this prospective cohort study, 41 patients with MS were followed for 12 months. Dietary adherence was quantified using a structured follow-up scale (range 2-6). Plasma homocysteine levels and Expanded Disability Status Scale (EDSS) scores were assessed at baseline, 6 months, and 12 months. Associations between adherence, metabolic changes, and EDSS evolution were evaluated using correlation analyses and multivariate linear regression adjusting for age, sex, BMI, baseline EDSS, and treatment line.

Baseline mean homocysteine was 10.91 ± 6.94 μmol/L and decreased to 8.24 ± 3.33 μmol/L at 6 months, remaining stable at 8.27 ± 2.42 μmol/L at 12 months. Between-group differences in homocysteine showed a trend toward significance at 12 months (ANOVA p = 0.059). Mean EDSS increased slightly from 1.14 to 1.23 in the overall cohort (p > 0.05). However, EDSS evolution differed according to dietary adherence (ANOVA p = 0.009): low-adherence patients showed a mean EDSS increase (+0.53 ± 0.72), whereas high-adherence patients showed a mean EDSS decrease (-0.56 ± 1.08). Given the low baseline EDSS, short follow-up, and small high-adherence subgroup, these changes should be interpreted as exploratory differences in short-term EDSS trajectory rather than confirmed clinical improvement and do not establish causality. Adherence score was inversely correlated with EDSS change (r = -0.57, p = 0.0006) and remained independently associated in multivariate analysis (β = -0.45, 95% CI -0.68 to -0.22, p = 0.0005).

Higher adherence to the dietary counselling programme was associated with a more favourable short-term disability trajectory over 12 months. However, causality cannot be inferred, and the clinical significance of these modest changes remains uncertain. Because the adherence score was not formally validated and may partly reflect broader health-related behaviours or engagement with care, and because the dietary intervention was individualized, the study cannot identify specific dietary components or dietary patterns associated with disability trajectories. These exploratory findings require confirmation in larger controlled studies using validated dietary assessment instruments.