Vitamin A and systemic inflammation as protective factors in multiple sclerosis

Background: Vitamin A is important for the immune system, and might suppress inflammatory activity in multiple sclerosis (MS). Objectives: We aimed to examine if vitamin A levels were associated with MS risk in samples collected prospectively and during gestation. Methods: We measured Retinol Binding Protein (RBP - a surrogate marker for vitamin A) and high-sensitivity C-reactive protein (hs-CRP) levels, in (1) prospectively collected biobank blood samples from MS cases and controls, and (2) gestational samples where the offspring had later developed MS, and gestational control samples. The risk of MS was calculated using matched multivariable logistic regression adjusted for confounders. Results: In prospective samples, RBP levels within the second quintile (vs. the first) were associated with a lower MS risk (OR = 0.38, 95% CI 0.19-0.74). No effect on MS risk in the offspring by gestational RBP levels was found. In young subjects hs-CRP levels 10 mg/l in prospective samples were associated with a lower MS risk (OR = 0.36, 95% CI 0.14-0.95). Conclusions: Our results suggest that sub-optimal vitamin A levels may be associated with MS risk. The association between hs-CRP levels and MS risk in young subjects may support the role of the hygiene hypothesis in MS aetiology.