Vitamin A is not associated with exacerbations in multiple sclerosis

Background: Vitamin A is a multifunctional vitamin that can inhibit the formation of Th17 cells, which are probably involved in the development of relapses in MS. Furthermore, it promotes Treg formation. Therefore, vitamin A can be hypothesized to be lower in patients than in healthy controls, and to decrease relapse risk in relapsing-remitting MS (RRMS) patients. Objective: To compare vitamin A levels in MS patients and controls, and to investigate whether vitamin A levels are associated with relapse risk. Methods: In a case-control study all-trans-retinol levels were compared between 31 RRMS patients and 29 matched controls. In a prospective longitudinal study in 73 RRMS patients, serum samples for all-trans-retinol measurements were taken every eight weeks. Associations between all-trans-retinol concentrations and relapse rates were calculated using Poisson regression with the individual serum levels as time-dependent variable. Associations between vitamin A and vitamin D were calculated. Results: Mean vitamin A levels were lower in patients (2.16 mu mol/ l) than in controls (2.44 mu mol/l) but with borderline significance (p=0.05). In the longitudinal study, during follow-up (mean 1.7 years), 58 patients experienced a total of 139 relapses. Monthly moving averages of all-trans retinol levels were categorized into tertiles: a low (<2.9 mu mol/l), medium (2.9-3.7 mu mol/l) and high level (>3.7 mu mol/l). Relapse rates were not associated with serum all-trans retinol levels (p> 0.2), in univariate nor in multivariate analysis. Serum concentrations of all-trans-retinol and 25-OH-vitamin D were positively correlated, although this correlation was weak (r=0.15). Conclusion: We did not find evidence for a role for vitamin A in the disease course of RRMS. We did find an association between vitamin A and D levels in the RRMS patients, possibly explained by dietary products that contain both fat-soluble vitamins. (C) 2013 The Authors. Published by Elsevier B.V. Open access under CC BY-NC-ND license