Background: Many studies have shown that active vitamin A derivatives suppress the formation of pathogenic T cells in multiple sclerosis (MS) patients. The aim of the present study is to determine the impact of vitamin A on disease progression in MS patients.

Methods: A total of 101 relapsing-remitting MS (RRMS) patients were enrolled in a 1-year placebo-controlled randomized clinical trial. The treated group received 25000 IU/d retinyl palmitate for six month followed by 10000 IU/d retinyl palmitate for another six month. The results of the expanded disability status scale (EDSS) and multiple sclerosis functional composite (MSFC) were recorded at the beginning and the end of the study. The relapse rate was recorded during the intervention. Patients underwent baseline and follow up brain MRIs.

Results: The results showed "Mean ± SD" of MSFC changes in the treated group was (-0.14 ± 0.20) and in the placebo group was (-0.31 ± 0.19). MSFC was improved significantly (P < 0.001) in the treatment group. There were no significant differences between the "Mean ± SD" of EDSS changes in the treated (0.07 ± 0.23) and placebo (0.08 ± 0.23) groups (P = 0.73). There were also no significant differences between the "Mean ± SD" of annualized relapse rate in the treated group (-0.36 ± 0.56) and placebo (-0.53 ± 0.55) groups (P = 0.20). The "Mean ± SD" of enhanced lesions in the treatment (0.4 ± 1.0) and in the placebo (0.2 ± 0.6) groups were not significantly different (P = 0.26). Volume of T2 hyperintense lesions "Mean ± SD" was not significantly different between treatment (45 ± 137) and placebo (23 ± 112) groups after intervention (P = 0.23).

Conclusion: Vitamin A improved total MSFC score in RRMS patients, but it did not change EDSS, relapse rate and brain active lesions.