Efficacy of vitamin D-3 as add-on therapy in patients with relapsing-remitting multiple sclerosis receiving subcutaneous interferon beta-1a: A Phase II, multicenter, double-blind, randomized, placebo-controlled trial

Joost Smolders*, Raymond Hupperts, Frederik Barkhof, Luigi M. E. Grimaldi, Trygve Holmoy, Joep Killestein, Peter Rieckmann, Myriam Schluep, Reinhold Vieth, Ulrike Hostalek, Lizette Ghazi-Visser, Manolo Beelke

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Recent studies have demonstrated the immunomodulatory properties of vitamin D, and vitamin D deficiency may be a risk factor for the development of MS. The risk of developing MS has, in fact, been associated with rising latitudes, past exposure to sun and serum vitamin D status. Serum 25-hydroxyvitamin D [25(OH)D] levels have also been associated with relapses and disability progression. The identification of risk factors, such as vitamin D deficiency, in MS may provide an opportunity to improve current treatment strategies, through combination therapy with established MS treatments. Accordingly, vitamin D may play a role in MS therapy. Small clinical studies of vitamin D supplementation in patients with MS have reported positive immunomodulatory effects, reduced relapse rates and a reduction in the number of gadolinium-enhancing lesions. However, large randomized clinical trials of vitamin D supplementation in patients with MS are lacking. SOLAR (Supplementation of VigantOL (R) oil versus placebo as Add-on in patients with relapsing-remitting multiple sclerosis receiving Rebif (R) treatment) is a 96-week, three-arm, multicenter, double-blind, randomized, placebo-controlled, Phase II trial (NCT01285401). SOLAR will evaluate the efficacy of vitamin D-3 as add-on therapy to subcutaneous interferon beta-1a in patients with RRMS. Recruitment began in February 2011 and is aimed to take place over 1 calendar year due to the potential influence of seasonal differences in 25(OH)D levels.
Original languageEnglish
Pages (from-to)44-49
JournalJournal of the Neurological Sciences
Issue number1-2
Publication statusPublished - 15 Dec 2011


  • Multiple sclerosis
  • Vitamin D
  • Interferon beta-1a
  • 25-Hydroxyvitamin D
  • 1,25-Dihydroxyvitamin D
  • Clinical trial
  • Biomarker

Cite this