Vitamin D supplementation and disease modification

Margitta et al. Effect of vitamin D3 supplementation on relapses, disease progression and measures of function in persons with multiple sclerosis: exploratory outcomes from a double-blind randomised controlled trialMult Scler 1352458511434607, first published on February 21, 2012 as doi:10.1177/1352458511434607

Background: High vitamin D levels may reduce the risk of relapses and disease progression in MS.

Methods: This 96-week randomised controlled trial was designed to assess the effect of vitamin D3 supplementation on bone mineral density in persons with MS. Supplementation with 20,000 IU vitamin D3 weekly raised median serum 25-hydroxy vitamin D (25[OH]D) to 121 nmol/L.

"Some in the field believe that levels >100 nmol/L are normal physiological levels; this is based on blood levels in indigenous populations from Africa with a traditional outdoor lifestyle."

The modified intention to treat analysis included 35 persons in the vitamin D3 group and 33 in the placebo group. Participants were age 21 to 50 years and fully ambulatory (median EDSS 2.5). They studied the effect of supplementing vitamin D3 on the exploratory outcomes annualised relapse rate (ARR), EDSS, multiple sclerosis functional composite (MSFC) components, grip strength, and fatigue.

Results: After 96 weeks, there was no significant difference between groups in ARR (absolute difference 0.10, 95% CI -0.07 to 0.27; p = 0.25), EDSS (absolute difference -0.01, 95% CI -0.35 to 0.35; p = 0.97), MSFC components, grip strength, or fatigue.

Conclusion: Supplementation with 20,000 IU vitamin D3 weekly did not result in beneficial effects on the measured MS-related outcomes. This study was not powered to address clinical outcomes, but none of the results were suggestive of an effect in this unselected population of fully ambulatory persons with multiple sclerosis.

Quote: 'This study was not powered to address clinical outcomes.'

"Why then did they report clinical outcomes?"
"Bad science; this study is simply too small to make any claims of a disease-modifying effect. It should report on what it was meant to report on bone mineral density. Reporting this data may be counter-productive and give the impression that vD supplementation has no disease-modifying effects. What we need is properly powered studies!"