Self-reported use of vitamin D supplements is associated with higher physical quality of life scores in multiple sclerosis.

Background: Sun exposure and vitamin D, including intake and serum levels, have been associated with reduced risk of MS onset and less progression and may affect quality of life (QoL). We investigated the prospective relationship of these factors with QoL from baseline to 2.5 years' follow-up, in an international cohort of people with MS.

Methods: Data derive from the HOLISM international cohort. Sun exposure and vitamin D supplement use were queried at both timepoints. QoL was assessed by MSQOL-54, estimating physical and mental health QoL composite scores. Characteristics of QoL were assessed by linear regression, adjusted for age, sex, socioeconomic status, treated comorbidity number, MS type, disability, clinically significant fatigue, prescription antidepressant medication use, and ongoing relapse symptoms, and baseline QoL score, as appropriate, estimating adjusted coefficients (aβ).

Results: At 2.5-year review, QoL scores were higher among those reporting taking vitamin D supplements (physical: aβ=3.58, 95%CI=1.35-5.80; mental: aβ=3.08, 95%CI=0.72-5.44), particularly average daily dose over 5,000IU/d. Baseline-reported vitamin D supplementation was associated with greater increase in physical (aβ=1.02, 95%CI=0.22-1.81), but not mental QoL (aβ=0.11, 95%CI=-1.00-1.23). Sun exposure was cross-sectionally associated with higher QoL scores at follow-up but was not associated with change in QoL.

Conclusions: Self-reported vitamin D supplement use was cross-sectionally associated with higher physical and mental QoL, but prospectively only with increased physical QoL.