The effect of vitamin D supplementation on pain: an analysis of data from the D-Health randomised controlled trial
Aninda Rahman, Mary Waterhouse, Catherine Baxter, Briony Duarte Romero, Donald S.A. McLeod, Bruce K. Armstrong, Peter R. Ebeling, Dallas R. English, Günter Härtel, Michael G. Kimlin, Rachel O’Connell, Jolieke C. van der Pols, Alison Venn, Penelope M. Webb, David C. Whiteman, Rachel Ε. Neale
Abstract
Abstract Observational studies suggest that 25-hydroxy vitamin D (25(OH)D) concentration is inversely associated with pain. However, findings from intervention trials are inconsistent. We assessed the effect of vitamin D supplementation on pain using data from a large, double-blind, population-based, placebo-controlled trial (the D-Health Trial). 21 315 participants (aged 60–84 years) were randomly assigned to a monthly dose of 60 000 IU vitamin D 3 or matching placebo. Pain was measured using the six-item Pain Impact Questionnaire (PIQ-6), administered 1, 2 and 5 years after enrolment. We used regression models (linear for continuous PIQ-6 score and log-binomial for binary categorisations of the score, namely ‘some or more pain impact’ and ‘presence of any bodily pain’) to estimate the effect of vitamin D on pain. We included 20 423 participants who completed ≥1 PIQ-6. In blood samples collected from 3943 randomly selected participants (∼800 per year), the mean ( sd ) 25(OH)D concentrations were 77 ( sd 25) and 115 ( sd 30) nmol/l in the placebo and vitamin D groups, respectively. Most (76 %) participants were predicted to have 25(OH)D concentration >50 nmol/l at baseline. The mean PIQ-6 was similar in all surveys (∼50·4). The adjusted mean difference in PIQ-6 score (vitamin D cf placebo) was 0·02 (95 % CI (−0·20, 0·25)). The proportion of participants with some or more pain impact and with the presence of bodily pain was also similar between groups (both prevalence ratios 1·01, 95 % CI (0·99, 1·03)). In conclusion, supplementation with 60 000 IU of vitamin D 3 /month had negligible effect on bodily pain.