Overview of results from the Vitamin D Assessment (ViDA) study.

Abstract

The Vitamin D Assessment (ViDA) study is a randomised, double-blind, placebo-controlled trial to evaluate the efficacy of monthly vitamin D supplementation in reducing the incidence of a range of acute and chronic diseases and intermediate outcomes. The study was carried out in Auckland, New Zealand, among 5110 adults, aged 50-84years, who were followed for a median 3.3years. The intervention was vitamin D3 (2.5mg or 100,000IU) or placebo softgel oral capsules, mailed monthly to participants' homes, with two capsules sent in the first mail-out post-randomisation (i.e. 200,000IU bolus, or placebo), followed 1month later (and thereafter monthly) with 100,000IU vitamin D3 or placebo capsules. Outcomes were monitored through routinely collected health data and self-completed questionnaires. The results showed no beneficial effect of vitamin D supplementation on incidence of cardiovascular disease, falls, non-vertebral fractures and all cancer. However, beneficial effects from vitamin D supplementation were seen: for persistence with taking statins in participants on long-term statin therapy; and also in bone mineral density and arterial function in participants with low 25-hydroxyvitamin D levels, and in lung function among ever smokers (especially if vitamin D deficient). The latter findings are consistent with several previous studies, CONCLUSION: Monthly high-dose vitamin D supplementation does not prevent a range of diseases, but may be beneficial for some intermediate outcomes in people who are vitamin D deficient. Australian New Zealand Clinical Trials Registry identifier: ACTRN12611000402943.