In May 2019 researchers from New Zealand published the results of their study to assess the effectiveness of monthly vitamin D supplementation in reducing the incidence of a range of acute and chronic diseases. A total of 5,110 adults, aged 50-84 years, were followed-up for an average of 3 years. Each individual was given either vitamin D supplementation or placebo. In the first month, those individuals receiving vitamin D supplementation received 200,000 IU and thereafter, each month, 100,000 IU. Outcomes were monitored through routinely collected health data and self-completed questionnaires. Results showed no beneficial effect of vitamin D supplementation on the incidence of cardiovascular disease, falls, non-vertebral fractures and all cancer. However, beneficial effects from vitamin D supplementation were seen in that it encouraged those individuals on long term statin therapy to take their medication, to increase bone mineral density and improve arterial function in individuals with low vitamin D levels. Vitamin D supplementation was also seen to improve lung function in those who had smoked at one time or another, especially if they had vitamin D deficiency. Therefore, 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.
Scragg RKR. Overview of results from the Vitamin D Assessment (ViDA) study. J Endocrinol Invest. 2019 May 23. [Epub ahead of print]