VIDA Findings Do Not Support Use of Vitamin D Supplements as Cancer Preventative

Monthly, long-term high-dose vitamin D supplementation without calcium may not be associated with a reduced risk of cancer, according to a study published in JAMA Oncology.

A previous hypothesis stated that low levels of vitamin D may be a risk factor for several types of cancer, but evidence from randomized clinical studies assessing vitamin D supplementation have been conflicting.

For this post-hoc analysis of the Vitamin D Assessment (VIDA) study, researchers assessed the incidence of all primary invasive and in situ malignant neoplasms of 5108 patients randomly assigned to oral vitamin D₃ or placebo. Patients received an initial bolus dose of vitamin D₃ 200,000 IU, then monthly doses of 100,000 IU thereafter for a median of 3.3 years. Deseasonalized mean vitamin D concentration was 26.5 (9.0) ng/mL, and the median age was 65.9 years.

Overall, there were 328 total cases of cancer; 6.5% (165) and 6.4% (163) of patients in the vitamin D and placebo groups, respectively, reported a primary outcome of cancer (P =.95). No significant differences were observed between the risk of cancer between men and women, or when assessed for higher (20 ng/mL or higher) or lower vitamin D levels.

The authors concluded that “we showed that monthly high-dose vitamin D supplementation without calcium for up to 4 years is not associated with cancer prevention. Further research is required to study the influence of daily or weekly doses of vitamin D on the risk of cancer for longer periods of time.”

Reference

Scragg R, Khaw KT, Loop L, et al. Monthly high-dose vitamin D supplementation and cancer risk [published online July 19, 2018]. JAMA Oncol. doi: 10.1001/jamaoncol.2018.2178