Vitamin D: Study Finds Little Justification For Prescribing For Most Disease Prevention Interview with:
Professor Mark Bolland
Senior Research Fellow in the Department of Medicine
University of Auckland, New Zealand What are the main findings of the study?

Prof. Bolland: We pooled data from randomised controlled trials of vitamin D supplements in traditional meta-analyses and trial sequential analyses to assess the effect on important health outcomes. We found that vitamin D supplements (with or without calcium) had no effect on myocardial infarction, stroke, total cancer, or total fracture, and further similar trials are unlikely to alter these conclusions. For hip fracture, the results were more complicated. There was uncertainty as to whether vitamin D by itself increased the risk of hip fracture or had no effect, whereas the combination of vitamin D with calcium had no effect on hip fracture in people living in the community, but reduced hip fracture risk in two trials of elderly women living in residential care. Were any of the findings unexpected?

Prof. Bolland: There are widely diverging views on the effectiveness of vitamin D supplements. The findings will probably come as no surprise to people who have held sceptical views about the effectiveness of vitamin D supplementation. On the other hand, people who have endorsed calls for widespread vitamin D supplementation will probably view these results as surprising. What should clinicians and patients take away from your report?

Prof. Bolland: There is little justification currently for prescribing vitamin D to prevent heart attack, stroke, cancer, or fractures in otherwise healthy people living in the community. For people at risk of osteomalacia because of very low vitamin D levels (frail elderly people living in residential care, people who actively avoid the sun, and people with deeply pigmented skin), it is worth considering taking vitamin D supplements on an individual basis. For other people, vitamin D supplements are unnecessary. What recommendations do you have for future research as a result of this study?

Prof. Bolland: Doing more trials that are similar to existing one are difficult to justify, so future trials will have to have a strong evidence base as to why their results are likely to differ from existing trials. Research should focus on better defining what vitamin D level is adequate for health.


The effect of vitamin D supplementation on skeletal, vascular, or cancer outcomes: a trial sequential meta-analysis
Mark J Bolland, Andrew Grey, Greg D Gamble, Ian R Reid online January 24, 2014