Two new studies evaluating vitamin D in the support of a variety of medical issues were published in the most recent issue of the British Medical Journal (BMJ).
 
The first study, by lead author and cardiovascular epidemiologist Rajiv Chowdhury, conducted a systemic review and meta-analysis of observational studies and randomized-controlled trials, to determine if vitamin D was associated with mortality from cardiovascular, cancer or other health issues. Through the evaluation of 73 cohort studies with approximately 850,000 subjects, and 22 RCTs (vitamin D given alone versus placebo or no treatment; approx. 30,700 participants), researchers found an increased risk of death among those with low vitamin D levels. The observational studies showed an inverse association of circulating 25-hydroxyvitamin D concentration with risks of death from cardiovascular disease, death from cancer, and non-vascular, non-cancer death. Furthermore, supplementation with vitamin D3 reduced overall mortality significantly among older adults. However, the report concluded that further research was needed to establish the optimal dose and duration, and to determine if vitamin D3 or D2 have different effects on mortality risk.
 
An additional article in BMJ, from lead author Evropi Theodoratou, used an umbrella review of systematic reviews of observational studies, meta-analyses of observational studies, and meta-analyses of supplementation studies to assess “the breadth, validity, and presence of biases of the associations of vitamin D with diverse outcomes.” In the evaluation of these studies, the researchers found probable associations between vitamin D and birth weight, dental caries in children, maternal vitamin D concentrations at term, and parathyroid hormone concentrations in patients with chronic kidney disease requiring dialysis, however suggested further research was needed to better establish these connections.
 
The editorial in this issue of BMJ, by Paul Welsh, British Heart Foundation intermediate fellow, and Naveed Sattar, professor of metabolic medicine, discussed both studies, and were somewhat critical of vitamin D supplementation being considered a magic bullet for good health. The authors suggested that while further research is being conducted to determine the efficacy and optimal dosage of vitamin D, “clinicians should avoid costly measurement of 25-hydroxyvitamin D in asymptomatic patients outside of bone disease related conditions.”
 
The Council for Responsible Nutrition (CRN), Washington, D.C., both lauded the positive findings on vitamin D supplementation from the studies, as well as countered BMJ’s editorial.
 
Duffy MacKay, N.D., senior vice president, scientific and regulatory affairs, CRN, stated, “The body of scientific research demonstrating beneficial results for vitamin D has grown in recent years. We know that vitamin D is a critical conduit for multiple physiological bodily functions, as well as a tool for helping calcium absorption, which is essential to building strong bones. Now, a new systematic review and meta-analysis finds vitamin D supplementation may also play a significant role in reducing the risk of mortality, particularly in older adults. We agree with the study authors that further research should be done to identify an optimal dose and duration for this encouraging finding; but there is enough positive research currently to indicate that people should be supplementing with vitamin D for a variety of positive health outcomes.”
 
Commenting on the Theodoratou study, Dr. MacKay, questioned the “probable” associations concluded, and suggested, “There are very few things that provide clear cut scientific evidence when you’re talking about chronic disease, and if adding a simple vitamin D supplement might provide even probable benefits in this area—as one of a host of healthy habits—we should encourage that step.”
 
Dr. McKay also disagreed with the editorial’s conclusion that doctors should avoid testing for vitamin D levels until more research is presented. He said, “It is important for patients and their healthcare practitioners to work together to ensure they are getting the recommended amount of vitamin D—which is not easily obtainable through food alone, and may not be safely available through the sun, making vitamin D supplements a safe and beneficial alternative.”