Supplemental Vitamin D Safe, Efficacious

WASHINGTONConsumers looking to consume more vitamin D to achieve numerous health benefits demonstrated by many recent studies can do so without concern of health risks, according to Andrew Shao, Ph.D., senior vice president of scientific and regulatory affairs, Council for Responsible Nutrition (CRN). Shao and CRNs senior vice president of scientific and international affairs, John Hathcock, Ph.D., co-authored a risk-benefit analysis on vitamin D intake, with colleagues from Harvard University, Tufts University and the University of Zurich (Osteoporos Int. 2010 Jul; 21(7):1121-32. DOI: 10.1007/s00198-009-1119-3).

The analysis compared the benefits of supplemental vitamin D as measured by the incidence of falls, fractures, cardiovascular outcomes and colon cancer with the potential risk of adverse effects as measured by elevated blood calcium. The authors concluded vitamin D intake needed for optimal benefit is far from that which poses a risk.

To assess benefit, the authors based their analysis on published double blind, randomized controlled trials (RCTs) examining the effect of supplemental vitamin D on fall and fracture risk. They found optimal benefits were observed at a mean serum 25(OH)D levelthe bodys marker of vitamin D nutritional statusbetween 75 and 110 nmol/l (30-44 ng/ml), resulting from a vitamin D dose of about 1,000 IU/d. The authors also assessed published cohort data on cardiovascular outcomes and colorectal cancer risk, and found optimal benefit at similar serum 25(OH)D levels. To assess risk, the authors examined data from these same studies as well as additional trials involving supplementation with high doses of vitamin D. At these optimal and even much higher levels, the authors observed no increase in risk for elevated blood calcium, consistent with findings from a previous analysis by Shao and Hathcock, which concluded up to 10,000 IU/d can be consumed without risk for adverse effects (Am J Clin Nutr. 2007;85:6-18).

Over the years, a large body of research has accrued on both the benefits and potential risks of vitamin D, but these analyses on efficacy and safety have been conducted separately," Shao said. This combined benefit-risk analysis allows for the comparison of the efficacy and safety of vitamin D in a side-by-side manner. It is clear from our present and past analyses that optimal blood levels of vitamin D achieved with oral doses of up to 4,000 IU/d are associated with little, if any, risk."

With the Institute of Medicine (IOM) currently reviewing the scientific literature to revise the Dietary Reference Intakes (DRIs) for vitamin D to more closely match the updated science, Shao expects this type of published analysis will be useful. The IOM recommendations will be released soon and we trust they will take this latest analysis into consideration," he said. Were so much farther along scientifically than where we were when the current DRIs were published more than 13 years ago. We now know much more about the benefits of vitamin D, and we know there is a wide safety margin between the dose that is beneficial and where risk for adverse effects begins in normal healthy adults. The next step is to get more useful recommendations to the general public."