10.15.10
Consumers should feel confident that the vitamin D intake levels needed to achieve the numerous health benefits demonstrated by growing scientific literature does not present a health risk, according to the Council for Responsible Nutrition (CRN), Washington, D.C.
Andrew Shao, PhD, senior vice president, Scientific and Regulatory Affairs, reached this conclusion based on a benefit-risk assessment published in the July issue of Osteoporosis International, of which he was a co-author along with his CRN colleague John Hathcock, PhD, senior vice president, Scientific and International Affairs, and academic researchers from Harvard University, Tufts University and the University of Zurich (Switzerland).
In recent years, research has pointed to benefits from vitamin D beyond bone health and at doses considerably higher than what is currently recommended by the Institute of Medicine (IOM). This 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 the 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 control trials (RCTs) that examined the effect of supplemental vitamin D on fall and fracture risk. The researchers found that optimal benefits were observed at a mean serum 25(OH)D level—the body’s marker of vitamin D nutritional status—between 75 and 110 nmol/l (30-44 ng/ml), resulting from a vitamin D dose of about 1000 IU per day. 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 concluding that up to 10,000 IU/day can be consumed without risk for adverse effects.
“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. This combined benefit-risk analysis allows for the comparison of the efficacy and safety of vitamin D in a side-by-side manner,” according to Dr. Shao. “It is clear from our present and past analyses that optimal blood levels of vitamin D achieved with oral doses of up to 4000 IU daily are associated with little, if any, risk.”
With the IOM currently reviewing the scientific literature to revise the Dietary Reference Intakes (DRIs) for vitamin D to more closely match the updated science, this type of published analysis should be useful.
“The IOM recommendations will be released soon and we trust they will take this latest analysis into consideration,” said Dr. Shao. “We’re 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.”
