What Do We Tell Our Patients about Calcium and Vitamin D Supplementation

In the current era of rapid dissemination of medical information, it is paradoxically difficult sometimes for patients to make the appropriate choices regarding their health. As part of their training and culture, physicians generally examine the results of a given study in the context of an overall body of evidence. By contrast, patients are often perplexed by the results of a given, possibly wellpublicized study (or set of studies) that may be at odds with the advice their own physician has provided them. Potential outcomes of this include a change in behavior or medications by the patient or, hopefully, an extended discussion with their physician regarding the appropriate course of action. A case in point is the previously simple issue of calcium and vitamin D supplementation as part of an overall regimen for the prevention or treatment of osteoporosis. This was highlighted to me by a recent patient with osteoporosis who returned for a follow-up visit. Per my usual practice, I had asked her to take approximately 800 IU of vitamin D and 1200 mg of calcium and she had followed this advice for many years. On this occasion, however, as I went through her list of medications, I discovered that through various supplements, she was consuming approximately 6000 IU of vitamin D and had discontinued all calcium supplements. When I pressed her for her reasons for these changes, she replied that all of her reading indicated that “vitamin D was good for you and prevented fractures, cancer, and heart disease, whereas calcium supplements caused heart attacks.” As I considered how best to respond (my initial reaction was a sense of exasperation), I came to realize that from her perspective, she was just trying to be an educated, responsible patient. Other than the fact that she should have checked with me before changing her regimen, she was simply reacting to information she (and other patients like her) are being flooded with regarding osteoporosis and a host of other medical issues. It is in this context that the 2010 Institute of Medicine (IOM) report on dietary reference intakes for vitamin D and calcium is of particular importance (1). The key findings of this report are nicely summarized by the members of the IOM Committee in this issue of JCEM (2) and serve to bring clarity, for physicians and patients, on the overall body of evidence on which to base recommendations for vitamin D and calcium supplements. As reflected by the decisions made by the patient described above, there has been considerable interest and publicity on the potential benefits of vitamin D supplementation in not only preventing fractures, but also reducing the risk of cardiovascular disease, diabetes mellitus, cancer, and immune dysfunction (3). To rigorously evaluate the evidence for each of these outcomes, the IOM Committee used two key systematic reviews conducted by the Agency for Healthcare Research (AHRQ) in 2007 (4) and 2009 (5), and also conducted its own literature review. A variety of specific skeletal and nonskeletal “indicators” on which to base the current recommendations were used. As summarized by Ross et al. (2), the IOM Committee concluded that bone health was the only outcome for which the available evidence was sufficient to support the development of a dietary reference intake (DRI) for calcium and vitamin D. The development of the DRI also includes specification of the estimated average requirement (EAR; corresponding to the median intake of the population), the recommended dietary allowance (RDA;