Scientific evidence indicates that calcium and vitamin D play key roles in bone health. The current evidence, however, does not support other benefits for vitamin D or calcium intake. More targeted research should continue. However, the committee emphasizes that, with few exceptions, all North Americans are receiving enough calcium and vitamin D. Higher levels have not been shown to confer greater benefits, and in fact, they have been linked to other health problems, challenging the concept that that “more is better.”The new vitamin D recommendations are bound to kick up some controversy because many researchers, led by Dr. Michael F. Holick, have argued that Americans should be consuming a lot more vitamin D than they are now, with 800 to 1,000 IU a day being the bare minimum and over 2,000 IU a day as being closer to the optimum.
Vitamin D proponents have also said the goal for blood levels should be 30 ng/mL. The IOM panel says levels that high are not associated with any health benefit and adds that levels above 50 ng/mL “may be reason for concern.”
The committee’s calcium recommendations are not likely to be nearly as controversial as its advice on vitamin D.
The summary of the panels’ report says national surveys show that most people in the United States and Canada get enough calcium, the notable exception being girls ages 9 to 18. The panel warns that postmenopausal women who take calcium supplements may be increasing their risk for kidney stones by getting too much of the mineral.