another and from a predominantly Caucasian population to other ethnic groups.
Desirable rates of calcium retention, determined from balance studies, factorial estimates of requirements, and limited data on BMD and BMC changes, will be used as the primary indicators of adequacy. These indicators will be used as reasonable surrogate markers to reflect changes in skeletal calcium content.
The decision to set AIs for calcium rather than EARs was based on the following concerns: (1) uncertainties in the methods inherent in and the precise nutritional significance of values obtained from the balance studies that form the basis of the desirable retention model; (2) the lack of concordance between observational and experimental data (mean calcium intakes in the United States and Canada are much lower than are the experimentally derived values predicted to be required to achieve a desirable level of calcium retention); and (3) the lack of longitudinal data that could be used to verify the association of the experimentally derived calcium intakes for achieving a predetermined level of calcium retention with the rate and extent of long-term bone loss and its clinical sequelae, such as fracture. Taking all of these factors into consideration, it was determined that an EAR for calcium could not be established at the present time. The recommended AI represents an approximation of the calcium intake that, in the judgment of the DRI Committee, would appear to be sufficient to maintain calcium nutriture while recognizing that lower intakes may be adequate for some, but this evaluation will have to await additional studies on calcium balance over broad ranges of intakes and/or of long-term measures of calcium sufficiency.
There are no functional criteria for calcium status that reflect response to dietary intake in infants. Thus recommended intakes of calcium are based on an adequate intake (AI) that reflects the derived mean intake of infants fed principally with human milk.