in other countries (Cooper et al., 1992), and about habitual intakes of calcium and related nutrients according to specific cultural dietary practices, the implementation of the published DRIs should be used with caution outside the United States and Canada.
As defined in Chapter 1, the AI is used as a reference value when sufficient data are not available to estimate an average requirement. In this report, AIs rather than EARs and RDAs are developed for all nutrients for infants to age 1 year, and for calcium, vitamin D, and fluoride for all life stages. The method used to derive the AIs differs for infants and for each nutrient as follows.
The AI is the intake by healthy breast-fed infants as obtained from average human milk nutrient composition and average milk volume. Since infants self-regulate milk intake from the breast, it is presumed that larger infants, who may require more milk than the average population intake, will achieve this by increasing milk intake volume.
In this report, three major approaches were considered in deriving the AIs for calcium—calcium balance studies of subjects consuming variable amounts of calcium, a factorial model using calcium accretion based on bone mineral accretion data, and clinical trials which investigated the response of change in bone mineral content/density or fracture rate to varying calcium intakes. The prepublication version of this report estimated per cent maximal calcium retention derived from calcium balance data as one of the three major approaches considered to develop the recommended intakes for calcium. Subsequent comments received following the report's release in prepublication form indicated concerns with the statistical methodology used to obtain such estimates from the available balance data. In response to the technical issues raised, the DRI Committee determined for this final printed version that it would estimate desirable calcium retention in place of estimating the percent of maximal retention, using the same data and statistical methodology as was included in the prepublication version (see Appendix E).