No amount of vitamin D is able to compensate for inadequate total calcium intake; thus, setting a realistic DRI value for vitamin D requires that calcium is available in the diet in adequate amounts.
However, the committee has also commented on the consequences for one nutrient when the other is inadequate, in order to be transparent regarding the science underpinning the determination of reference values for these two nutrients.
The EARs, RDAs, and AIs for calcium are shown in Table 5-1 by life stage group. The studies used to estimate these values have been included in the review of potential indicators contained in Chapter 4. Therefore, in the discussions below, the relevant data are highlighted but not specifically critiqued again.
Data are not sufficient to establish an EAR for infants 0 to 6 and 7 to 12 months of age, and therefore AIs have been developed based on the available evidence. An AI value is not intended to signify an average requirement, but instead reflects an intake level based on approximations or estimates of nutrient intakes that are assumed to be adequate. Whether and how much the AI values for infants could be lowered and still meet the physiological needs for human milk-fed infants are unknown because mechanisms for adaptation to lower intakes of calcium are not well described for the infant population, and experimental data with overall relevance to estimating average requirements are extremely limited.
Calcium requirements for infants are presumed to be met by human milk (IOM, 1997). There are no functional criteria for calcium status that reflect response to calcium intake in infants (IOM, 1997). Rather, human milk is recognized as the optimal source of nourishment for infants (IOM, 1991; Gartner et al., 2005). There are no reports of any full-term, vitamin D–replete infants developing calcium deficiency when exclusively fed human milk (Mimouni et al., 1993; Abrams, 2006). Therefore, AIs for calcium