mated as 140 mg/day for formula-fed infants (personal communication, Dr. Steven Abrams, February 22, 2010).
For the purpose of developing an AI for this age group, it is assumed that infants who are fed human milk have intakes of solid food similar to those of formula-fed infants of the same age (Specker et al., 1997). Based on data from Dewey et al. (1984), mean human milk intake during the second 6 months of life would be 600 mL/day. Thus, calcium intake from human milk with a calcium concentration of about 200 mg/L during this age span (Atkinson et al., 1995) would be approximately 120 mg/day. Adding the estimated intake from food (140 mg/day) to the estimated intake from human milk (120 mg/day) gives a total intake of 260 mg/day. Again, this AI is slightly and probably insignificantly less than the 1997 AI (IOM, 1997) but is the current best estimate.
For these life stage groups, the focus is the level of calcium intake consistent with bone accretion and positive calcium balance. Studies conducted primarily between 1999 and 2009 (see Table 5-2) provide a basis for estimating EARs and calculating RDAs. In contrast to earlier reference value deliberations for which there were virtually no available studies focused on children and adolescents, this committee benefited from several recent studies that used children as subjects.
The approach used for children was to determine average calcium accretion through bone measures such as DXA and average calcium retention as estimated by calcium balance studies (i.e., positive balance). Next, the factorial method (IOM, 1997) was used with these two data sets to estimate the intake needed to achieve the bone accretion. Average bone calcium accretion is used rather than peak calcium accretion because the committee judged this value to be more consistent with meeting the needs