TABLE 4-4 Factorial Approach for Determining Calcium Requirements in Adults Aged 19 through 30 Years


Females (mg/day)

Males (mg/day)

Peak calcium accretion



Urinary losses



Endogenous fecal calcium



Sweat losses






Absorption, percent



As adjusted for absorption



a Taken from calculations by Peacock (1991) based on metacarpal morphometry data of Garn (1972).

b Wastney et al. (1996).

c Charles et al. (1983).

d Heaney et al. (1988).

e Matkovic (1991).

f Heaney and Skillman (1964).

achieved was 1,026 mg (25.6 mmol)/day for females and 1,236 mg (30.9 mmol)/day for males (Figure E-2).

Using the same database with data from men and women combined to determine the plateau intake using the two-component split, linear-regression model of Matkovic and Heaney (1992), the plateau retention of calcium was reached at an intake of 957 mg (23.9 mmol)/day.

Factorial Approach. The factorial approach for estimating calcium requirements for young adults is given in Table 4-4. This approach gives higher daily estimates of requirements (1,360 mg [34 mmol] for females and 1,437 mg [35.9 mmol] for males) than the desirable calcium retention approach (see above). The differences in derived values for calcium intake may be a result of the correction for endogenous fecal calcium applied in the factorial method which is based on only one recent study (Wastney et al., 1996) and/or the fact that a 30 percent absorption factor was applied. For the latter, the absorption value is taken from a derivative report which included multiple study designs on 16 women and 6 men (Heaney et al., 1988), and thus represents the average of all the subjects. Given the variety of study designs, it isn't possible to apply the gender-specific data.

AI Summary: Ages 19 through 30 Years

For this age group, estimates of average calcium requirements

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