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

10a

50a

Urinary losses

203b

162e

Endogenous fecal calcium

132b

156f

Sweat losses

63c

63c

Total

408

431

Absorption, percent

30d

30d

As adjusted for absorption

1,360

1,437

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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