uncertainty of the values used for endogenous and sweat losses as well as efficiency of absorption.

AI Summary: Ages 31 through 50 Years

Based on available data from balance studies and BMD, the AI is placed at 1,000 mg (25 mmol)/day. Too few data for men are available to justify a separate AI for them.

AI for Men

31 through 50 years

1,000 mg (25 mmol)/day

AI for Women

31 through 50 years

1,000 mg (25 mmol)/day

Using the 1994 CSFII intake data, adjusted for day-to-day variation (Nusser et al., 1996), the median calcium intake for men, aged 31 through 50 years, is 857 mg (21.4 mmol)/day and their seventyfifth percentile of intake is 1,112 mg (27.8 mmol)/day (see Appendix D). Their AI of 1,000 mg (25 mmol)/day falls between the median and seventy-fifth percentile of calcium intake. Median calcium intake for women in this age range is 606 mg (15.2 mmol)/day; their ninetieth percentile of intake is 961 mg (24 mmol)/day and their ninety-fifth percentile is 1,082 mg (27.1 mmol)/day. Thus, their AI of 1,000 mg (25 mmol)/day falls between the ninetieth and ninety-fifth percentile of calcium intake based on the 1994 CSFII data.

Ages 51 through 70 Years
Indicators Used to Set the AI for Men

Calcium Retention. Desirable retention of calcium in men aged 51 through 70 years is zero which assumes that no net positive accretion of bone at this age in replete individuals serves a functional advantage. The relationship between calcium intake and calcium retention was determined from 181 balance studies conducted in ambulatory males of mean age 54 years (range 34 to 71 years) (Spencer et al., 1984). The subjects could not be divided into different age categories based on the data reported. Six different calcium intake levels ranging from 234 to 2,320 mg (5.8 to 58 mmol)/day were studied. The distribution of intakes in the 181 balance studies were: 111 balance studies in subjects with daily calcium intakes below 1,200 mg (30 mmol), 22 at approximately 1,200 mg, and 48 at intakes above 1,200 mg. The nonlinear regression equation derived from these data (Appendix E) was solved for a desirable reten-



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