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DRI DIETARY REFERENCE INTAKES FOR Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride
(Nusser et al., 1996), the median calcium intake for boys aged 9 through 13 is 980 mg (24.5 mmol)/day, the seventy-fifth percentile of intake is 1,245 mg (31.1 mmol)/day and the ninetieth percentile of intake is 1,520 mg (38 mmol)/day (see Appendix D). Thus, the AI for boys ages 9 through 13 years of 1,300 mg (32.5 mmol)/day is slightly above the seventy-fifth percentile of calcium intake. For girls in this age range, the median calcium intake is 889 mg (22.2 mmol)/day, and the ninetieth percentile of intake is 1,313 mg (32.8 mmol)/day. Thus, the AI for girls ages 9 through 13 years of 1,300 mg (32.5 mmol)/day, is slightly below the ninetieth percentile of calcium intake based on the 1994 CSFII data.
For boys aged 14 through 18 years, the median calcium intake is 1,094 mg (27.4 mmol)/day, and the seventy-fifth percentile is 1,422 mg (35.6 mmol)/day. Thus, for boys ages 14 through 18 years, the AI for calcium of 1,300 mg (32.5 mmol)/day would fall between the median and seventy-fifth percentiles of intake. For girls in this age range, the median calcium intake was 713 mg (17.8 mmol)/day, and the ninetieth percentile was 1,293 mg (32.3 mmol)/day. Thus, for girls ages 14 through 18 years, the AI for calcium of 1,300 mg (32.5 mmol)/day would be close to the ninety-fifth percentile of intake based on the 1994 CSFII data.
Ages 19 through 30 Years
Peak Bone Mass
During the age span of 19 through 30 years, peak bone mass is achieved. Growth of long bones has ceased, but consolidation of bone mass continues. The age at which peak mass is achieved appears to vary with the skeletal site. Using single measures of BMC by DXA on 247 females aged 11 to 32 years, 92 percent of the total body bone mass observed was present by age 17.9 years and 99 percent by age 26.2 years (Teegarden et al., 1995). In a crosssectional study of 265 Caucasian females, only a 4 percent additional increase in total skeletal mass from age 18 to 50 years was reported (Matkovic et al., 1994). In a longitudinal study (with up to 5-year follow-up) of 156 women aged 18.5 to 26 years at entry and with a mean daily calcium intake from food and supplements of 786 mg (19.7 mmol), total body BMC increased by an average of 1.2 percent per year during the third decade of life, although within that age decade, the rate of gain slowed with age (Recker et al., 1992).
With regard to individual skeletal sites, no difference in subjects'