between the twenty-fifth percentile and the median intake for girls ages 9 through 13 years.

Determination of the RDA for Magnesium: Ages 9 through 13 Years

The variance in requirements cannot be determined from the data available. Thus, a CV of approximately 10 percent is assumed for each EAR. This results in an RDA of 240 mg (10 mmol)/day for both boys and girls ages 9 through 13 years.

RDA for Boys

9 through 13 years

240 mg (10 mmol)/day

RDA for Girls

9 through 13 years

240 mg (10 mmol)/day

EAR Summary: Ages 14 through 18 Years

Given the available data, it seems appropriate to conclude that for older adolescents, the average magnesium requirement is greater than 5 mg (0.21 mmol)/kg/day. The average additional magnesium intake necessary to result in a net retention of about 8 mg (0.33 mmol)/day is about 16 mg (0.67 mmol) or 0.3 mg (0.12 mmol)/kg/day for a 55 kg adolescent based on an assumed absorption rate of 40 percent (range 30 to 50 percent) (Abrams et al., 1997). Less than 5 mg (0.21 mmol)/kg/day of magnesium resulted in negative balances in all boys when they consumed the lower protein intake in the Schwartz et al. (1973) study and in most of the older girls in the Greger et al. (1978) study. In the 2-year Schwartz et al. (1973) study, even for subjects on the high protein diet, average magnesium retention was 6 and 15 mg (0.25 and 0.63 mmol)/day for each year, respectively, at the 240 mg (10 mmol)/day intake level. Thus, the EAR is estimated to be 5.3 mg (0.22 mmol)/kg/day in 14- through 18-year-old boys and girls, given that the highest average level provided in any of the five long-term balance studies (Andon et al., 1996; Greger et al., 1978, 1979; Schwartz et al., 1973, Sojka et al., 1997) was 5.6 mg (0.23 mmol)/kg/day. This resulted in slightly negative nitrogen balances in the older children studied (Greger et al., 1978; Schwartz et al., 1973). An average intake of 6.4 mg (0.27 mmol)/kg/day resulted in net positive magnesium retention in the more recent stable isotope study of Abrams et al. (1997). Thus, for boys ages 14 through 18 years, with reference weight 64 kg (Table 1-3), the EAR for magnesium is 340 mg (14.2 mmol)/day, and for girls in this age range with reference weight of 57 kg, the EAR is 300 mg (12.5 mmol)/day.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement