|Johnson, Luann - UNIV OF NORTH DAKOTA|
Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 2005
Publication Date: March 6, 2006
Citation: Hunt, C., Johnson, L.K. 2006. Estimation of magnesium requirements in men and women by cross-sectional statistical analyses of metabolic magnesium balance data [abstract]. FASEB J. 20(4):A182. Technical Abstract: Low intakes of Mg are associated with increased risk of both osteoporosis and cardiovascular disease. To provide new estimates of the average Mg requirement for men and women, we determined the dietary Mg intake required to maintain neutral Mg balance. Mg balance data (Mg intake - [fecal Mg + urinary Mg]) were collected from 228 subjects (females: n=137, weight=71.7±17.0 kg, age=50.5±17.7 y [range: 19-77 y]; males: n=91, weight=76.6±12.6 kg, age=27.8±7.9 y [range: 19-65 y]) who participated in 28 different tightly-controlled feeding studies conducted in a metabolic unit. Balance data from the last 6-14 d of each dietary period (minimum length of 28 d) of each study (1-9 observations per subject) were analyzed. Data were excluded if individual intakes of Ca, Cu, Fe, P, or Zn fell below the Estimated Average Requirements (EARs) or exceeded the 99th %tile of 1994 CSFII usual intakes (for Fe, above the UL). Daily intakes of Mg ranged between 87 and 598 mg. The relationship between intake (in mg/d or mg/kg/d) and balance was assumed to be linear. The Proc Mixed procedure in SAS was used to fit random coefficient models. Coefficients were included to allow for separate intercepts and slopes for men and women (to determine if the relationship differed by gender) but were removed for lack of statistical significance. The models predicted that neutral Mg balance (B) is maintained at Mg intakes (M) of 186 mg/d (163 and 209 mg/d for lower and upper 95% CI; B = -27.4 + 0.147M) or 2.64 mg/d/kg (2.31 or 2.97 mg/d/kg for lower and upper 95% CI; B = -29.2 + 11.1M). These findings augment the meager information available for calculating the EAR for Mg and suggest a lower Mg requirement for men and women than estimated previously.