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ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Healthy Body Weight Research » Research » Publications at this Location » Publication #190781
Title: Magnesium requirements: new estimations for men and women by cross-sectional statistical analyses of metabolic magnesium balance data

Author
item Hunt, Curtiss
item JOHNSON, LUANN - UNIV OF NORTH DAKOTA

Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2006
Publication Date: 10/1/2006
Citation: Hunt, C., Johnson, L.K. 2006. Magnesium requirements: new estimations for men and women by cross-sectional statistical analyses of metabolic magnesium balance data. American Journal of Clinical Nutrition. 84:843-52.

Interpretive Summary: Persons who do not have enough magnesium in their diets may be at higher risk for developing osteoporosis or diseases of the heart and arteries. There is not enough scientific information available to recommend how much magnesium should be eaten every day on average to replace the magnesium that is lost every day in the urine, feces, and sweat. Therefore, we examined the information from 28 studies with adults (137 women who were between 19 and 77 years of age; 91 men who were between 19 and 65 years of age). The studies were conducted at the USDA ARS Grand Forks Human Nutrition Research Center over a period of 25 years. The scientists carefully measured all of the magnesium that each of these persons consumed and all of the magnesium that was excreted in the urine and feces. A very amount of magnesium was lost in the sweat (in young men, only 4 mg per day on average). After examining all of the information, it was estimated that adults need to consume about 186 milligrams of magnesium every day on average to replace the magnesium that is lost from the body. The age or sex of the person did not change the amount of magnesium that was needed to keep the body in magnesium balance. The information from this study greatly expands the information currently available on magnesium balance and should be useful in making better estimates of how much dietary magnesium adults require to maximize their health status.

Technical Abstract: Low intakes of magnesium (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]) comprising 616 data points 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 respective Estimated Average Requirements (EARs) or exceeded respective 99th %tiles of 1994 CSFII usual intakes of those elements (for Fe, above the UL). Daily intakes of Mg ranged between 87 and 598 mg. The relation between intake (in mg/d, mg/kg/d, or mg/kcal/d) and Mg output (fecal + urinary excretion) was investigated using a linear model. 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. The models predicted neutral Mg balance (B) at Mg intakes (M) of 186 mg/d (B = 27.4 + 0.853M), 2.71 mg/d per kg (B = 0.46 + 0.83M), or 0.84 mg/kcal (B = 0.016 + 0.806M). The findings augment the meager information available for calculating the EAR for Mg and suggest a lower Mg requirement for healthy men and women than estimated previously.