Current Magnesium Requirements Much Too High

Am J Clin Nutr

The limited data that were used to establish the recommendations for magnesium intake for men and women prompted a new investigation that has demonstrated that the current requirements are much too high for healthy men and women (. 2006; 84: 843-852).

J Clin Nutr

Surprisingly, current government guidelines for magnesium—320 to 365 mg/day for women and 410 to 420 mg/ day for men—are based almost exclusively on a single study published 23 years ago (. 1984; 40:1380-1389).

This new, cross-sectional study investigated data on metabolic magnesium balance in 150 women (mean age, 51.3 years) and 93 men (mean age, 28.1 years) who were enrolled in a series of feeding studies conducted by the US Department of Agriculture. Comparison of data from the last 6 to 14 days of each dietary period from 27 individual original metabolic studies showed that daily intakes of magnesium ranged from 84 to 598 mg. Random coefficient models were then used to determine the relationship between magnesium intake and magnesium output (ie, fecal and urinary excretion).

Analysis showed that men and women would achieve neutral magnesium balance (ie, magnesium output that equals magnesium intake) at intake levels of 165 mg/day, regardless of age or gender.

Thus, the investigators write, “Compared with the existing EAR [estimated average requirement], the new estimate of the magnesium requirement is 35% to 48% lower for women and 50% to 53% lower for men.”

The findings that “the relation between magnesium intake and output is not affected by sex concur with earlier findings,” they add. As a result, gender-specific magnesium intake recommendations are likely unnecessary.