(see Appendix D), which is slightly above the EAR of 265 mg (11.0 mmol)/day for women in this age range.

The variance in requirements cannot be determined from the data available for either men or women ages 51 through 70 years. Thus, a CV of 10 percent is assumed for both cases. This results in an RDA for men ages 51 through 70 years of approximately 420 mg (17.5 mmol)/day, and for women, 320 mg (13.3 mmol)/day.

Studies in this age group have aggregated data from both men and women, and therefore the requirements will be considered together. The greater numbers of individuals with chronic diseases in this population, and the comparative lack of research studies carried out in healthy free-living individuals in this age category, make estimation of requirements problematic.

Balance Studies. No magnesium balance studies that meet the criteria previously described have been reported in subjects over 70 years of age.

Magnesium Tolerance Tests. One study with 36 healthy elderly subjects (8 males and 28 females) 65 years of age and older (average age 73 ± 6 years), used magnesium tolerance testing as the indicator of adequacy (Gullestad et al., 1994). The self-selected dietary magnesium intake was estimated from food frequency questionnaires to be 380 ± 94 mg (15.8 ± 3.9 mmol)/day in the males and 300 ± 61 mg (12.5 ± 2.5 mmol)/day in the females. When corrected for body weight, this intake was similar in both sexes, 5.1 mg (0.21 mmol)/kg/day. Magnesium retention from the load given was 28 ± 16 percent in the elderly and was significantly greater than the 3.6 percent retention in a reference group of 53 subjects aged 55 ± 12 years. However, no correlation was seen between estimated magnesium intake and magnesium retention from the load