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DRI DIETARY REFERENCE INTAKES FOR Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride
etary magnesium intake in males of 380 mg (15.8 mmol)/day and 300 mg (12.5 mmol)/day in females. The study of intracellular magnesium by Touitou and coworkers (1987) suggests that the average requirement would be approximately 240 mg [10 mmol]/day). The study by Paolisso and colleagues (1992) found that in elderly subjects, an average dietary magnesium intake of 311 mg (13.0 mmol)/day was accompanied by a lower mean red blood cell magnesium concentration, which was not found in younger controls.
Given the uncertainty in the above methods, and the lack of balance data in healthy, elderly individuals to support the intake levels that may appear to be warranted based on the above analysis, estimates of magnesium requirements are suggested to remain at the level established for the other older adult age groups. These estimates would be within the range identified above as estimating the average requirement for elderly. It must be remembered, though, that urinary magnesium excretion has been shown to increase with age (Lowik et al., 1993, Martin, 1990), indicating a decrease in renal function.
EAR for Men
> 70 years
350 mg (14.6 mmol)/day
EAR for Women
> 70 years
265 mg (11.0 mmol)/day
Based on the 1994 CSFII intake data and adjusted for day-to-day variation (Nusser et al., 1996), the median magnesium intake for men aged > 70 years is 274 mg (11.4 mmol)/day (see Appendix D). The EAR of 350 mg (14.6 mmol)/day falls between the seventy-fifth percentile of magnesium intake of 334 mg (13.9 mmol)/day and the ninetieth percentile of intake of 394 mg (16.4 mmol)/day. For women in this same age range, the median magnesium intake is 205 mg (8.5 mmol)/day. As for men ages > 70 years, the magnesium EAR for women of 265 mg (11.0 mmol)/day falls between the seventy-fifth percentile of intake of 248 mg (10.3 mmol)/day and the ninetieth percentile of intake of 290 mg (12.1 mmol)/day.
Determination of the RDA for Magnesium: Ages > 70 Years
The variance in requirements could not be determined from the available data for either men or women ages > 70 years. Thus, a CV of 10 percent is assumed for the > 70 years age group. This results in an RDA for men ages > 70 years for magnesium of approximately 420 mg (17.5 mmol)/day and for women ages > 70 years of 320 mg (13.3 mmol)/day.