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DRI DIETARY REFERENCE INTAKES FOR Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride
nonfat dairy products to the high fruit and vegetable diet, which increased calcium intake as well, resulted in further lowering of blood pressure. Potassium intake was also greatly increased in both dietary regimens studied.
One study of hypertensive patients revealed low serum magnesium concentrations (Albert et al., 1958). No difference was detected in serum magnesium levels in other studies, however (Gadallah et al., 1991; Tillman and Semple, 1988). In patients with essential hypertension, free magnesium levels in erythrocytes were inversely related to both the systolic and diastolic blood pressure (Resnick et al., 1984). It is unclear whether the decrease in serum magnesium concentration was due to magnesium depletion or to pathophysiological events that lead to hypertension.
The possible relationship between hypertension and magnesium depletion is an important consideration, as the two coexist in a high proportion of individuals with diabetes and alcoholism (Resnick et al., 1991). However, the role of long-term dietary intake of magnesium in the prevalence of hypertension seen in the United States and Canada has not been established.
Skeletal Growth and Osteoporosis
Magnesium plays a major role in bone and mineral homeostasis and can also directly affect bone cell function as well as influence hydroxyapatite crystal formation and growth (Cohen, 1988).
Magnesium deficiency may be a risk factor for postmenopausal osteoporosis. Significant reductions in the serum magnesium and bone mineral content (BMC), but not red blood cell magnesium concentration or bone magnesium content, have been described in women with postmenopausal osteoporosis compared to age-matched controls (Reginster et al., 1989). No correlations were found in a 4-year clinical trial of magnesium intake and BMC in pre- and postmenopausal women consuming about 250 mg (10.4 mmol)/day of magnesium (Freudenheim et al., 1986), or in four of five skeletal sites measured in postmenopausal women also consuming an average of 253 mg ± 11 mg (10.5 ± 0.4 mmol)/day of magnesium (Angus et al., 1988).
In contrast, BMC of the radius in postmenopausal Japanese-American women was weakly positively correlated with magnesium intake (Yano et al., 1985), while elderly women who consumed less than 187 mg (7.8 mmol)/day had a significantly lower bone mineral density (BMD) compared with women whose average magnesium intake from diet was more than 187 mg (7.8 mmol)/day (Tucker et al., 1995).