Magnesium Supplementation to Prevent Bone Loss

Inclusion Criteria: Healthy ambulatory men and women between the ages of 55-75 years Women at least 5 years after menopause Exclusion Criteria: Inability to give informed consent in accordance with institutional guidelines Creatinine greater than or equal to 2 mg/dl, since magnesium is excreted by the kidneys Diarrhea or loose frequent stools (> 2 a day) at least 3 days/ week in last 3 months Use within 12 months of estrogen, bisphosphonates, calcitonin, or raloxifene Current use of loop diuretics Use within 12 months of corticosteroids History of hyperparathyroidism, hyperthyroidism, or osteomalacia within past 12 month Vitamin D deficient as measured by 25-hydroxyvitamin D outside of the normal range Magnesium supplementation of greater than 250 mg/day Calcium supplementation of greater than 1500 mg/day Conditions which, in the opinion of the investigator, would interfere with the evaluation of BMD at the spine including severe scoliosis, osteophytosis and lumbar fusion Bilateral hip replacement BMD at the lumbar spine L2-L4 of less than 0.859g/cm2 for women or 0.895 g/cm2 in men; or total hip less than 0.698 g/cm2 for women or 0.731 g/cm2 for men; or femoral neck less than 0.627 g/cm2 for women or 0.658 g/cm2 for men This represents a T-score of less than -2 at each site High serum calcium on screening blood test