All study participants will receive a supply of calcium and vitamin D to take at home, for general bone health. These supplements should be taken by mouth, twice a day for 12 months. If you do not tolerate the supplements provided by the research study, you may take another brand of calcium/Vitamin D that you buy over-the-counter. The doses that you take each time (twice daily) should be 500 mg for calcium and 400 International Units (IU) for Vitamin D.