Over 10 million adults in the United States have osteoporosis, and another 18 million have low bone mass, a risk factor for developing this disease. Each year, approximately 1.5 million fractures are associated with osteoporosis. Adequate intake of calcium and vitamin D is the current nutritional approach to preventing age-related bone loss. However, even with sufficient levels of these nutrients, bone loss can still occur. Too much acid in the body, caused by diet, aging, and protein metabolism, appears to be linked to loss of calcium via urine, bone loss, and muscle breakdown. Potassium citrate can neutralize acids. The purpose of this study is to determine the effect of various doses of potassium citrate on bone density and muscle mass in older, healthy adults.