The purpose of the research is to determine if nitrates, a group of drugs that are widely available, inexpensive, and commonly used to treat chest pain or angina, can prevent osteoporosis in women. If the researchers find that nitrates prevent osteoporosis, a widely available, inexpensive treatment for osteoporosis prevention that does not have any long term side effects would have been identified. This will improve the health of patients with osteoporosis worldwide.