What is the single most important factor in reducing osteoporosis in older women?

Vitamin D: Vitamin d level is the most important factor. You should have your vitamin d level checked and it should be 30 or greater. Second most important would be exercise. A bone density test will give an idea of your risk. You can also use the frax calculator to estimate your risk for an osteoporosis fracture: http://www.Shef.Ac.Uk/frax/tool.Jsp?Country=9.

Osteoporosis: There are many very good medications that can help control osteoporosis. The bone mineral density should be measured at least once a year while on therapy, or preferably every 6 months.