Osteoclasts reabsorb the existing bone while the new bone is formed by osteoblasts. There are many factors that affect bone metabolism. It is affected by age, activity, dietary minerals, vitamin D, sex hormones, thyroid metabolism, parathyroid hormones, and many other factors. The calcium intake is thought to influence the bone loss due to aging. However what is not clear is its effects greater on the achievement of peak bone mass or on the moderation of subsequent bone loss.
Exercise is believed to be important in maintaining the maximal bone density.
Estrogen deficiencies are associated with an accelerated bone loss. Being female 2. Advancing age 3. A family history of osteoporosis 5. An inactive lifestyle 7.