She also reported that these women developed osteoporosis despite normal estrogen levels. It had previously been shown that maximum BMD occurs in most women around age 36. From a wide range of scientific research references, it is now clear that bone is living tissue, always been made, un-made and made anew. Estrogen slows this bone resorption process by slowing the action of osteoclasts. New bone formation is the result of osteoblasts.
Progesterone stimulates the action of osteoblasts.
The resulting BMD reflects the relative balance of these two hormones. Testosterone acts on bone in the same manner as progesterone. Thus, cortisone and especially the synthetic analogs lead to osteoporosis. By 1989, several studies confirmed that estrogen supplements increased the risk of breast cancer and that estrogen plus synthetic progestins increased it even more. Hormone balance appears to be the key.