From The "Now You Know" Files

The Research On Creatine And Bone Health

Creatine supplementation may be particularly beneficial for postmenopausal women since the hormonal changes of menopause can contribute to muscle and bone loss. This puts women at a higher risk of developing osteoporosis.

However, separate research has found that supplemental creatine (combined with resistance training) can decrease the rate of bone loss in older men as well.

It seems to do this by increasing the activity of osteoblasts (cells involved in the bone formation), and since creatine can also help increase muscle mass, it may cause "greater muscle pull" on the bone during strength training, indirectly improving bone density.