Many discussions on the health effects of cigarette smoking leave out a very important fact -- it can speed up the development of osteoporosis.
Several studies -- here is one example -- have found a link between cigarette consumption and decreased bone density.
Although one could argue that it may be behaviors and lifestyle choices common in smokers (i.e.: lack of physical activity) and not cigarettes themselves that may be the actual cause, there is no denying that smoking in and itself has a detrimental effect on bone health.
Nicotine, for example, inhibits calcitonin, a hormone that inhibits the dissolution of bone tissue.
Additionally, the massive amounts of free radicals created by smoking decrease levels of estrogen, consequently accelerating bone loss in women.