Smokers also tend to have a higher consumption of alcohol, may be less physically active, often have nutritional deficiencies, and tend to have an earlier menopause than non-smokers. These characteristics place many smokers at an increased risk for osteoporosis apart from their tobacco consumption. While the association between tobacco use and decreased bone density is fairly strong, the results are less consistent when fractures are considered. Most studies suggest at least a slight association between cigarette smoking and fracture, especially hip fracture and vertebral fracture. Not all studies have found such a relationship, however.
Studies have yet to demonstrate an association between tobacco use and forearm fractures.
In an arm of the Framingham study, Kiel and colleagues found that smoking use did not increase hip fracture risk in women. Importantly, the study also concluded that while estrogen replacement protected women from fracture, this protective effect was eliminated in women on estrogen replacement who smoked. Kiel's results support an anti-estrogenic effect of cigarette smoking that is consistent with the conclusions of other researchers. For example, smokers are less likely to develop uterine cancer, fibrocystic disease and fibroadenoma. Each of these conditions is believed to be related to estrogenic stimulation.