Individuals with high levels of homocysteine in their blood have been found to have an increased risk of hip fracture, particularly among men. The risk for hip fracture was almost four times higher in men and 1.9 times higher in women in the highest quartile of serum homocysteine levels compared to those in the lowest quartile. One potential explanation for this association is that homocysteine may disrupt the formation of cross-links in collagen, which could contribute to the development of osteoporosis. Interestingly, this relationship between homocysteine levels and fracture risk appeared to be independent of other factors that are known to contribute to fracture risk, including bone mineral density.