COMT and osteoporosis: Indeed, treatment with L-DOPA, the main bioactive compound in MSM, has been associated with osteoporosis in mice (Ung et al. 2012) probably through L-DOPA breakdown by catechol-O-methyltransferase inducing formation of homocysteine (Postuma and Lang 2004), a high systemic level of which causes osteoporosis and bone fractures mediated by impaired collagen cross-linking (Van Meurs et al. 2004).