Tocotrienols Regulate Bone Loss through Suppression on Osteoclast Differentiation and Activity: A Systematic Review

BACKGROUND: There are accumulating studies reporting that vitamin E in general exhibits bone protective effects. This systematic review, however discusses the effects of a group of vitamin E isomers, tocotrienols in preventing bone loss through osteoclast differentiation and activity suppression. OBJECTIVE: This review is aimed to discuss the literature reporting the effects of tocotrienols on osteoclasts, the cells specialized for resorbing bone. RESULTS: Out of the total 22 studies from the literature search, only 11 of them were identified as relevant, which comprised of eight animal studies, two in vitro studies and only one combination of both. The in vivo studies indicated that tocotrienols improve the bone health and reduce bone loss via inhibition of osteoclast formation and resorption activity, which could be through regulation of RANKL and OPG expression as seen from their levels in the sera. This is well supported by data from the in vitro studies demonstrating the suppression of osteoclast formation and resorption activity following treatment with tocotrienol isomers. CONCLUSION: Thus, tocotrienols are suggested to be potential antioxidants for prevention and treatment of bone-related diseases characterized by increased bone loss.