In summary, this study demonstrated for the first time that delphinidin possesses a potent inhibitory effect against RANKL-mediated osteoclastogenesis via downregulation of osteoclastogenic factors such as Nfκb, c-fos and Nfatc1. Oral administration of delphinidin showed a preventive effect on bone loss in osteoporosis model mice. The gene discussed is FOS; the disease is osteoporosis.