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. Here, NFATC1 is linked to osteoporosis.