Fermentation Improves the Preventive Effect of Soybean Against Bone Loss in Senescence‐Accelerated Mouse Prone 6

Abstract Osteopenia is a preclinical phase of osteoporosis, it occurs naturally with aging and increases the risk of bone fractures in elderly males. Previous studies have revealed the beneficial effects of soybean on preventing bone loss due to its isoflavone contents. Fermentation alters the soybean isoflavone contents, that is, isoflavone glucosides is hydrolyzed into aglycones. However, it is not clear how these alterations influences the preventive effect of soybean on bone loss. In this study, we fed senescence‐accelerated mouse prone 6 (SAMP6), a model of senile osteopenia, with an equal dosage of nonfermented soybean (NS) or fermented soybean, Doenjang (DJ) for 18 weeks. Mice supplemented with DJ showed 1.13‐fold higher bone densities and 1.06‐fold longer relative bone lengths than those of osteopenic SAMP6 mice old control (OC), while NS‐supplemented mice showed no significant improvement. Supplementation with DJ effectively prevented bone loss in the osteopenia model by the improvement of bone formation and reduction of osteoclastogenesis. In addition, we discovered that DJ increased osteogenesis in SAMP6 mice via BMP2‐Smad‐Runx2 signaling. These results suggest that the fermentation process could enhance bone loss prevention by soybean and dietary supplementation with fermented soybeans may be beneficial for bone health. Practical Application Soybean fermentation improved the preventive effects of soybean on bone loss. Therefore, the consumption of fermented soybean, Doenjang, is a potential alternative for aging‐related bone loss therapy.