Association between equol production and bone turnover

Around 80 % of isoflavones in soybean are daidzein and genistein, and daidzein is converted to equol in intestinal flora. Although Genistein has a most potent biological effect among natural forms of isoflavones, equol has more potent than genistein. Since isoflavones have structural similarity to estrogen, association between equol production and bone turnover was investigated. One hundred and thirty‐nine subjects were recruited with informed consent, and twenty‐two of them were male and eighteen of female workers were postmenopause. No statistical differences were observed in age, daily soy product intake, bone alkaline phosphatase (BAP), carboxylated osteocalcin (Gla), undercarboxylated osteocalcin (Glu), deoxypridinoline (DPD), type I collagen crosslinked N‐telopeptides (NTX) and bone mineral parameter (OSI) between equol producers and non‐producers. When they were divided into four groups according to the estrogen receptor polymorphism (ERα) and equol production, interactional effect in Glu was observed. Moreover, when estrogen receptor polymorphism was taken into account, equol producers who have ERα pp allele, but not PP & Pp, significantly reduced the risk of bone mineral loss. Thus, it is suggested that production of equol may affect bone turnover. This study was supported in part by a Research Project Grant (No. 17‐501) from Kawasaki Medical School.