title: Resistant starch promotes equol production and inhibits tibial bone loss in ovariectomized mice treated with daidzein.
abstract: Daidzein is metabolized to equol in the gastrointestinal tract by gut microflora. Equol has greater estrogenic activity than genistein and daidzein, with its production shown to be promoted by dietary fiber. It is known that resistant starch (RS) is not absorbed in the proximal intestine and acts as dietary fiber in the colon. In this study, we investigated the combined effects of daidzein and RS intake on equol production, bone mineral density, and intestinal microflora in ovariectomized (OVX) mice. Female mice of the ddY strain, aged 8 weeks, were either sham operated (n = 6) or OVX. The OVX mice were randomly divided into 5 groups: OVX control (n = 6), OVX fed 0.1% daidzein-supplemented diet (OVX + Dz, n = 8), OVX fed 0.1% daidzein- and 12% RS-supplemented diet (OVX + Dz + RS, n = 8), OVX fed 12% RS-supplemented diet (OVX + RS, n = 8), and OVX who received daily subcutaneous administration of 17 β-estradiol (n = 6). After 6 weeks, urinary equol concentration was significantly higher in the OVX + Dz + RS group than in the OVX + Dz group. The bone mineral density of the whole tibia was higher in the OVX + Dz +RS group compared with the OVX + Dz group. The occupation ratios of Bifidobacterium spp in the cecal microflora in groups fed RS were significantly higher than those in the other groups. The present study demonstrated that RS may increase the bioavailability of daidzein.
authors.affiliation: Food Function and Labeling Program, National Institute of Health and Nutrition, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Tousen
authors.forename: Fumiko
authors.initials: F
authors.lastname: Abe
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Ishida
authors.forename: Mariko
authors.initials: M
authors.lastname: Uehara
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Ishimi
mesh_terms: D000818:Animals; D015519:Bone Density / Q000187:drug effects; D050071:Bone Density Conservation Agents / Q000627:therapeutic use; D001851:Bone Diseases, Metabolic / Q000178:diet therapy / Q000188:drug therapy* / Q000378:metabolism; D002432:Cecum / Q000187:drug effects / Q000382:microbiology; D003131:Combined Modality Therapy; D004357:Drug Synergism; D060754:Equol / Q000378:metabolism*; D005260:Female; D007529:Isoflavones / Q000097:blood / Q000627:therapeutic use* / Q000652:urine; D051379:Mice; D010052:Ovariectomy; D013213:Starch / Q000378:metabolism / Q000494:pharmacology*; D013977:Tibia / Q000187:drug effects* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D050071:Bone Density Conservation Agents; D007529:Isoflavones; D060754:Equol; C004742:daidzein; D013213:Starch