title: Soy isoflavone supplementation improves longitudinal bone growth and bone quality in growing female rats.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of soy isoflavone on tibia length, bone mineral density (BMD), and structural parameters in growing female rats.
  
  
  METHODS
  Three-week-old female Sprague-Dawley rats were randomly assigned to four experimental groups: control (CON: distilled water gavage); low-dose isoflavone (low-IF: 10 mg/kg body weight [BW]/d gavage); high-dose isoflavone (high-IF: 50 mg/kg BW/d gavage); and 17 β-estradiol (E2: subcutaneous injection of 10 μg). All animals received a soy-free diet and vaginal opening was monitored daily. After an 8-wk treatment period, bone-related parameters (alkaline phosphatase [ALP], osteocalcin [OC], N-terminal telopeptide [NTx], bone length, failure load, stiffness, BMD, and structural parameters) were analyzed.
  
  
  RESULTS
  Serum ALP levels of the high-IF group were higher than those of the CON group (P < 0.05); however, serum OC levels of the high-IF group were lower than those of the CON, low-IF, and E2 groups (P < 0.05). The tibias and femurs of the low-IF group were longer than those of the CON and high-IF groups (P < 0.05). Bone volume, trabecular number, and BMD of trabecular bone of the high-IF and E2 groups were higher than those of the CON and low-IF groups (P < 0.05). The trabecular thickness of the high-IF group was higher than that of the CON and low-IF groups (P < 0.05). The failure load of the high-IF group was higher than those of the CON group (P < 0.05). Age and body weight at vaginal opening of the E2 group were significantly lower than those of the CON, low-IF, and high-IF groups (P < 0.05).
  
  
  CONCLUSIONS
  This study suggests that 8 wk of low-dose supplementation with soy isoflavone stimulates longitudinal bone growth. Additionally, high-dose supplementation with soy isoflavone may improve bone quality (BMD and structural parameters) in growing female rats.
authors.affiliation: Department of Medical Nutrition, Kyung Hee University, Yongin, Korea.
authors.forename: Hyejin
authors.initials: H
authors.lastname: Ahn
authors.affiliation: Department of Medical Nutrition, Kyung Hee University, Yongin, Korea; Research Institute of Medical Nutrition, Kyung Hee University, Seoul, Korea. Electronic address: Ypark@khu.ac.kr.
authors.forename: Yoo Kyoung
authors.initials: YK
authors.lastname: Park
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001835:Body Weight; D015519:Bone Density; D001846:Bone Development / Q000187:drug effects*; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005269:Femur / Q000187:drug effects*; D007529:Isoflavones / Q000494:pharmacology*; D015675:Osteocalcin / Q000097:blood; D010446:Peptide Fragments / Q000652:urine; D051381:Rats; D017207:Rats, Sprague-Dawley; D013025:Glycine max / Q000737:chemistry; D013977:Tibia / Q000187:drug effects*
chemical_list: D015415:Biomarkers; D007529:Isoflavones; D010446:Peptide Fragments; D015675:Osteocalcin; D004958:Estradiol; D000469:Alkaline Phosphatase
keywords: BMD; Bone structural parameters; Growing rats; Longitudinal bone growth; Soy isoflavone; Vaginal opening