title: Dietary soy protein and isoflavones: minimal beneficial effects on bone and no effect on the reproductive tract of sexually mature ovariectomized Sprague-Dawley rats.
abstract: OBJECTIVE
  The present study was conducted to determine the effects of dietary soy protein and isoflavones on bone and the reproductive tract in the absence of the ovary.
  
  
  METHODS
  Three-month-old Sprague-Dawley rats (n = 56) were either sham-operated or ovariectomized and then fed diets containing casein or soy protein +/- isoflavone extract for 12 weeks. The amounts of casein, soy protein, and extract (per kg diet) in each group were as follows: (1) Ovariectomy, 200 g of casein; (2) Ovariectomy+low soy, 100 g of casein + 100 g of soy protein; (3) Ovariectomy+high soy, 200 g of soy protein; (4) Ovariectomy+low extract, 200 g of casein + 17.2 g of extract; (5) Ovariectomy+high extract, 200 g of casein + 34.4 g of extract; (6) Ovary intact, 200 g of casein; (7) Ovariectomy+estradiol-17beta, 200 g of casein. Diet consumption, body weight, uterine weight, urine deoxypyridinoline, and bone mineral density of the femur and lumbar vertebrae were measured. The femur rigidity was evaluated by histomorphometry. The reproductive tract (uterus, vagina, and cervix) was studied histologically.
  
  
  RESULTS
  The Ovariectomy group showed significant increases in body weight, diet consumption, and deoxypyridinoline, decreases in uterine weight and bone mineral density, and negative changes in histomorphometry compared with the Ovary intact group. Neither soy protein nor extract diets abrogated these alterations, except for the Ovariectomy+high extract group that showed statistically significant positive changes in histomorphometric parameters. There were no histological differences in the reproductive tract among Ovariectomy, Ovariectomy+soy, and Ovariectomy+extract groups. The estradiol-17beta replacement abrogated ovariectomy-induced alterations.
  
  
  CONCLUSIONS
  Dietary intake of isoflavones by sexually mature ovariectomized rats has a minimal beneficial effect on bone with no effect on the reproductive tract.
authors.affiliation: Department of Animal Sciences, University of Illinois, Urbana, IL 61801, USA. jbahr@uiuc.edu
authors.forename: Janice M
authors.initials: JM
authors.lastname: Bahr
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nakai
authors.forename: Alexander
authors.initials: A
authors.lastname: Rivera
authors.forename: Jane
authors.initials: J
authors.lastname: Walsh
authors.forename: Glenda L
authors.initials: GL
authors.lastname: Evans
authors.forename: Sutada
authors.initials: S
authors.lastname: Lotinun
authors.forename: Russell T
authors.initials: RT
authors.lastname: Turner
authors.forename: Molly
authors.initials: M
authors.lastname: Black
authors.forename: Elizabeth H
authors.initials: EH
authors.lastname: Jeffery
mesh_terms: D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000187:drug effects; D004032:Diet; D004195:Disease Models, Animal; D004958:Estradiol / Q000008:administration & dosage; D005260:Female; D005270:Femur Head; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage*; D008159:Lumbar Vertebrae; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control*; D010052:Ovariectomy; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D030262:Soybean Proteins / Q000008:administration & dosage*; D014599:Uterus / Q000187:drug effects
chemical_list: D007529:Isoflavones; D010936:Plant Extracts; D030262:Soybean Proteins; D004958:Estradiol