title: Identification and concentration of soy phytoestrogens in commercial dog foods.
abstract: OBJECTIVE
  To identify and determine the concentrations of phytoestrogens in commercial dog foods.
  
  
  METHODS
  24 commercial dog foods, including 12 moist or dry extruded commercial dog foods that contained soybeans or soybean fractions and 12 foods without any soybean-related ingredients listed on the label.
  
  
  METHODS
  Foods were analyzed for phytoestrogen content, including 4 isoflavones (genistein, glycitein, daidzein, and biochanin A), 1 coumestan (coumestrol), and 2 lignans (secoisolariciresinol and matairesinol) by use of acid-methanol hydrolysis and high-pressure liquid chromatography with UV-absorbance detection. Phytoestrogens were identified and quantified by reference to authentic standards.
  
  
  RESULTS
  Isoflavones, coumestans, and lignans were undetectable in diets that did not list soybean-related ingredients on the label. Only 1 of the 12 diets that included soybean or soybean fractions had undetectable concentrations of phytoestrogens and that product contained soy fiber. The major phytoestrogens were the isoflavones daidzein (24 to 615 microg/g of dry matter) and genistein (4 to 238 microg/g of dry matter).
  
  
  CONCLUSIONS
  Soybean and soybean fractions are commonly used ingredients in commercial dog foods. Dietary intake of phytoestrogens may have both beneficial and deleterious health effects. Our results indicated that certain commercial dog foods contain phytoestrogens in amounts that could have biological effects when ingested long-term.
authors.affiliation: Department of Clinical Studies-Philadelphia, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Rosario
authors.initials: R
authors.lastname: Cerundolo
authors.forename: Michael H
authors.initials: MH
authors.lastname: Court
authors.forename: Qin
authors.initials: Q
authors.lastname: Hao
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Michel
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004285:Dogs; D006868:Hydrolysis; D007529:Isoflavones / Q000032:analysis* / Q000737:chemistry*; D048789:Phytoestrogens; D028321:Plant Preparations / Q000032:analysis* / Q000737:chemistry*; D030262:Soybean Proteins / Q000032:analysis*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007529:Isoflavones; D048789:Phytoestrogens; D028321:Plant Preparations; D030262:Soybean Proteins