title: Soy isoflavones increase preprandial peptide YY (PYY), but have no effect on ghrelin and body weight in healthy postmenopausal women.
abstract: BACKGROUND
  Soy isoflavones show structural and functional similarities to estradiol. Available data indicate that estradiol and estradiol-like components may interact with gut "satiety hormones" such as peptide YY (PYY) and ghrelin, and thus influence body weight. In a randomized, double-blind, placebo-controlled, cross-over trial with 34 healthy postmenopausal women (59 +/- 6 years, BMI: 24.7 +/- 2.8 kg/m2), isoflavone-enriched cereal bars (50 mg isoflavones/day; genistein to daidzein ratio 2:1) or non-isoflavone-enriched control bars were consumed for 8 weeks (wash-out period: 8-weeks). Seventeen of the subjects were classified as equol producers. Plasma concentrations of ghrelin and PYY, as well as energy intake and body weight were measured at baseline and after four and eight weeks of each intervention arm.
  
  
  RESULTS
  Body weight increased in both treatment periods (isoflavone: 0.40 +/- 0.94 kg, P < 0.001; placebo: 0.66 +/- 0.87 kg, P = 0.018), with no significant difference between treatments. No significant differences in energy intake were observed (P = 0.634). PYY significantly increased during isoflavone treatment (51 +/- 2 pmol/L vs. 55 +/- 2 pmol/L), but not during placebo (52 +/- 3 pmol/L vs. 50 +/- 2 pmol/L), (P = 0.010 for treatment differences, independent of equol production). Baseline plasma ghrelin was significantly lower in equol producers (110 +/- 16 pmol/L) than in equol non-producers (162 +/- 17 pmol/L; P = 0.025).
  
  
  CONCLUSIONS
  Soy isoflavone supplementation for eight weeks did not significantly reduce energy intake or body weight, even though plasma PYY increased during isoflavone treatment. Ghrelin remained unaffected by isoflavone treatment. A larger and more rigorous appetite experiment might detect smaller differences in energy intake after isoflavone consumption. However, the results of the present study do not indicate that increased PYY has a major role in the regulation of body weight, at least in healthy postmenopausal women.
authors.affiliation: German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany. m.weickert@dife.de
authors.forename: Martin O
authors.initials: MO
authors.lastname: Weickert
authors.forename: Manja
authors.initials: M
authors.lastname: Reimann
authors.forename: Bärbel
authors.initials: B
authors.lastname: Otto
authors.forename: Wendy L
authors.initials: WL
authors.lastname: Hall
authors.forename: Katherina
authors.initials: K
authors.lastname: Vafeiadou
authors.forename: Jesper
authors.initials: J
authors.lastname: Hallund
authors.forename: Marika
authors.initials: M
authors.lastname: Ferrari
authors.forename: Duncan
authors.initials: D
authors.lastname: Talbot
authors.forename: Francesco
authors.initials: F
authors.lastname: Branca
authors.forename: Susanne
authors.initials: S
authors.lastname: Bügel
authors.forename: Christine M
authors.initials: CM
authors.lastname: Williams
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Zunft
authors.forename: Corinna
authors.initials: C
authors.lastname: Koebnick
mesh_terms: D000368:Aged; D001835:Body Weight / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005215:Fasting / Q000502:physiology*; D005260:Female; D054439:Ghrelin; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage*; D008875:Middle Aged; D036361:Peptide Hormones / Q000097:blood*; D019894:Peptide YY / Q000097:blood*; D017698:Postmenopause / Q000097:blood*; D045730:Soy Foods
chemical_list: D054439:Ghrelin; D007529:Isoflavones; D036361:Peptide Hormones; D019894:Peptide YY