title: Urinary isoflavonoids and risk of coronary heart disease.
abstract: BACKGROUND
  Whether soy food consumption may protect against coronary heart disease (CHD) remains controversial. No previous study has used biomarkers of soy intake in assessing the relationship between soy consumption and CHD. Biomarkers that reflect both intake and metabolism may be more informative than self-reports of dietary intake.
  
  
  METHODS
  We examined associations of urinary isoflavonoids, a biomarker of soy or soy isoflavone intake, with risk of CHD in a case-control study nested within two prospective cohort studies of Chinese adults in Shanghai. Cases were defined as subjects with no history of CHD at baseline who developed incident CHD during follow-up. Control subjects were randomly selected from those who remained free of CHD and matched to cases by sex, age, date and time of sample collection and antibiotic use. Baseline urinary isoflavonoids (daidzein, genistein, glycitein, equol, O-desmethylangolensin, dihydrodaidzein and dihydrogenistein) were compared between cases (n = 377) and control subjects (n = 753). Conditional logistic regression was used to evaluate the associations.
  
  
  RESULTS
  Total urinary isoflavonoids were not associated with CHD in either women or men. However, urinary equol excretion showed a significant inverse association with CHD in women. The adjusted odds ratios (95% confidence intervals) for CHD across increasing quartiles of equol levels in women were 1 (reference), 0.61 (0.32, 1.15), 0.51 (0.26, 0.98) and 0.46 (0.24, 0.89) (P = 0.02 for trend).
  
  
  CONCLUSIONS
  Our study suggests for the first time that equol, a bioactive metabolite of soy isoflavone daidzein, may be inversely associated with risk of CHD in women.
authors.affiliation: Department of Medicine, Vanderbilt Epidemiology Center, Vanderbilt University School of Medicine, Nashville, TN 37203-1738, USA. xianglan.zhang@vanderbilt.edu
authors.forename: Xianglan
authors.initials: X
authors.lastname: Zhang
authors.forename: Yu-Tang
authors.initials: YT
authors.lastname: Gao
authors.forename: Gong
authors.initials: G
authors.lastname: Yang
authors.forename: Honglan
authors.initials: H
authors.lastname: Li
authors.forename: Qiuyin
authors.initials: Q
authors.lastname: Cai
authors.forename: Yong-Bing
authors.initials: YB
authors.lastname: Xiang
authors.forename: Bu-Tian
authors.initials: BT
authors.lastname: Ji
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Franke
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Xiao-Ou
authors.initials: XO
authors.lastname: Shu
mesh_terms: D000328:Adult; D000368:Aged; D000428:Alcohol Drinking / Q000453:epidemiology; D015415:Biomarkers; D001837:Body Weights and Measures; D002681:China; D003327:Coronary Disease / Q000453:epidemiology* / Q000652:urine*; D004032:Diet; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000652:urine*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D045730:Soy Foods
chemical_list: D015415:Biomarkers; D007529:Isoflavones; C065753:isoflavanone