title: Prevalence of the equol-producer phenotype and its relationship with dietary isoflavone and serum lipids in healthy Chinese adults.
abstract: BACKGROUND
  Studies have suggested that daidzein-metabolizing phenotypes have beneficial effects on a range of health outcomes. We investigated the prevalence of equol producers and the relationship of equol phenotype with habitual isoflavone consumption and serum lipid concentrations in 200 Chinese adults in Beijing.
  
  
  METHODS
  After the baseline survey and dietary records, 200 healthy adults in Beijing were challenged with a soy-isoflavone supplement for 3 days; 24-hour urine samples were collected before and after the challenge. Isoflavones and their metabolites in urine were measured to determine equol phenotype. Serum lipids, uric acid, and other biochemical markers were also measured.
  
  
  RESULTS
  Only 26.8% of the participants excreted equol when on a regular diet, as compared with 60.4% after the challenge. After the challenge, urinary isoflavonoid excretion increased in all participants, while equol excretion increased only in equol producers. Isoflavone intake was correlated with urinary isoflavone (range r = 0.49-0.58, P < 0.01). As compared with nonproducers, equol producers were less likely to consume cereals (P < 0.001). There was no significant correlation between serum lipids and isoflavone intake. Serum lipids were not significantly affected by equol phenotype.
  
  
  CONCLUSIONS
  Urinary equol excretion was detected in about 25% of participants under their usual dietary conditions. Their potential to produce equol was increased after the challenge. Urinary isoflavone levels may serve as a useful biomarker for isoflavone intake in populations. We observed an association between equol phenotype and cereal intake. Our findings also suggest that dietary isoflavone intake has no significant effect on serum lipids in healthy participants, regardless of equol phenotype.
authors.affiliation: Department of Social Medicine & Health Education, School of Public Health, Peking University, Haidian District, Beijing, PR China.
authors.forename: Baohua
authors.initials: B
authors.lastname: Liu
authors.forename: Liqiang
authors.initials: L
authors.lastname: Qin
authors.forename: Aiping
authors.initials: A
authors.lastname: Liu
authors.forename: Shigeto
authors.initials: S
authors.lastname: Uchiyama
authors.forename: Tomomi
authors.initials: T
authors.lastname: Ueno
authors.forename: Xuetuo
authors.initials: X
authors.lastname: Li
authors.forename: Peiyu
authors.initials: P
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood / Q000652:urine; D002681:China; D004032:Diet; D060754:Equol; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage* / Q000652:urine; D008055:Lipids / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D015995:Prevalence; D013025:Glycine max; D055815:Young Adult
chemical_list: C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D015415:Biomarkers; D007529:Isoflavones; D008055:Lipids; D060754:Equol