title: Determination of the isoflavonoids genistein and daidzein in biological samples by gas chromatography-mass spectrometry.
abstract: BACKGROUND
  The marked differences in the incidences of both breast and prostate cancer between the East and the West have been attributed to habitual diet. Traditionally, Japanese and Far Eastern people in general consume large quantities of soya and soya-derived foodstuffs. Diphenolic soya phytoestrogens have weak oestrogenic and anti-oestrogenic properties and have been implicated in preventing or limiting the early processes associated with breast and prostate carcinogenesis.
  
  
  METHODS
  We have developed a gas chromatography-mass spectrometry procedure that is suitable for measurement of the phytoestrogens daidzein and genistein in serum, urine and tissue samples.
  
  
  RESULTS
  In serum samples of Japanese subjects mean (standard deviation) concentrations of daidzein [men, 281 (375.5) nmol/L; women, 246 (369.4) nmol/L] and genistein (men, 493 (604.4) nmol/L; women, 502 (717.6) nmol/L] were approximately 15 times higher than the mean levels achieved in British men [daidzein, 18.2 (20.4) nmol/L; genistein, 34.1 (27.2) nmol/L] and women [daidzein, 13.5 (11.6) nmol/L; genistein, 30.1 (31.2) nmol/L]. In pharmacokinetic studies of British subjects, maximum levels of daidzein and genistein were achieved within 6-8 h after the consumption of a cereal bar containing 20 mg of soya isoflavonoids; these levels were very similar to the mean levels achieved in normal Japanese subjects. Unlike serum, the mean daidzein concentration in urine from British subjects was higher than the mean genistein concentration (1.66 and 0.72 micromol per 24 h, respectively); following soy supplementation, urinary isoflavonoid levels were increased at least 10-fold.
  
  
  CONCLUSIONS
  Serum daidzein and genistein concentrations are lower in British subjects than in Japanese subjects; this may be due to dietary differences.
authors.affiliation: Tenovus Cancer Research Centre, University Hospital of Wales, Cardiff and Vale NHS Trust, Cardiff, UK.
authors.forename: Sara L
authors.initials: SL
authors.lastname: Pumford
authors.forename: Michael M
authors.initials: MM
authors.lastname: Morton
authors.forename: Atilla
authors.initials: A
authors.lastname: Turkes
authors.forename: Keith
authors.initials: K
authors.lastname: Griffiths
mesh_terms: D000328:Adult; D044466:Asian People; D001940:Breast / Q000737:chemistry; D004032:Diet; D004739:England; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D019833:Genistein / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D006801:Humans; D007529:Isoflavones / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics / Q000652:urine; D007564:Japan; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013025:Glycine max / Q000737:chemistry; D044465:White People
chemical_list: D007529:Isoflavones; C004742:daidzein; D019833:Genistein