Soya--a dietary source of the non-steroidal oestrogen equol in man and animals.
The dietary origin of the weak oestrogen equol (7-hydroxy-3-(4'-hydroxyphenyl)-chroman) present in human urine has been investigated using gas chromatography-mass spectrometry. Feeding experiments with different food constituents and monitoring the urinary excretion of equol revealed that soya food yields more than 0.1 mg urinary equol/g flour ingested. From this source the glucoside of daidzein (4',7-dihydroxyisoflavone) has been isolated and identified as a precursor of equol. Both equol and daidzein were characterized as monoglucuronide conjugates in human urine and the concentration of urinary equol exceeded the concentrations of the classical oestrogens by 100- to 1000-fold after ingestion of a single meal containing soya protein. The potential biological significance of this result is discussed.
D000328:Adult; D000818:Animals; D001578:Benzopyrans / Q000652:urine*; D002839:Chromans / Q000032:analysis / Q000652:urine*; D004032:Diet; D060754:Equol; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007529:Isoflavones / Q000032:analysis; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013025:Glycine max / Q000032:analysis / Q000378:metabolism*
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D001578:Benzopyrans; D002839:Chromans; D007529:Isoflavones; D060754:Equol; C004742:daidzein