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J Agric Food Chem. 2015 Aug 12;63(31):6946-53. doi: 10.1021/acs.jafc.5b02891. Epub 2015 Aug 3.

Pharmacokinetic Comparison of Soy Isoflavone Extracts in Human Plasma.

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†Integrative Pharmacology and Systems Neuroscience Research Group, Neurosciences Research Program, IMIM (Hospital del Mar Medical Research Institute), Dr. Aiguader 88, Barcelona 08003, Spain.
‡Pompeu Fabra University (CEXS-UPF), Dr. Aiguader 88, Barcelona 08003, Spain.
§CIBER de Fisiopatologı́a Obesidad y Nutrición, Santiago de Compostela 15706, Spain.
#Department of Pharmacology, Therapeutics and Toxicology and Department of Psychiatry, Universitat Autònoma de Barcelona, UAB Campus, M Building, Barcelona 08193, Spain.
⊥Institut de Neuropsiquiatria i Adiccions, Adiction Unit and IMIM, Dr. Aiguader 88, Barcelona 08003, Spain.


The soy isoflavones daidzein and genistein produce several biological activities related to health benefits. A number of isoflavone extracts are commercially available, but there is little information concerning the specific isoflavone content of these products or differences in their bioavailability and pharmacokinetics. This study describes the development and validation of an analytical method to detect and quantify daidzein, genistein, and equol in human plasma using liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The method was applied in a crossover, randomized, bioavailability study. Twelve healthy volunteers were administered the same total isoflavones dose from two isoflavone supplement preparations (Super-Absorbable Soy Isoflavones (Life Extension, USA) and Fitoladius (Merck, Spain)). The pharmacokinetic parameters (AUC0-24/dose and Cmax/dose) of the isoflavones from the two preparations differed significantly. Such differences in bioavailability and kinetics may have relevant effects on the health benefits derived from their intake.


Soy isoflavone extracts; bioavailability; clinical trial; daidzein; equol; genistein; pharmacokinetics

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