Pharmacokinetic Comparison of Soy Isoflavone Extracts in Human Plasma

Abstract

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 isoflavones and glucose metabolism in menopausal women: A systematic review and meta‐analysis of randomized controlled trials

“…Some studies have described that genistein presented higher bioavailability than daidzein , while others reported the contrary . In some studies, no differences in bioavailability were observed between daidzein and genistein .…”

Ameliorative Effect of Daidzein on Cisplatin‐Induced Nephrotoxicity in Mice via Modulation of Inflammation, Oxidative Stress, and Cell Death

“…Whole soy and its constituent daidzein have a positive effect on renal function in a clinical trial [ 7 ]. Pharmacokinetics of daidzein in human, mouse, and rat demonstrates its presence as glucuronides [ 13 , 14 ]. Comparative pharmacokinetics of traditional Chinese medicine Nao Mai Tong in a rat study also demonstrates the presence of daidzein [ 15 ].…”

Botanicals and Their Bioactive Phytochemicals for Women’s Health

“…Fortunately, no estrogenic effects on the endometrium or vagina were reported in these studies with up to 2 years of use. The poor bioavailability of genistein and daidzein from soy may explain the variable and relatively modest if any effects on menopausal symptoms ( Yang et al, 2012 ; Rodriguez-Morato et al, 2015 ).…”