Impact of food matrix on isoflavone metabolism and cardiovascular biomarkers in adults with hypercholesterolemia

Abstract

The role of food matrix and gender on soy isoflavone metabolism and biomarkers of activity were examined in twenty free-living adults (34.7 ± 11.5 years old) with hypercholesterolemia (221.9 ± 18.7mg dL(-1)). In a randomized crossover design study, participants consumed soy bread (3 wk) or a soy beverage (3 wk) containing 20 g soy protein with 99 and 93 mg isoflavones aglycone equivalents per day, respectively. During soy bread intervention, women had significantly greater microbial metabolite excretion (P = 0.05) of isoflavonoids than men. In men, isoflavone metabolite excretion was not discernibly different between the two matrices. Significant reductions (P≤ 0.05) in triglycerides (24.8%), LDL cholesterol (6.0%), apolipoprotein A-I (12.3%), and lipid oxidative stress capacity (25.5%), were observed after soy food intervention. Our findings suggest that the food matrix significantly impacts soy isoflavone metabolism, particularly microbial metabolites in women.

Fig.1

Schematic diagram of the crossover study design comparing soy bread and soy beverage in women and men

Fig. 2

Representative HPLC chromatogram of isoflavones in soy food at 260 nm.

Fig. 3

Representative HPLC chromatogram of isoflavonoids in enzymatically digested urine of an equol and O-desmethylangolensin excretor at 270 nm

Fig.4

Comparison of daidzein metabolite profile in women (n=10) after soy beverage and soy bread intervention. DHD (dihydrodaidzein), equol, and ODMA (O-desmethylangolensin). Statistical significance (P ≤ 0.05) determined using Wilcoxon signed-rank test denoted with *.