Acute benefits of the microbial-derived isoflavone metabolite equol on arterial stiffness in men prospectively recruited according to equol producer phenotype: A double-blind randomized controlled trial

Sara Hazim, Peter J. Curtis, Manuel Y. Schär, Luisa M. Ostertag, Colin D. Kay, Anne Marie Minihane, Aedín Cassidy*

*Corresponding author for this work

Research output: Contribution to journalArticle

67 Citations (Scopus)
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Abstract

Background: There is much speculation with regard to the potential cardioprotective benefits of equol, a microbial-derived metabolite of the isoflavone daidzein, which is produced in the large intestine after soy intake in 30% of Western populations. Although cross-sectional and retrospective data support favorable associations between the equol producer (EP) phenotype and cardiometabolic health, few studies have prospectively recruited EPs to confirm this association. Objective: The aim was to determine whether the acute vascular benefits of isoflavones differ according to EP phenotype and subsequently investigate the effect of providing commercially produced S-(-)equol to non-EPs. Design: We prospectively recruited male EPs and non-EPs (n = 14/group) at moderate cardiovascular risk into a double-blind, placebocontrolled crossover study to examine the acute effects of soy isoflavones (80-mg aglycone equivalents) on arterial stiffness [carotid-femoral pulse-wave velocity (cfPWV)], blood pressure, endothelial function (measured by using the EndoPAT 2000; Itamar Medical), and nitric oxide at baseline (0 h) and 6 and 24 h after intake. In a separate assessment, non-EPs consumed 40 mg S-(-) equol with identical vascular measurements performed 2 h after intake. Results: After soy intake, cfPWV significantly improved in EPs at 24 h (cfPWV change from 0 h: isoflavone, -0.2 ± 0.2 m/s; placebo, 0.6 ± 0.2 m/s; P < 0.01), which was significantly associated with plasma equol concentrations (R = -0.36, P = 0.01). No vascular effects were observed in EPs at 6 h or in non-EPs at any time point. Similarly, no benefit of commercially produced S-(-)equol was observed in non-EPs despite mean plasma equol concentrations reaching 3.2 μmol/L. Conclusions: Acute soy intake improved cfPWV in EPs, equating to an 11-12% reduced risk of cardiovascular disease if sustained. However, a single dose of commercially produced equol had no cardiovascular benefits in non-EPs. These data suggest that the EP phenotype is critical in unlocking the vascular benefits of equol in men, and long-term trials should focus on confirming the implications of EP phenotype on cardiovascular health.

Original languageEnglish
Pages (from-to)694-702
Number of pages9
JournalAmerican Journal of Clinical Nutrition
Volume103
Issue number3
DOIs
Publication statusPublished - 03 Feb 2016

Keywords

  • Arterial stiffness
  • CVD risk
  • Equol producer phenotype
  • Flavonoids
  • Isoflavone
  • Vascular function

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics

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