Effects of soy isoflavones on endothelial function in healthy postmenopausal women.
OBJECTIVE
To evaluate the effects of soy isoflavone administration on endothelial function in healthy postmenopausal women.


METHODS
Sixty naturally postmenopausal women were randomly assigned to receive isoflavone or placebo tablets for 6 months. Endothelium-dependent vasodilatation was measured by brachial reactivity technique along with levels of plasma soluble intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, P-selectin and soluble thrombomodulin, von Willebrand factor, and tissue plasminogen activator. Differences between endothelium-dependent and endothelium-independent vasodilatation were assessed by evaluating brachial reactivity parameters after reactive hyperemia and after sublingual administration of nitroglycerin; furthermore, in the active group, the effect of isoflavones was also evaluated during the intra-arterial infusion of N-monomethyl-L-arginine. Serum levels of lipids [high-density lipoprotein and low-density lipoprotein cholesterol, triglycerides and lipoprotein(a)] and hemostatic factors (prothrombin, fibrinogen, plasminogen activator inhibitor-1, and fibrin D-dimer) were also measured. To confirm the absorption of isoflavones, their blood concentrations were determined.


RESULTS
Isoflavone treatment versus placebo was associated with a significant improvement in endothelium-dependent vasodilatation but had no impact on endothelial-independent arterial diameter and flow. Intra-arterial infusion of N-monomethyl-L-arginine inhibited the significant effect of isoflavones on endothelium-mediated vasodilatation. Furthermore, isoflavone group experienced statistically significant reductions in plasma concentrations of ICAM-1, VCAM-1, and E-selectin. Levels of soluble thrombomodulin, von Willebrand factor, tissue plasminogen activator, lipids, and hemostatic factors did not change significantly throughout the study in both groups.


CONCLUSIONS
Our findings suggest a positive influence of soy isoflavones on endothelial function in healthy postmenopausal women as evidenced by an improvement in endothelium-dependent vasodilatation and a reduction in plasma adhesion molecule levels.
Colacurci
Nicola
N
Department of Gynecology and Obstetrics, IV Internal Medicine, School of Medicine, Second University of Naples, Naples, Italy. nicola.colacurci@unina2.it
Chiàntera
Antonio
A
Fornaro
Felice
F
de Novellis
Vito
V
Manzella
Daniela
D
Arciello
Alessandro
A
Chiàntera
Vito
V
Improta
Lucio
L
Paolisso
Giuseppe
G
D001916:Brachial Artery / Q000033:anatomy & histology / Q000187:drug effects / Q000502:physiology; D004032:Diet; D019040:E-Selectin / Q000097:blood; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology; D005260:Female; D019833:Genistein / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D007529:Isoflavones / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008875:Middle Aged; D019007:P-Selectin / Q000097:blood; D048789:Phytoestrogens / Q000097:blood / Q000494:pharmacology*; D017698:Postmenopause; D011446:Prospective Studies; D013025:Glycine max; D019010:Vascular Cell Adhesion Molecule-1 / Q000097:blood; D014664:Vasodilation / Q000187:drug effects
D019040:E-Selectin; D007529:Isoflavones; D019007:P-Selectin; D048789:Phytoestrogens; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; C004742:daidzein; D019833:Genistein