Isolated soy protein improves endothelial function in postmenopausal hypercholesterolemic women

Abstract

Background: Postmenopausia and hypercholesterolemia are related to endothelial dysfunction, a pathogenic event in atherosclerosis. Soy protein reduces plasma cholesterol, but there is scanty information about its effect on endothelial function. Objective: To evaluate the effect of isolated soy protein compared to caseinate on plasma lipoproteins and endothelial function in postmenopausal hypercholesterolemic women. Design: Randomized, double-blind, cross-over trial. Setting: Outpatient clinic of the Catholic University of Chile. Subjects: Eighteen healthy, postmenopausal women with hypercholesterolemia were recruited, included and completed the protocol. Interventions: During the trial, all patients followed a low fat/low cholesterol diet and were randomly assigned to receive isolated soy protein or matching caseinate for 4 weeks, and then the alternative treatment until week 8. At pre-study and at the end of the first and second period, plasma lipoprotein levels and endothelial function (flow-mediated dilatation (FMD) of the brachial artery) were evaluated. Results: Plasma total and low density lipoprotein (LDL)-cholesterol concentration were significantly lower with the low fat/low cholesterol diet compared to pre-study, either with caseinate or soy protein. No significant differences in plasma lipid concentration between caseinate or soy protein interventions were observed. FMD did not change with the caseinate. In contrast, when soy protein was administered, FMD was significantly higher compared to pre-study (9.471.8% vs 5.371.2%; Po0.05) and compared to caseinate intervention (9.471.8% vs 4.971.5%; Po0.033). Conclusions: These results suggest that in postmenopausal hypercholesterolemic women, soy protein improves endothelial function, regardless of changes in plasma lipoproteins. Sponsorship: Pontificia Universidad Cató lica (DIPUC99/09E), Protein Technology International and Gynopharm Laboratory (Recalcine Group).

Diet and Endothelial Function

“…Consistently, we recently demonstrated that supplementation with soy protein to postmenopausal hypercholesterolemic women improves flow-mediated dilation, regardless of changes in plasma lipoproteins. We hypothesized that isoflavones are responsible for this beneficial effect (55).…”

Evidence for a protective effect of polyphenols-containing foods on cardiovascular health: an update for clinicians

“…Owing to the oestrogen-like nature of isoflavones, the subjects involved in most of these studies were menopausal women, known to have FMD values ranging from 'severely reduced' to 'normal' [Corretti et al 2002]. As underlined by Teragawa and colleagues [Teragawa et al 2008], an improved endothelial function in response to isoflavones or isoflavones-rich products intake was only found in subjects with a baseline reduced FMD [Cuevas et al 2003]. Furthermore, in a randomized, double-blind, placebo-controlled trial, Chan and colleagues demonstrated that oral isoflavone supplements (80 mg/day), taken over 12 weeks, moderately but significantly restored FMD levels in patients with prior ischaemic stroke [Chan et al 2008].…”

Genistein activates endothelial nitric oxide synthase in broiler pulmonary arterial endothelial cells by an Akt-dependent mechanism

“…Among phytoestrogens, genistein and daidzein, two major isoflavones in soybeans are the well-studied due to their wide distribution. In vitro and in vivo studies indicated that genistein supplementation has abilities to improve endothelial dysfunction in postmenopausal women, ovariectomized or chronically hypoxic rats (Squadrito et al, 2000;Karamsetty et al, 2001;Catania et al, 2002;Cuevas et al, 2003). Further The rapid activation of eNOS by genistein is through a non-genomic mechanism.…”