Soya isoflavone-enriched cereal bars affect markers of endothelial function in postmenopausal women
2006
Hallund, J. | Bugel, S. | Tholstrup, T. | Ferrari, M. | Talbot, D. | Hall, W.L. | Reimann, M. | Williams, C.M. | Wiinberg, N.
Soya isoflavones are thought to be cardioprotective due to their structural similarity to oestrogen. In order to investigate the effect of soya isoflavones on markers of endothelial function we conducted a randomised, double-blind, placebo-controlled, cross-over study with thirty healthy postmenopausal women. The women consumed cereal bars, with or without soya isoflavones (50 mg/d), for 8 weeks, separated by an 8-week washout period. Systemic arterial complince (SAC), isobaric arterial compliance (IAC), flow-mediated endothelium-dependent vasodilation (FMD) and nitroglycerine-mediated endothelium-independent vasodilation (NMD) were measured at the beginning of the study and after each intervention period. Blood pressure (BP) and plasma concentrations of nitrite and nitrate (NOx) and endothelin-1 (ET-1) were measured at the beginning and end of each intervention period. NMD was 13.4 (SEM 2.0) % at baseline and 15.5 (SEM 1.1) % after isoflavone treatment compared with 12.4 (SEM 1.0) % after placebo treatment (P=0.03). NOx increased from 27.7 (SEM 2.7) to 31.1 (SEM 3.2) micromolar after isoflavones treatment compared with 25.4 (SEM 1.5) to 20.4 (SEM 1.1) micromolar after placebo treatment (P=0.003) and a significant increase in the NOx:ET-1 ratio (P=0.005) was observed after the isoflavone treatment compared with placebo. A significant difference in SAC after the isoflavone and placebo treatment was observed (P=0.04). No significant difference was found in FMD, IAC, BP and ET-1. In conclusion, 8 weeks' consumption of cereals bars enriched with 50 mg soya isoflavones/d increased plasma NOx concentrations and improved endothelium-independent vasodilation in healthy postmenopausal women.
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