Asians suffer less frequently from cardiovascular diseases than Caucasians. The isoflavones are therefore thought to play an important role for the reduction of the cardiovascular risk (Crouse, III et al. 1999).
Mechanisms of isoflavones potentially contributing to cardiovascular prevention are:
- Antioxidative and anti-inflammatory effects;
- Improvement of microcirculation; and an
- Improvement of the endothelial function.
Clinically, a distinct improvement of microcirculation was found in a six-week placebo-controlled clinical trial in postmenopausal women (Wroblewsi Lissin et al. 2004).
Vasodilatation as a reaction to isoflavone exposure was clearly demonstrated in model trials in healthy volunteers. It was apparently related to an activation of the endothelial nitrogen oxide synthetase (eNOS) – a system responsible for the finetuning of blood pressure and microcirculation (Chin-Dusting et al. 2004).
The eNOS system is itself activated via estrogenic mechanisms by transactivation of both, ER-α and ER-β. In postmenopause the decreasing estrogen levels lead to an insufficient activation of eNOS, which may contribute to the increasing rate of cardiovascular disorders with increasing age. This may also explain why cardiovascular disorders are less frequent in Asian countries with a high dietary intake of isoflavones, and thus with a class of natural compounds which may positively influence the eNOS system by activation of ER-β.
References
Chin-Dusting, J. P., Boak, L., Husband, A., and Nestel, P. J. (2004). The isoflavone metabolite dehydroequol produces vasodilatation in human resistance arteries via a nitric oxide-dependent mechanism. Atherosclerosis 176 (1): 45-48.
Crouse, J. R., III, Morgan, T., Terry, J. G., Ellis, J., Vitolins, M., and Burke, G. L. (1999). A randomized trial comparing the effect of casein with that of soy protein containing varying amounts of isoflavones on plasma concentrations of lipids and lipoproteins. Arch. Intern. Med. 159 (17): 2070-2076.
Wroblewsi Lissin, L., Oka, R., Lakshmi, S., and Cooke, J. P. (2004). Isoflavones improve vascular reactivity in post-menopausal women with hypercholesterolemia. Vasc. Med. 9 (1): 26-30.
Clinical effects 