Soya isoflavones in particular have been shown to reduce cardiovascular disease risk as they inhibit the growth of cells that form artery-clogging plaque.
All of the 102 patients in the latest trial had suffered a first or recurrent ischaemic stroke -caused by a blood clot – in the previous six months and had established heart disease.
The patients were split into two groups, with one receiving a 12-week course of isoflavone as an 80mg daily dietary supplement, and the other given a dummy pill or placebo.
The scientists measured the way the brachial artery – the main artery of the arm – dilated in response to an increase in blood flow.
This measurement, the flow-mediated dilatation (FMD), is an indicator of the functioning of the cells that line the inner surfaces of blood vessels – the endothelium – which are implicated in cardiovascular disease.
At the start of the study the prevalence of impaired FMD was similar between the two groups.
But after 12 weeks, the FMD improved significantly in the patients given the isoflavone supplement.