Stroke patients may benefit from isoflavone-rich diet
A new study may offer stroke victims a ray of hope. Researchers say a dietary supplement containing isoflavone can give a boost to the functioning of patients' arteries. Sources say this latest work is probably the first randomised, controlled trial assessing how isoflavone supplement affects the brachial artery. The findings were recently published in the European Heart Journal. The researchers, led by Hung-Fat Tse, Professor of Cardiology and academic chief of the Cardiology Unit in the Department of Medicine, Queen Mary Hospital, the University of Hong Kong, discovered that patients who were given daily doses of an isoflavone supplement (80mg) over a 12-week period showed major improvements in flow-mediated dilation (FMD) in the brachial artery (the main artery in the arm). FMD is a measure of endothelial dysfunction used to assess cardiovascular risk, experts say. Brachial FMD is an indicator of how cells lining the inner surfaces of blood vessels perform (i.e. vascular endothelium). According to the research team, endothelial dysfunction could be the source triggering cardiovascular disease. In this study, the researchers found that the isoflavone supplement helped lessen vascular endothelial dysfunction in patients who had suffered an ischaemic stroke. The researchers carried out a double-blind, placebo-controlled trial. The isoflavone supplement was given to 50 patients, while the placebo was given to 52 patients. FMD, said the researchers, was measured via ultrasound to record the functioning of the brachial artery as the blood flow returned to normal after pneumatic tourniquets placed on the forearms of patients were inflated and then released. The percentage change in the brachial artery diameter between the baseline (i.e. normal size) and one minute after the deflation of the tourniquet determined the FMD, they said. The research team recorded an FMD impairment of less than 3.7% in 80% of the patients assessed at the start of the study, but the 12-week trial showed a 1% improvement in the isoflavone group compared to the control group. 'The findings may have important implications for the use of isoflavone for secondary prevention in patients with cardiovascular disease, on top of conventional treatments,' the researchers wrote in their paper. 'The treatment effect of isoflavone in our study was comparable with lifestyle changes with endurance training or pharmacological interventions with statin therapy.' For his part, Professor Tse said: 'Although the absolute increase in brachial diameter (1%) is small, the relative increase actually amounted to about 50% because the mean average FMD in these stroke patients was about 2%. In fact, in patients with severe endothelial dysfunction, there might not be dilatation of brachial diameter at all.' The researcher also pointed out that patients with a lower initial FMD and who received the isoflavone supplement responded with a larger absolute increase in FMD versus patients who had a better baseline FMD to begin with. 'These findings suggest that isoflavone reverses endothelial dysfunction in this group of patients with cardiovascular disease,' he said. 'This has important clinical implications, as the benefit of the treatment is conferred to the group of patients with the highest risks for cardiovascular events, and this effect persists, even at this rather late stage of the cardiovascular continuum.' Researchers have yet to fully understand the mechanisms by which isoflavone triggers these changes in FMD. While it is still unclear how the isoflavone supplements could be used clinically, this study showed that cardiovascular risk could drop in stroke patients who suffered ischaemic strokes if they followed diets with higher isoflavone contents. 'A balanced diet is still the top priority in promoting health,' Professor Tse said.