Condition - Soy reduces heart disease risk
Previous trials have shown that soy can help to reduce cholesterol levels but more recent evidence suggests that soy isoflavones could also reduce other cardiovascular disease (CVD) risk factors, such as blood pressure and endothelial dysfunction.
Endothelial dysfunction can be broadly defined as an imbalance between blood vessel dilating and constricting substances, produced by (or acting on) blood vessel lining cells. It signifies the early stages of heart disease and is a predictive marker for long-term CVD and mortality.
A new meta-analysis, published in the journal Nutrition, Metabolism & Cardiovascular Diseases, has analysed 17 studies on the effect of soy isoflavones on endothelial function. “Cumulative evidence from the randomised, controlled trials included in this meta-analysis suggests that exposure to soy isoflavones can modestly, but significantly, improve endothelial function,” reported the researchers.
The meta-analysis found the overall change in endothelial function for isoflavone-containing soy product interventions to be 1.15%. When the results of trials on different types of soy were separated, isolated isoflavones were found to improve endothelial function by 1.98%, compared with 0.72% improvements seen with soy protein.
Researchers stated the key mechanism behind endothelial dysfunction involves the impaired release of nitric oxide (NO), causing blood vessels to constrict. Increased availability of isoflavones is suggested to increase NO production.
Beavers et al. (2010) Exposure to isoflavone–containing soy products and endothelial function: A Bayesian meta–analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. [Epub ahead of print]