A new study by cardiologists and researchers at UCSF found that high concentrations of cocoa flavanols—natural compounds found in apples, grapes, tea, cocoa and cherries—decrease blood pressure and improve the health of blood vessels in patients with heart disease. The UCSF team showed for the first time that increasing angiogenesis-promoting cells in the blood is one of the possible mechanisms of flavanol’s heart benefit. Findings are published in the July 13, 2010 issue of the Journal of the American College of Cardiology.

The study included 16 coronary artery disease patients aged 64 (± 3 years) who were given a high-flavanol cocoa drink (375 mg of flavanols) twice a day over 30 days, and then a nutrient-matched low-flavanol cocoa drink (9 mg flavanols) twice a day over 30 days. The participants continued taking all regular medications for their underlying heart disease during the study, including cholesterol-lowering medications.

Tests showed a 47% improvement in vasodilation, or widening rather than constriction, of the brachial artery in the high-flavanol time period compared to the low-flavanol period. There was also a two-fold increase in angiogenesis-stimulating cells in the blood, known as endothelial progenitor cells, that was similar to that achieved by therapy with statins and with lifestyle changes such as exercise and smoking cessation.

“This is exciting data,” said cardiologist Yerem Yeghiazarians, M.D., senior author, associate professor of medicine, and researcher in the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UCSF. “Our findings demonstrate that a further increase in endothelial function and improvement in blood pressure can be achieved by complementing standard treatment with a flavanol-rich diet.

Notably, the therapy did not influence fasting glucose levels of study participants. (Fasting glucose is the standard for measuring an individual’s blood sugar level to diagnose conditions such as diabetes and heart disease). Long-term trials examining the effects of high-flavanol diets on cardiovascular health and function are warranted, but these early findings help us understand how these compounds impact the function of damaged blood vessels.