Flavonoid rich dark chocolate (45 g per day) significantly improved coronary flow velocity reserve (CFVR), this means that the researchers used Doppler echocardiography to assess the ability of the coronary arteries to dilate and allow more blood flow in response to dark chocolate. Dark chocolate improves coronary circulation in healthy adults. The other group in this randomized single blind study used 35 g of non-flavonoid white chocolate and their CFVR did not significantly improve.
They studied 39 healthy men who during the trial were not allowed to use other flavonoid rich food such as tea and wine. The 39 adults used the chocolate only during two weeks. The 45 g of dark chocolate contained 550 mg/day flavonoiden and equaled 200 kcal. The white chocolate did not contain flavonoiden and the 35 g equals 140 kcal. That’s the only problem chocolate is a calorie rich nutrient.
The two groups didn’t differ in blood pressures, lipid profile, blood sugar, and measures of oxidative stress either before or after the two weeks of chocolate intake. The authors suggest that flavinoids increase nitric oxyde but based on this research other possible expalnations for it’s working mechanism can not be excluded. For more information about the possible ways chocolate protects the cardiovascular system read: Chocolate and Cardiovascular Health and How does chocolate protect the heart.
The only limitations are that they studied the short term effects of dark chocolate and only in healthy men. It is possible that effects would be more pronounced when studied over a longer period of time and it’s also possible that the effects would larger in patients with cardiovascular disease.
Shiina, Y., Funabashi, N., Lee, K., Murayama, T., Nakamura, K., Wakatsuki, Y., Daimon, M., & Komuro, I. (2009). Acute effect of oral flavonoid-rich dark chocolate intake on coronary circulation, as compared with non-flavonoid white chocolate, by transthoracic Doppler echocardiography in healthy adults International Journal of Cardiology, 131 (3), 424-429 DOI: 10.1016/j.ijcard.2007.07.131