Dark chocolate can boost coronary blood flow reserve

Researchers in Japan have found that dark chocolate can have a positive impact on coronarycirculation.

A team at Chiba University, Chiba, Japan, used transthoracic Doppler echocardiography (TTDE) toassess coronary flow velocity reserve (CFVR) following two weeks of high-flavonoid dark chocolateintake. CFVR is an indicator of ability of coronary arteries to dilate and allow greater blood flowas needed.

"Flavonoid-rich dark chocolate had acute effects in improving coronary circulation in healthyadults as compared to nonflavonoid white chocolate," researchers said at the American HeartAssociation Scientific Sessions in Orlando, Nov. 3-6, 2007. "The positive effects were independent ofchanges in oxidative stress parameters, heart rate and lipid profiles."

The single-blind study was conducted with 39 healthy adults between ages 23 and 40 years.Participants were randomized to eat either daily consumption of dark chocolate with 550 mg of cacaopolyphenol (200 kcal) or white chocolate containing no flavonoids (140 kcal) in addition to theirregular daily diet.

CFVR was measured at baseline and again two weeks later at the study's end. Researchers also measuredserum asymmetric dimethylarginine (ADMA), 8-isoprostanes and malondialdehyde-modified low densitylipoproteins (MDA-LDL) as markers of oxidative stress as well as heart rate and blood lipid profiles.The result, researchers noted, was a significant increase in CFVR from 3.38 at baseline to 4.28(PP=0.49) at the end of thestudy.

Multiple regression analysis showed that dark chocolate was associated with the increase in CFVR butthat white chocolate, ADMA, MDA-LDL, triglycerides and heart rate did not have a significant effect(P