ACC: Dark Chocolate Improves Vascular Function

NEW ORLEANS, March 25 -- A cup of cocoa in the morning may improve endothelial function for overweight patients, a small study confirmed, particularly if the dark chocolate powder is mixed with unsweetened water.

In the CDC- and Hershey-sponsored study study, reported at the American College of Cardiology meeting here, daily sugar-free cocoa consumption improved flow mediated dilation 2.4% over a six-week period and an eight-ounce cup of sweetened cocoa improved flow 1.5%. Placebo decreased flow mediated dilation by 0.8%.

Dark chocolate, one of the richest sources of flavinoids, has been shown to improve endothelial function among healthy volunteers, elderly individuals, postmenopausal women, hypertensive patients, and others.

The study affirmed that the benefit extends to otherwise healthy adults with a body mass index 25 to 35 kg/m², said Valentine Yanchou Nijike, M.D., of the Yale Prevention Research Center.

He and colleagues randomized 45 patients to six-week consumption regimens consisting of 11 g of powdered cocoa mixed in eight ounces of water or placebo once a day in a single-blind crossover design with a four-week washout between each.

Patients were 30 to 75 years old, had a waist circumference greater than 88 cm for women or 102 cm for men, had a BMI in the overweight category, and did not smoke.

After 12 hours of fasting, flow mediated dilation of the brachial artery was measured at a morning office visit using high frequency ultrasound before ingestion and two hours after ingestion. This was done at baseline and at the end of each six-week period.

Compared with baseline values, the changes in flow mediated dilation were:

• 2.42.6% for cocoa without sugar (P<0.0001 versus baseline and versus placebo),
• 1.52.7% for cocoa with sugar (P=0.0024 versus baseline and P=0.0021 versus placebo), and
• -0.83.4% for placebo.

Dr. Nijike said the results showed effect modification by sugar but overall indicated cardiovascular risk reduction by cocoa products.

This is good news for preventive care, commented Robert S. Rosenson, M.D., of Northwestern University in Chicago, who moderated a press conference during which the study was discussed.

"The study is relevant for our patients because we so often are told what not to do, and here's something that's good, tastes good, feels good to eat the chocolate and actually you're getting vascular benefits," he said.

However, not all chocolate products may be advantageous because overweight patients have to be concerned about saturated fat and calorie intake, Dr. Rosenson noted.

Because of the small sample size and the specific population examined, "a larger study is warranted before we can make a recommendation of ingestion of cocoa products to determine cardiovascular risk protection," Dr. Nijike concluded.

The study is also needed to see whether the vascular benefit translates to hard clinical outcomes, including heart attacks and strokes, Dr. Rosenson added.