March 30, 2010 -- Willy Wonka may have been on the right track -- chocolate may be a sweet way to control blood pressure and thus protect the heart, according to a report from German researchers.
But before you stock up on chocolate bunnies, consider this: the chocolate benefit was greatest among people who consumed about 7.5 grams of chocolate daily. That works out to about a quarter of an ounce, which is barely a nibble from a typical Hershey bar, which weighs in at 1.55 ounces.
Nonetheless consuming 7.5 grams of chocolate daily resulted in a significantly lower blood pressure than consuming just a sprinkle of it daily, according to Brian Buijsse of the German Institute of Human Nutrition in Nuthetal, Germany, and colleagues.
They reported their findings online in the European Heart Journal.
"It's a little early to make recommendations [about chocolate consumption]," Buijsse told MedPage Today, cautioning that more studies are needed. "But a future recommendation could be that if people eat a small amount of chocolate, they can replace it for something else, maybe leaving out a snack or another sweet."
Chocolate has been studied extensively over the past decade for its potential benefits on the heart and vasculature. Just last month, a study found that chocolate reduces the risk of stroke.
For the present study, the researchers studied almost 20,000 patients who were enrolled in a large European cancer study. All the patients were age 35 to 65 and the study was conducted from 1994 to 2006.
Dietary habits and health outcomes were assessed via questionnaire, and the cohort was followed for a mean of eight years.
The researchers also asked a subset of 1,568 patients to recall their chocolate intake over a 24-hour period to determine which type of chocolate they ate -- white, milk, or dark.
On average blood pressure was about one point lower for both systolic -- the first number in blood pressure -- and diastolic, they said.
During follow-up, there were a total of 166 heart attacks and 136 strokes.
Those who ate the most chocolate had a 39 percent lower risk of the combined outcome of heart attack and stroke.
"The association was stronger for stroke," Buijsse said. "That's logical because high blood pressure is a stronger risk factor for stroke than for heart disease."
Baseline blood pressure explained just 12 percent of this lower risk, the researchers added.
Buijsse said that a "healthy user" effect is unlikely in this study because consumption of fruits, vegetables, and dairy was inversely related to chocolate consumption.
"Despite lower intakes of fruits and vegetables, they still had a lower risk of heart disease," he said.
The researchers said dark chocolate might hold more benefit over all other types of chocolate, because it is particularly high in flavonols. These compounds may improve endothelial function by improving the elasticity of blood vessels, Buijsse said.
Yet he cautioned that people shouldn't increase their overall caloric intake by adding chocolate to their diet.
"Chocolate is very calorie rich," Buijsse said. "Studies show that if people eat 25 grams a day, they will gain weight. Weight gain will lead to overweight and obesity, which has detrimental effects on blood pressure, heart disease, and even cancer, so we don't want that."
But if chocolate can replace other snacks in the diet, that should be beneficial, he added.
The researchers said they need more randomized controlled trials before they can make definite recommendations about chocolate intake.
The study was limited because chocolate consumption was estimated by only one item in the questionnaire, and thus may have been underestimated. Also, dietary intake, risk factors, and blood pressure were assessed at baseline only, so the study assumes these variables remained stable over time. Finally, it was limited by self-reported data.