If you have a heart condition, it's important to keep your blood pressure under control to prevent a heart attack. Almost one in three adults has hypertension (high blood pressure), defined as a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher.
While some risk factors for a heart attack cannot be changed – your age, gender, family history and so forth -- other risk factors can be controlled or even eliminated altogether. High blood pressure is one of these.
Now a small study published in the Journal of the American Medical Association (Volume 298, page 49) suggests that a little dark chocolate might help your blood vessels relax. In the study, 44 adults (ages 56–73) with mildly elevated blood pressure levels were randomly assigned to eat a 0.25-oz piece of either dark or white chocolate every day.
Over 18 weeks, those given the dark chocolate saw their systolic and diastolic blood pressures dip slightly -- by an average of two to three points -- while the white chocolate group experienced no change in their blood pressure levels. Eating these small amounts of chocolate did not cause weight gain or harmful increases in blood cholesterol or blood glucose.
Unlike white and milk chocolates, dark chocolate is rich in polyphenols, plant compounds that increase nitric oxide production. Nitric oxide helps blood vessels relax and dilate to facilitate blood flow. In fact, during the study, the formation of nitric oxide appeared to increase in the blood-vessel linings of the dark-chocolate eaters but remained constant in the white-chocolate group.
Take away message: These results are not a chocolate lover’s dream. The daily allotment amounted to 30 calories -- akin to a Hershey’s Kiss rather than a Hershey bar. Remember that overindulgence can lead to weight gain, which can send your blood pressure on the rise.
