The latest news about chocolate - that it makes blood vessels more flexible - adds to accumulating evidence that chocolate offers a number of health benefits and may be good for the heart. Earlier findings had shown that chocolate contains polyphenols, the same kinds of antioxidants found in red wine and green tea; stearic acid, a type of fat that doesn't raise cholesterol levels; and flavonoids, which reduce the stickiness of platelets, inhibiting blood clotting and reducing the danger of coronary artery blockages.
In the most recent study, researchers at Athens Medical School in Greece recruited 17 healthy young volunteers who agreed to eat a 3.5-ounce bar of dark chocolate and then undergo ultrasound tests to see how the chocolate affected the functioning of endothelial cells in blood-vessel walls. Normally, these cells control the stiffness of blood vessels by secreting substances that regulate flexibility.
The researchers found that on the days the volunteers ate dark chocolate (as opposed to those who ate fake chocolate), endothelial function was improved for about three hours. These are interesting findings, but we don't yet know what they mean in terms of preventing cardiovascular disease, heart attacks, or deaths. This study doesn't tell us whether eating dark chocolate on a regular basis would reduce the risk of heart disease.
We do know, however, that eating too much chocolate can lead to weight gain, which might cancel out any beneficial effects that chocolate confers. So the good news about chocolate isn't a license to overindulge. I enjoy high-quality dark chocolate from France, Belgium and Venezuela. It is so richly delicious that a single piece is a satisfying snack or after-dinner treat. Limit yourself to an ounce several times a week. If you can't find good imported chocolate, look for a domestic brand that contains at least 70 percent cocoa.
Andrew Weil, M.D.