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A small square of dark chocolate weighing less than one-quarter of an ounce can lower blood pressure in otherwise healthy people with prehypertension or mild hypertension, according to a study published in The Journal of the American Medical Association.

Dark chocolate reduces blood pressure by increasing the production of nitric oxide in the lining of blood vessels. Nitric oxide causes blood vessels to relax and dilate. Only dark chocolate contains cocoa flavanoids, the active ingredient in dark chocolate that stimulates the action of nitric oxide. Milk chocolate and white chocolate have little or no cocoa flavanols and, therefore, have no blood pressure lowering benefit. With only 30 calories in a small square, dark chocolate should not increase your waistline. And, you don’t need a prescription!

If you have high blood pressure or prehypertension, your doctor may recommend a healthy diet, exercise, weight loss, and prescription medications.

The following articles from About.com provide important information about dark chocolate:

• Chocolate as a Health Food? An Affair of the Heart
• Health Benefits of Chocolate