Dark Chocolate Lowers Blood Pressure

People with high blood pressure can lower it by consuming dark chocolate, according to a report in the Journal of the American Medical Association (2003;290:1029–30). While this report adds to a growing body of evidence indicating that chocolate consumption can produce certain positive effects, it would be premature to conclude that the benefits of chocolate outweigh its adverse effects.

In the new study, a group of individuals with systolic hypertension (i.e., the higher of the two blood pressure numbers was above normal) were randomly assigned to consume 100 grams of dark chocolate each day for two weeks or a similar amount of white chocolate. Each participant then consumed the other type of chocolate for another two weeks. The two types of chocolate are different in that dark chocolate contains a relatively large amount of a substance called polyphenols, which have been shown to decrease blood pressure, whereas white chocolate contains no polyphenols. Compared with white chocolate, dark chocolate significantly reduced both systolic and diastolic blood pressure, by 5.1 and 1.8 mm Hg, respectively.

An improvement in high blood pressure would be expected to reduce the risk of heart disease. In addition, polyphenols from dark chocolate have antioxidant activity, which also might be beneficial for the heart. However, the mood-altering and addictive nature of chocolate is widely recognized, and over-consumption of chocolate appears to be a problem for many people, so before running out to buy a box of your favorite candy bar, there are several factors to consider. First, the amount of dark chocolate ingested by participants in the new study provided 480 calories per day, an amount that would likely contribute to the development of obesity if continued for a long period of time. In addition, chocolate contains several different stimulants, including caffeine and an amphetamine-like chemical called phenylethylamine. Moreover, a substance named anandamide, which binds to the same receptor sites on brain cells as the active ingredient in marijuana, has also been identified in chocolate.

Therefore, despite its potentially beneficial effects, the available evidence does not suggest that eating large amounts of chocolate is good for one's health. Fortunately, it is not necessary to consume chocolate in order to obtain polyphenols; these compounds are also present in a wide array of fruits and vegetables, as well as in tea and red wine.

Those seeking the positive effects of chocolate should remember that milk chocolate probably does not provide the same benefits as dark chocolate. The addition of milk to dark chocolate causes chemical bonds to form between milk proteins and polyphenols, thereby inhibiting the absorption of polyphenols into the body.

Alan R. Gaby, MD, an expert in nutritional therapies, testified to the White House Commission on CAM upon request in December 2001. Dr. Gaby served as a member of the Ad-Hoc Advisory Panel of the National Institutes of Health Office of Alternative Medicine. He is the author of Preventing and Reversing Osteoporosis (Prima, 1994), and co-author of The Natural Pharmacy, 2nd Edition (Healthnotes, Prima, 1999), the A–Z Guide to Drug-Herb-Vitamin Interactions (Healthnotes, Prima, 1999), Clinical Essentials Volume 1 and 2 (Healthnotes, 2000), and The Patient’s Book of Natural Healing (Prima, 1999). A former professor at Bastyr University of Natural Health Sciences, in Kenmore, WA, where he served as the Endowed Professor of Nutrition, Dr. Gaby is the Chief Medical Editor for Healthnotes, Inc.

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