July 3, 2007 -- Chocolate-lovers can take heart in the candy aisles, as it seems just a little bit of the dark, sweet stuff can help lower blood pressure.
A new study published today in the Journal of the American Medical Association reports that a small dose of dark chocolate lowers blood pressure without causing weight gain.
"We found that it's good to eat small amounts of dark chocolate every day on a regular basis," says lead study author Dr. Dirk Taubert, professor at the University Hospital of Cologne, Germany.
Taubert and his research team doled out daily "doses" of either white chocolate or dark chocolate to 44 adults with slightly high blood pressure, between 130/85 and 160/100. Normal blood pressure is commonly thought to be around 120/80 -- or a systolic of 120 and a diastolic of 80.
The amount -- 6.3 grams -- was equal to the size of one Hershey's kiss, or about half a square in a chocolate bar, and contained about 30 calories.
The participants had their blood pressure monitored for 18 weeks.
The group that ate the dark chocolate reduced its systolic (top number) blood pressure by 2.9, and its diastolic (bottom number) blood pressure by 1.9. The participants who ate the white chocolate saw no such benefits.
Taubert says, "At first glance, a decrease of two or three points may be very small, but if everyone would experience a reduction of blood pressure in this range, you would have a reduction of coronary artery disease mortality of 5 percent, and this is clinically relevant."
Bitter on the Tongue, Sweet for the Heart
Scientists have known for some time that cocoa polyphenols, the substance that gives dark chocolate its characteristic bitter taste, can affect blood pressure. But this was the first time that a small dose was studied.
"The problem was we previously only assessed the impact in large doses -- one bar per day -- over a short time," says Taubert. "Therefore, we conducted a more relevant study with very low amounts of chocolate -- one square per day -- and over a longer term."
The researchers say the polyphenols increase nitric oxide, a naturally occurring substance in the body that relaxes blood vessels, making it easier for blood to pump through arteries and veins.
The Dose Is the Poison
Experts agree that the findings are exciting, but some wonder how likely people are to eat only a small bit of chocolate.
"Our society, media and our business industries do not promote moderation," says Dr. Stephen Cook, assistant professor of pediatrics at the University of Rochester Medical Center.
"So, small findings like this end up getting misunderstood by the masses and seem to give them a green light for eating a pound of dark chocolate per day."
The study's authors also maintain that their findings show that dark chocolate can be part of a preventive health strategy in small amounts but should not replace blood pressure medications.
"We need to determine what is a dose of dark chocolate that is reasonable, satisfying and beneficial -- without adverse effects on weight control," says Dr. David Katz, director of the prevention research center at the Yale School of Medicine.
"The blood pressure reduction seen here is significant, particularly so given the nature of the intervention -- something that is easily accessible to all at low cost, and is appetizing in the bargain."
Other experts say this is an opportunity to stress the importance of maintaining a diet that is varied, with a lot of fruits and vegetables.
"This provides an excellent chance to say, 'you can enjoy what you love if you learn to eat the right amount,'" says Connie Diekman, president of the American Dietetic Association.
The type of dark chocolate is important as well, diet experts say. In the study, the scientists used chocolate with at least 30 mg of polyphenols, which translates into a fairly bitter chocolate mix.
"We're a long way from dark chocolate becoming a deductible expense, but for people who enjoy chocolate, I have been telling them to have the darkest chocolate they can find, at least 70 percent cocoa is dark enough and still quite edible," says Keith Ayoob, associate professor of pediatrics at Albert Einstein College of Medicine.
"If people want only white or milk chocolate, fine, but no health benefits there -- it's just candy."
Polyphenols can also be found in certain types of tea, apples and red wine.
As for lead author Taubert, he says he eats chocolate for a different reason.
"Yes, I like chocolate. I eat it not for health reasons but only because it's delicious."