Small amounts of dark chocolate lower blood pressure, study says
Wednesday, July 4, 2007
It's time for chocolate lovers everywhere to celebrate.
German scientists are reporting today that the confection really is good for you. In very, very small doses, anyway.
A study in the Journal of the American Medical Association shows that one bite, or less than a quarter of an ounce, of dark chocolate eaten once a day significantly lowered blood pressure in people who participated in an 18-week clinical trial.
It's the first time researchers have been able to say that a small dose of commercially available chocolate has direct health benefits. Previous chocolate studies have almost always used large doses of chocolate or samples created in labs to pack in extra cocoa flavanols -- the chemical in chocolate thought to relax blood vessels and lower blood pressure.
But the chocolate used in those studies wasn't practical for people to eat every day, because it either didn't taste very good or was heavy on the calories.
If people can get the health benefits of chocolate without the weight gain often associated with it, that's great news, said Seneca Klassen, who could be a little biased as co-owner of Bittersweet Chocolate Cafe in San Francisco.
"Everything should be in moderation, but, yes, clearly there are some health benefits to chocolate," Klassen said. "I have a couple of customers who buy the same bar of chocolate every time and spend a week or two eating it. A little bit can go a long way."
Some nutritionists go so far as to call chocolate a health food. But Bay Area cardiologists -- even those who confess to having a sweet tooth -- aren't quite ready to prescribe chocolate alongside blood pressure medication or daily doses of baby aspirin.
"Sure, you could add a piece of dark chocolate to your prescription. But there are going to be very few people who should rely on that alone," said Dr. Stanley Rockson, chief of consultative cardiology at Stanford University Medical Center.
Still, he said, most of the measures patients have to take to lower their blood pressure aren't fun -- exercising daily and skipping salty and fatty foods, for example -- so "comparable to some of the more draconian measures we make people go through, obviously telling them to eat chocolate is a little easier to comply with."
For more than a decade, scientists have studied the potential health benefits of chocolate, just as they've looked at wine, coffee and other treats that seem sinful to show that they might not be so bad.
The results have been mostly favorable. But when it comes to chocolate, only the dark stuff carries health benefits -- because it allows more flavanols to survive the processing of cocoa and doesn't have nearly as many fat and sugar calories as milk chocolate.
It is thought that chocolate lowers blood pressure when cocoa flavanols spur the release of nitric oxide, which dilates blood vessels and increases blood flow. Chocolate also has been linked to improved learning and memory, also due to improved circulation.
The German study was paid for by the University Hospital of Cologne in Germany, and is one of the first chocolate studies not funded by a chocolate manufacturer. It used a popular candy bar, Ritter Sport semisweet, that is 50 percent cacao. But most researchers say consumers should look for cacao percentages of 65 percent or higher for health benefits.
The study involved just 44 subjects, all of whom were in good health other than having slightly high blood pressure. The volunteers were divided into two groups, one of which ate semisweet chocolate and the other white chocolate -- which doesn't actually have any cocoa in it.
Each person in the semisweet group was asked to eat one square -- 6.3 grams and 30 calories -- just before bedtime every day for 18 weeks. Over that time, systolic blood pressure fell by 3 points and diastolic by 2 points for the semisweet chocolate eaters; blood pressure rates stayed the same for the white chocolate group.
That might not sound like much of a change in blood pressure, but cardiologists said it's a significant drop.
"We don't get a lot better results with most medications, not when we first start them. It's certainly equivalent to other lifestyle and medical approaches to blood pressure," said Dr. Rita Redberg, a UCSF cardiologist. "I'm not going to recommend chocolate, but this could be a good way to continue to lower your blood pressure in addition to already being physically active and eating fruits and vegetables."
Redberg said it's important to note that all of the study subjects were healthy individuals who were not overweight, exercised regularly and reported eating nutritious meals. What worked for them might not work for everyone, especially people who already have high blood pressure.
Plus, and perhaps most important, the people in the study were told to eat no more than the one square of chocolate every day. That, doctors said, might require too much willpower for most people.
Chocolate aficionados said Tuesday they were delighted by the results of the new study, even if they planned to conveniently ignore the part about small doses.
"I love chocolate, so knowing that it's healthy is sort of my excuse to eat it. I know it's not too harmful, anyway," said San Francisco resident Jennifer Lovaas, walking out of Cocoa Bella Chocolates at Westfield San Francisco Centre with a plastic bag of truffles.
Her husband was less enthusiastic. "Whatever good there is probably doesn't outweigh the bad. You can eat an apple and get antioxidants and all that good stuff."
He popped a piece of nutritionally valueless white chocolate in his mouth, and his wife laughed.
"Yeah, he's not even trying to fool himself," she said with a shrug. "We just like chocolate."
What can brown do for you?
The study: Subjects in a German study who ate 0.22 ounces of dark chocolate (actual size, above) every day -- the equivalent of 1 1/2 Hershey's kisses, seven M&Ms or one bite of a chocolate bar -- saw their blood pressure fall 2 to 3 points over 18 weeks.
The reason: Scientists think chocolate helps when flavanols -- a chemical in cocoa -- stimulate the release of nitric oxide in the body, which dilates and relaxes blood vessels and eases blood flow.
The catch: Health benefits are associated only with dark chocolate, not milk chocolate or white chocolate, which don't have enough cocoa flavanols.
What's in your chocolate?
Chocolate is made from cacao nibs, the part of the cacao bean that is fermented, dried, roasted and ground. Various other ingredients are added to make chocolate bars, truffles and other confections. But there's a whole world of terminology chocoholics use to describe their favorite food:
Chocolate liquor. This liquid results when the cacao nib is ground. It's made of cocoa solids (cocoa powder) and cocoa butter and, despite its name, is nonalcoholic.
Cocoa butter: The fat from the cacao bean. Extra cocoa butter may also be added to the chocolate.
Cocoa powder: The solids that remain once the cocoa butter has been pressed out of the chocolate liquor.
Flavors and additives: Sugar, vanilla and soy lecithin (an emulsifier) are the other ingredients added to make chocolate palatable. Many commercial chocolates also contain other types of fat (such as vegetable oil), sweeteners, flavors or ingredients.
Cacao percentage or content: The amount of chocolate from the cacao nib, plus naturally occurring or added cocoa butter. This is a measurement by weight and does not include sugar, vanilla or other additives. Chocolate with a higher percentage of cacao, to a point, is often considered to be higher quality, or more chocolate-y. Still, experts don't necessarily agree on the optimal percentage, although there are requirements for certain types of chocolate.
Unsweetened chocolate: Chocolate liquor that has been molded into blocks and is used for baking.
White chocolate: Must contain at least 20 percent cocoa butter, but no cocoa powder or chocolate liquor.
Milk chocolate: Must contain at least 10 percent chocolate liquor and 12 percent milk solids.
Semisweet or bittersweet chocolate: Must contain at least 35 percent chocolate liquor and less than 12 percent milk solids. Bittersweet often contains 50 percent chocolate liquor.
Dark chocolate: Definitions vary, but dark chocolate generally contains 45 to 85 percent cacao. Also can be called semisweet or bittersweet.
Couverture: Fine chocolate that contains a minimum of 32 percent cocoa butter. This is used by professional confectioners to get a thin, glossy chocolate coating.
Single-varietal chocolate: The latest trend in chocolate, similar to wine, where the chocolate comes from cacao beans from one specific growing area with unique characteristics.
Artisan chocolate: Uses couverture chocolate and emphasizes the source and quality of ingredients, such as organic or fair trade.
Source: Guittard, Ghirardelli
E-mail Erin Allday at firstname.lastname@example.org.
This article appeared on page A - 1 of the San Francisco Chronicle