By Natasha Persaud
Everything’s better with chocolate—including blood pressure, it seems. A review of 20 small studies, published in The Cochrane Library, confirms a modest dip in blood pressure after eating flavanol-rich dark chocolate or cocoa drinks. Along with a low-sodium diet and regular exercise, it may be a delicious way to stay heart healthy.
How big was the decline in blood pressure?
Systolic blood pressure, the top number in a blood pressure reading (e.g.,140/90 mm Hg), decreased by 2.8 points on average over the short term. Diastolic blood pressure, the bottom number in a reading, declined by 2.2 points.
It’s a small drop in blood pressure, but meaningful. The risk of heart disease—the number one killer in the U.S.—declines with even modest reductions in elevated blood pressure.
Who benefited the most?
The 20 studies involved mainly healthy adults, including some with hypertension (i.e., 140/90 mm Hg or higher). People younger than age 50 had a greater response to cocoa, possibly because their arteries were less stiff and could open wider, easing blood flow.
What are cocoa flavanols?
Researchers have been eagerly studying flavanols, compounds found in plants, for their purported health benefits. Natural cocoa from cacao beans is rich in flavanols, particularly epicatechin, catechin and procyanidins. All of the studies in this review provided cocoa drinks and dark chocolates with high concentrations of flavanols.
How might flavanols lower blood pressure?
High flavanol foods may increase the production of nitric oxide, which widens arteries and lowers blood pressure. Flavanols may also improve insulin sensitivity, have an antioxidant effect, or lower ACE (enzyme) activity—all of which may contribute to lower blood pressure.
Are all chocolates and cocoa products created equal?
No, and this is an important point. The amount of flavanols in commercially prepared chocolates and cocoas varies tremendously due to processing for taste, color and texture. Heavy dutching, the alkalizing of chocolate to pH 7-8, can reduce flavanol content to less than 10 mg per 100 grams. Compare that to the 500 to 750 mg of flavanols consumed daily in half of the studies.
Chocolate manufacturers are aware of the possible health benefits of flavanols, and some have been working to increase the flavanol content of their products.
So, can I eat or drink chocolate every day? (wishful thinking!)
Before you overindulge, stay tuned for future research. Longer studies need to be conducted to see if blood pressure stays lowered with a daily dose of flavanol-rich dark chocolate or cocoa. But if you are a chocolate lover, lower blood pressure is a nice plus for enjoying a tasty cocoa treat.
Look for high flavanol, low sugar varieties of cocoa products and chocolates, which the researchers suggest provide the greatest benefit. Keep an eye on the fat content and portion size too. Too much fat and calories can lead to weight gain which, in turn, raises blood pressure.
Generally, dark chocolates have more cocoa than milk chocolates, and therefore more flavanols. (White chocolate has none.)
The percentage of cocoa in a product won’t tell you how much flavanols it contains, though. A 70 percent cocoa chocolate bar from one company, for example, might contain a different amount of flavanols than a 70 percent bar from another company.
What other foods contain flavanols?
Beans, apricots, blackberries, apples and tea leaves also contain flavanols, but in smaller amounts.
I don’t have high blood pressure. Why should I care about this research?
Chocolate isn't a cure. Still, a lot of people need to take lifestyle measures to prevent or reduce hypertension, especially those with borderline blood pressure, such as 130/80 mm Hg. A heart healthy diet and regular exercise is key.
As many as 1 in 3 adults in the U.S. eventually develops high blood pressure and needs to be treated. Since hypertension usually causes no symptoms and increases with age, have your blood pressure measured periodically at the doctor’s office.
Ried, Sullivan, Fakler, Frank, Stocks. Effect of Cocoa on Blood Pressure (Review). The Cochrane Library 2012, Issue 8.