Does Chocolate Really Help Your Heart?

The Danish Diet, Cancer and Health Study has turned up an interesting observation: people who eat chocolate are less likely to develop atrial fibrillation, a heart rhythm abnormality that affects between 2 and 6 million American. Atrial fibrillation, or Afib, is associated with a greater chance of stroke, cognitive decline and heart failure. But does chocolate really help? It might be too much to expect.

What Did the Danish Study Show?

The Danish study included 55,502 men and women who answered detailed questionnaires about their food consumption at the beginning of nearly 14 years of follow-up. They could report various frequencies of chocolate consumption, from “never” to “four or five times a day.” During the study, participants experienced 3,346 cases of atrial fibrillation.

Those who ate an ounce of chocolate at least once a month were 10 percent less likely to develop Afib. Those who consumed chocolate every week had a 17 percent lower risk, while those who had two to six servings a week lowered their risk by about 20 percent. There was no benefit to eating more than six servings weekly.

How Much Is a Serving?

The scientists determined that a serving was about one ounce, roughly equivalent to 30 grams. Some large chocolate bars are 2.5 or 3 ounces, while a Hershey’s bar, for example, is 1.55 ounces. The volunteers were not asked whether they were eating dark or milk chocolate, but dark chocolate is more popular in Denmark. Dark chocolate has more cocoa flavonoids in it.

Could Chocolate Really Help Prevent Afib?

Epidemiological studies like this one cannot establish cause and effect. Other studies have shown that cocoa flavonoids in chocolate relax blood vessels and lower blood pressure, keep platelets from clotting inappropriately and reduce the risk of dementia.

The investigators on the Danish Diet, Cancer and Health Study point out that European chocolate is higher in cocoa than many popular American chocolates. So while you can’t necessarily count on chocolate to help your heart, you needn’t feel guilty about munching a small amount of dark chocolate at least once a week. You might even be doing your heart good.

Mostofsky et al, Heart, May 23, 2017

From a Reader:

Years ago, we heard from a reader who got very good results eating chocolate to lower blood pressure:

Q. I’ve got a comment about the dark chocolate controversy on whether it is irresponsible to recommend chocolate for health benefits.

I started eating Hershey’s dark chocolate when it was on sale a few weeks ago. I enjoy about five of the little squares twice a day. Both my systolic and diastolic blood pressure numbers went down about 15 or 20 points each.

A. Could chocolate really help lower blood pressure? It will never substitute for medicine, but some data support your experience. Studies have demonstrated modest of benefits of cocoa and dark chocolate in lowering blood pressure (Grassi et al, Hypertension, Aug., 2005; Archives of Internal Medicine, Feb. 27, 2006).

Your reaction to chocolate is much greater than average. A carefully conducted meta-analysis of 35 studies found that blood pressure dropped about 2 points, on average, when people consumed cocoa flavanols (Ried et al, Cochrane Database of Systematic Reviews, April 25, 2017). Studies of chocolate and blood pressure have used doses ranging from 10 g (the size of one Ghirardelli chocolate square) to 100 g (the size of a Ritter Sport bar).