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Does Chocolate Really Help Your Heart?

A Danish study found that people who eat chocolate are less likely to have atrial fibrillation. Does chocolate really help prevent Afib?

Most people think of chocolate as a sinful indulgence. We may be prepared to pay the price of the extra calories, but we don’t expect it to have any health benefits. Might we be wrong, though? Could chocolate really help your health in a variety of ways?

A Bit of History:

Thousands of years ago people in ancient Mesoamerican civilizations prized cacao, the plant that gives us chocolate. Not only did they use its seeds as money, they considered it a health-promoting product. They also used it in religious ceremonies. You might not recognize their cocoa, though. Instead of consuming a sweet beverage, the Olmec, Mayans and Aztecs mixed cacao with savory spices like chili.

After the Spanish conquered Latin America, they brought cocoa back to Europe. And they made an important innovation: adding sugar, which greatly increased chocolate’s appeal to European taste buds.

Chocolate Gains Popularity:

The resulting concoctions, whether as liquid cocoa or solid chocolate, are still prized for their delicious flavor. In addition, scientists have been discovering previously unsuspected health benefits from this plant-derived food.

Last year, we heard from a physician who was quite unhappy about our comments on cocoa flavanols:

“Some of these products are touted to support brain and heart health. There is no evidence behind such claims. You’ve said cocoa flavanols improve health, and you should be ashamed of yourselves.”

Cocoa Flavanols in Chocolate Really Help Blood Vessels:

As it turns out, this doctor had not been following the medical research. Cocoa flavanols lower blood pressure (Cochrane Database of Systematic Reviews, Apr. 25, 2017),  possibly because they make blood vessels more flexible (Journal of Agricultural and Food Chemistry, Feb. 19, 2020).  Recent research confirms this action on blood vessels. People with type 2 diabetes benefit markedly (Food & Function, Oct. 17, 2022).

A randomized controlled trial of 100 middle-aged adults demonstrated that people consuming 450 mg of cocoa flavanols daily for a month reduce many important markers of cardiovascular risk (British Journal of Nutrition, Oct. 28, 2015).  A systematic review of 31 studies found that people consuming dark chocolate for at least two weeks lowered their systolic blood pressure by nearly 4 mm Hg (Foods, July 1, 2022).  When the daily dose of cocoa flavanols was at least 900 mg, researchers saw greater effects.

Considering Multiple Studies on Cocoa and Cardiovascular Risk Factors:

A new meta-analysis of randomized controlled trials has examined the impact of cocoa flavonoids on cardiovascular risk markers (Nutrients, June 18, 2024). The investigators identified 31 trials that lasted for more than a month and compared cocoa compounds to placebo. Nearly 2,000 volunteers participated in the trials. Cocoa flavonoids were consumed as supplements or in dark chocolate containing more than 70% cocoa.

No differences appeared in weight, BMI, waist size, triglycerides or HbA1c, a measure of blood glucose over time. However, cocoa compounds lowered cholesterol, fasting blood sugar and blood pressure.

The researchers concluded,

“The consumption of cocoa showed protective effects on major cardiometabolic risk markers that have a clinical impact in terms of cardiovascular risk reduction.”

Although the researchers note that people consuming cocoa compounds lowered their cholesterol modestly, they suggest that might make a difference over the long term.

Here is what they say:

“…regular dietary intake of cocoa is an interesting strategy for reducing the occurrence of cardiovascular events when considering individual levels of total cholesterol and LDL-c.”

Are There Downsides to Cocoa Flavanols?

What are the downsides of getting cocoa flavanols from dark chocolate? We certainly couldn’t consider candy bars to be health food. Among other things, eating enough chocolate to provide 450 to 900 mg of cocoa flavanols a day could result in quite a lot of calories. If you don’t have room in your diet for extra energy, you might want to consider cocoa flavanol supplements.

ConsumerLab.com recently published a review of dark chocolate, cocoa and cacao powders and supplements as sources of flavanols. The analysts warn that some of these sources have high levels of cadmium, a toxic heavy metal. They also found that levels of flavanols varied enormously among products, ranging from 2 to 993 mg in supplements and 2 to 351 mg in dark chocolate.

The analysis identified CocoaVia supplements as having reliably high levels of cocoa flavanols and low or nonexistent levels of contaminants. We must reveal that CocoaVia underwrites our public radio show and supports our newsletter. For more information about the best sources of cocoa flavanols, you may wish to subscribe to ConsumerLab.com and read their full report.

Consumer Reports, a different organization, also reviewed dark chocolate recently. Several popular brands have unacceptable levels of lead as well as cadmium.

Doctors may never consider chocolate as health food, but cocoa flavanols have earned their reputation as having a number of important benefits.

Danish Study Showed Potential of Chocolate Against Atrial Fibrillation:

The Danish Diet, Cancer and Health Study 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 Americans. 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 the Danish Study Showed:

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 (Heart, May 23, 2017). 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.

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 (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).

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies..
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Citations
  • Ried K et al, "Effect of cocoa on blood pressure." Cochrane Database of Systematic Reviews, Apr. 25, 2017. DOI: 10.1002/14651858.CD008893.pub3
  • Gröne M et al, "Cocoa flavanols improve endothelial functional integrity in healthy young and elderly subjects." Journal of Agricultural and Food Chemistry, Feb. 19, 2020. DOI: 10.1021/acs.jafc.9b02251
  • Bapir M et al, "Cocoa flavanol consumption improves lower extremity endothelial function in healthy individuals and people with type 2 diabetes." Food & Function, Oct. 17, 2022. DOI: 10.1039/d2fo02017c
  • Sansone R et al, "Cocoa flavanol intake improves endothelial function and Framingham Risk Score in healthy men and women: a randomised, controlled, double-masked trial: the Flaviola Health Study." British Journal of Nutrition, Oct. 28, 2015. DOI: 10.1017/S0007114515002822
  • Amoah I et al, "Effect of cocoa beverage and dark chocolate consumption on blood pressure in those with normal and elevated blood pressure: A systematic review and meta-analysis." Foods, July 1, 2022. DOI: 10.3390/foods11131962
  • Arisi TOP et al, "Effects of cocoa consumption on cardiometabolic risk markers: Meta-analysis of randomized controlled trials." Nutrients, June 18, 2024. https://doi.org/10.3390/nu16121919
  • Mostofsky E et al, "Chocolate intake and risk of clinically apparent atrial fibrillation: the Danish Diet, Cancer, and Health Study." Heart, May 23, 2017. http://dx.doi.org/10.1136/heartjnl-2016-310357
  • Grassi D et al, "Cocoa reduces blood pressure and insulin resistance and improves endothelium-dependent vasodilation in hypertensives." Hypertension, Aug. 2005. DOI: 10.1161/01.HYP.0000174990.46027.70
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