Can Chocolate Really Benefit Your Heart?

Chocolate brownies on a plate.
Chocolate is good for your health in several ways. (Image credit: Chocolate brownies photo via Shutterstock)

Chocolate is good for your heart — sort of, maybe.

Eating up to 3.5 ounces (100 grams) of chocolate daily is linked with lowered risks of heart disease and stroke, scientists reported today (June 15) in the journal Heart. That amount of chocolate is equal to about 22 Hershey's Kisses, two Hershey bars or two bags of M&M's, depending on how you want to divvy up this good news.

"There does not appear to be any evidence to say that chocolate should be avoided in those who are concerned about cardiovascular risk," the researchers concluded in their paper. Their new study is based on a meta-analysis of eight previously published studies involving a total of nearly 158,000 people.

One key finding was that people who ate chocolate regularly had up to an 11 percent lower risk of developing cardiovascular disease and a 23 percent lower risk of having a stoke, compared with nonchocolate eaters. (Yes, remarkably, they exist.)

However, the analysis comes with more caveats than Almond Joy has nuts. For example, exactly what it is about chocolate that might impart health benefits is not clear.  The scientists could not determine a cause-and-effect relationship between the two, and the observed benefits might be nothing more than a mirage, a limitation of the study design. [5 Wacky Things That Are Good for Your Health]

"There is, of course, a theoretical plausible explanation of why eating chocolate in moderation may expose some [people] to compounds — for example, flavonols — which are potentially good for risk reduction through cholesterol- and blood-pressure-lowering effects," said Dr. Phyo Myint, a senior author of the study and a professor at the University of Aberdeen School of Medicine and Dentistry in Scotland.

Myint cited numerous studies demonstrating that flavonols —  which are found in many plant-based foods, including cocoa — can lower blood pressure, improve blood flow to the brain, and make blood platelets less sticky and less likely to clot and cause a stroke.

But the majority of the participants in the eight studies in the new analysis got their chocolate by eating milk chocolate, which has considerably lower levels of flavonols than dark chocolate. This left the researchers to speculate that milk components in the chocolate — namely, calcium and fatty acids — may explain the observed effect.

There are, however, several other plausible explanations for the results that would suggest that eating a lot of chocolate isn't necessarily healthy, the researchers admitted. For example, the people in the study who ate the most chocolate — more than 100 grams daily — were younger adults, who tend not to have heart problems.

Similarly, the researchers said the finding might be due to "reverse causation," meaning that the people with a higher risk of cardiovascular disease avoid eating chocolate, while those who are healthier eat more. The researchers also noted that consuming too much candy and other high-calorie, sugary foods could lead to dental cavities, obesity and diabetes.

Although the risk reduction linked with chocolate consumption was statistically significant, the benefits are not particularly striking compared with those of other dietary practices associated with heart health. For example, outside the context of chocolate, the risk of developing heart disease for these participants given their age was 14.4 percent, on average, Myint said. Therefore, reducing this risk by 11 percent would lower the heart disease risk to 12.8 percent.

The study could not differentiate between the types of milk chocolate consumed, and this could have health implications as well. Myint's hometown of Aberdeen is where people devised the now infamous deep-fried Mars bar, he said.

"The key is only to have moderate consumption [of chocolate] and ensure one does not exceed the calorie intake recommended for their height or weight," Myint told Live Science.

Follow Christopher Wanjek @wanjek for daily tweets on health and science with a humorous edge. Wanjek is the author of "Food at Work" and "Bad Medicine." His column, Bad Medicine, appears regularly on Live Science.

Christopher Wanjek
Live Science Contributor

Christopher Wanjek is a Live Science contributor and a health and science writer. He is the author of three science books: Spacefarers (2020), Food at Work (2005) and Bad Medicine (2003). His "Food at Work" book and project, concerning workers' health, safety and productivity, was commissioned by the U.N.'s International Labor Organization. For Live Science, Christopher covers public health, nutrition and biology, and he has written extensively for The Washington Post and Sky & Telescope among others, as well as for the NASA Goddard Space Flight Center, where he was a senior writer. Christopher holds a Master of Health degree from Harvard School of Public Health and a degree in journalism from Temple University.