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Does chocolate have an effect on heart health?

A recent study attempted to see if consuming chocolate improved heart health and reduced cardiovascular disease. Given how often I see that chocolate is considered a “healthy food,” it was good to see some actual peer-reviewed scientific research that addressed these claims.

You can assume that if this study showed that chocolate had a positive benefit to your heart health, all the major chocolate manufacturers would be running advertising claiming the benefit. Since they did not do that, you can assume that the study probably was negative.

As I usually do, I will provide you with the actual results of the study plus an analysis of the study itself. Sorry to break this to the reader, but chocolate is delicious, and it does not help your heart.

sweet chocolate bars on plate
Photo by Anete Lusina on

Chocolate and heart health paper

In a paper published on 7 June 2022 in the American Journal of Clinical Nutrition, Howard D. Sesso, ScD, MPH, Division of Preventative Medicine, Harvard Medical School, and colleagues developed the COcoa Supplement and Multivitamin Outcomes Study (COSMOS) study to examine the effects of chocolate and multivitamins on heart health. The COSMOS study also included research on the effects of chocolate and multivitamins on cognitive health and dementia. Still, those results are published in a separate paper which I will review in a separate article.

The researchers conducted a randomized, double-blind, placebo-controlled trial of cocoa extract supplementation and multivitamins for the prevention of cardiovascular disease and cancer among 21,442 US adults (12,666 women aged ≥65 y and 8776 men aged ≥60 y), free of significant cardiovascular disease and recently diagnosed cancer. The intervention phase was from June 2015 through December 2020.

There were four separate groups of participants — chocolate plus multivitamin, chocolate plus placebo, placebo plus multivitamin, and placebo plus placebo.

Before I continue, I want to make it clear that the participants in this clinical trial did not have a bag of M&Ms or Hershey’s bar as the chocolate supplement — they were given the supplement orally in a capsule that contained cocoa powder.

I am going to focus on the chocolate supplement data. Here are the key results:

  • The chocolate supplement on the risks of all-cause mortality — none.
  • Effect on the risk of total cardiovascular events — none.
  • Effect on the risk of myocardial infarctions (heart attacks) — none.
  • Effect on the risk of stroke — none.
  • Effect on coronary revascularization — none.
  • Effect on the risk of cancer — none.

The authors concluded:

Cocoa extract supplementation did not significantly reduce total cardiovascular events among older adults.

In a separate article that examined the data from the COSMOS study, the researchers reviewed the effects of multivitamins on cardiovascular outcomes and cancer. The same thing was found as they did with the chocolate analysis — there was no difference in the risk of cardiovascular disease or cancer from consumption of multivitamins.

photo of a chocolate dessert in a glass
Photo by Angela Khebou on


The study did show a 27% reduction in cardiovascular death in the chocolate group compared to the placebo. However, given that chocolate did not affect any of the cardiovascular outcomes, like stroke and heart attacks, I am not going to embrace that small finding.

I criticize nutritional studies because they cannot account for confounding data, selection bias, and other issues. Most importantly, most of these studies show correlation but fail to show causation.

Overall, this is an excellent study that uses a double-blind clinical trial to show us that chocolate and multivitamins don’t do much for your heart health. Stick to exercise and a good diet.


Michael Simpson
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