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What Is the Evidence That Cocoa Flavanols Improve Health?

A number of studies lead to the conclusion that cocoa flavanols improve health. But that doesn't make chocolate bars health food.
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As Valentine’s Day approaches, you will no doubt see a number of feature pieces suggesting that chocolate is actually good for you. These stories may be counterbalanced by others pointing out that chocolate is high in sugar and fat, and therefore also pretty high in calories. Consequently, they say, chocolate is not good for you at all. In truth, though the question is really about the plant compounds in chocolate. Is there real evidence that cocoa flavanols improve health?

Do Cocoa Flavanols Improve Health or Harm It?

Q. As a physician, I’m concerned about the ethics of advertising supplements. 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.

A. There are certainly products being advertised that are not supported by clinical trials. We definitely share your concerns about them. We disagree about cocoa flavanols, however.

When it comes to CocoaVia, the underwriter on our syndicated radio show, there is a substantial body of research. Cocoa flavanols can lower blood pressure modestly (Cochrane Database of Systematic Reviews, April 25, 2017).  They may do this by making blood vessels more flexible (Journal of Agricultural and Food Chemistry, online Aug. 12, 2019).  In addition, cocoa flavanols can reduce markers of inflammation (Frontiers in Immunology, April 24, 2019). 

Cocoa Flavanols and the Brain:

As for cognitive function, researchers have done fewer studies.

However, a systematic review of 12 studies found

a positive effect of cocoa polyphenols on memory and executive function” (Plant Foods for Human Nutrition, Jan. 13, 2020). 

In addition, Harvard researchers are currently conducting a large placebo-controlled study to see whether cocoa flavanols improve health. The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) has enrolled more than 18,000 older individuals who will take either cocoa flavanols or placebo plus multivitamin or placebo for four years. Beyond cardiovascular outcomes and cancer, the researchers are also collecting information on cognitive function, macular degeneration and cataracts. As the study is still underway, we shall have to wait several years for the scientists to finish collecting and analyzing all the data before we sill know what it can tell us about cocoa flavanols and the aging brain.

Where Can You Find Cocoa Flavanols?

We’ve already mentioned the calories in chocolate candy. The compounds themselves do not provide many calories, but candy certainly can. Moreover, not all chocolate candy is rich in cocoa flavanols. When we are looking for a good source of these compounds, we start with CocoaVia. Yes, they do underwrite our radio show. But they also provide the highest amount of cocoa flavanols per serving (450 mg) with very low levels of the toxic element cadmium. Chocolate really doesn’t come close.

To find other sources, we like to check with ConsumerLab.com. They review cocoa, chocolate and supplements and rank them according to flavanol and cadmium content. Ideally, you want more flavanols and less cadmium. Montezuma’s Dark Chocolate Absolute Black scores well with respect to other dark chocolates. (Milk chocolate doesn’t have enough cocoa flavanols to compete.) 

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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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  • Ried K et al, "Effect of cocoa on blood pressure." Cochrane Database of Systematic Reviews, April 25, 2017. DOI: 10.1002/14651858.CD008893.pub3
  • Grone M et al, "Cocoa flavanols improve endothelial functional integrity in healthy young and elderly subjects." Journal of Agricultural and Food Chemistry, online Aug. 12, 2019. DOI: 10.1021/acs.jafc.9b02251
  • Ruiz-Léon AM et al, "Clinical advances in immunonutrition and atherosclerosis: A review." Frontiers in Immunology, April 24, 2019. DOI: 10.3389/fimmu.2019.00837
  • Barrera-Reyes PK et al, "Effects of cocoa-derived polyphenols on cognitive function in humans. Systematic review and analysis of methodological aspects." Plant Foods for Human Nutrition, Jan. 13, 2020. DOI: 10.1007/s11130-019-00779-x
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comments (11 total)
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I too am enrolled in the COSMOS study. It has been interesting to correspond with them about the possible interactions with various health issues.

What is the COSMOS Trial?

It is an ongoing randomized controlled trial of multivitamins and cocoa flavanols. Dr. JoAnn Manson of Harvard is principal investigator.

How does grocery store-purchased, unsweetened, powdered baking chocolate rank in tests for anti-oxidant value?

Usually pretty good. Bakers unsweetened came out well in the ConsumerLab.com test.

Unsweetened cocoa powder and 85% dark chocolate has helped tremendously with my digestive system. I don’t have a gall bladder anymore and suffer from serious diarrhea. The dark chocolate definitely helps. There are supportive articles to research.

I’m a participant in the COSMOS trial. Happy to do my part in this research.

Some doctors think they do no good & some think they are harmful. Yet some of these same doctors will prescribe meds that have horrible side effects & then deny the meds are the problem. I’ve been studying & using medicinal herbs for 40+ years. My health is excellent yet I routinely have doctors tell me I’m doing myself more harm than good.

I was told to avoid chocolate because of its caffeine for heart rate and its high oxalate content for calcium oxalate kidney stone formation. I would love to know if this supplement would bypass those drawbacks.

Yes. Those 450 mg of cocoa flavanols are in 1500 mg cocoa extract. 1.5 gm of cocoa is just not enough to provide much caffeine or oxalate.

I did try the CocoaVia capsules for a few months, but discontinued it due to the high cost and no discernible change during the time I tried them. I’m afraid I’ll just have to get what little cocoa flavanols are available in chocolate. It would be helpful to many of us if this supplement were available at a more reasonable price so a longer-term trial could be conducted on a personal basis.

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