High-Polyphenol Cocoa and Cardiovascular Health: 

When most people hear the word cocoa, they think of chocolate, dessert, and perhaps a guilty pleasure. But cocoa in its natural, minimally processed form is something very different from a typical chocolate candy bar.

Raw or minimally processed cocoa is one of the richest dietary sources of a family of plant compounds called polyphenols, particularly cocoa flavanols such as epicatechin, catechin, and procyanidins. These compounds have attracted considerable scientific attention because of their effects on the vascular system.

Research suggests that flavanol-rich cocoa can improve blood-vessel function, increase nitric oxide activity, modestly lower blood pressure, reduce arterial stiffness, and decrease several processes involved in the development of atherosclerosis.

That does not mean cocoa has been proven to dissolve existing arterial plaque. But the evidence suggests that high-polyphenol cocoa may favorably influence several of the biological mechanisms that contribute to plaque formation and cardiovascular disease.

The Difference Between Cocoa and Chocolate

Before discussing the research, it’s important to make a distinction.

The cardiovascular benefits associated with cocoa are primarily attributed to its flavanols and other polyphenols, not to sugar, cocoa butter, or chocolate itself.

Unfortunately, cocoa processing can dramatically reduce these compounds.

One particularly important process is alkalization, sometimes called “Dutch processing.” Cocoa is treated with alkaline compounds to reduce bitterness, darken the color, and create a smoother flavor.

The tradeoff can be a major reduction in flavanols.

A study analyzing commercial cocoa powders found average total flavanol concentrations of approximately:

• Natural cocoa: 34.6 mg/g
• Lightly alkalized cocoa: 13.8 mg/g
• Medium alkalized cocoa: 7.8 mg/g
• Heavily alkalized cocoa: 3.9 mg/g

In other words, heavily alkalized cocoa contained roughly 89% less total flavanols than natural cocoa in this analysis. The researchers found that flavanol concentrations progressively declined as alkalization increased. (⁠PubMed)

This is why choosing natural, non-alkalized, minimally processed cocoa or a product standardized for cocoa flavanols can be important when cardiovascular benefits are the goal.

1. Cocoa Flavanols Improve Endothelial Function

Perhaps the strongest evidence for cocoa involves the endothelium.

The endothelium is the thin layer of cells lining the inside of our arteries. It isn’t simply a passive lining. It actively regulates blood-vessel dilation, inflammation, blood clotting, blood pressure, and vascular repair.

Endothelial dysfunction is considered an important early feature of atherosclerosis.

One way researchers measure endothelial health is through flow-mediated dilation (FMD)—essentially measuring how effectively an artery expands in response to increased blood flow.

A meta-analysis examining cocoa flavanol trials found that cocoa flavanols significantly improved FMD. Across studies, participants receiving cocoa flavanols showed an average improvement of about 1.17 percentage points in FMD. (⁠PubMed)

A more recent large meta-analysis examining flavan-3-ol-rich foods found improvements in FMD following both acute and repeated consumption. (⁠OUP Academic)

Why is this important?

Healthy arteries should be flexible and responsive. When endothelial function improves, arteries are better able to relax and regulate blood flow.

2. Cocoa Helps the Body Produce Nitric Oxide

One of the primary mechanisms behind cocoa’s vascular benefits appears to involve nitric oxide (NO).

Endothelial cells produce nitric oxide, which signals the smooth muscle around blood vessels to relax.

The result is vasodilation—widening of the blood vessel.

Researchers have demonstrated that flavanol-rich cocoa increases circulating nitric oxide-related compounds and improves blood flow. Epicatechin, one of cocoa’s primary flavanols, appears to be particularly important in this response. (⁠PubMed)

Think of nitric oxide as part of the body’s natural system for telling an artery:

“Relax, open up, and let the blood flow.”

Improving nitric oxide availability may therefore help support healthier blood pressure, circulation, and endothelial function.

3. Cocoa May Modestly Lower Blood Pressure

The effect of cocoa on blood pressure has been examined in numerous controlled clinical trials.

An updated systematic review and meta-analysis of 25 randomized trials involving 1,167 participants found that cocoa flavanol consumption was associated with average reductions of approximately:

Systolic blood pressure: 2.7 mmHg

Diastolic blood pressure: 1.8 mmHg

The researchers also reported improvements in flow-mediated dilation and a modest improvement in pulse-wave velocity, a measure related to arterial stiffness. (⁠ScienceDirect)

These numbers may sound small, but cardiovascular health isn’t determined by one dramatic intervention. It often comes from the cumulative effect of multiple improvements in blood pressure, diet, exercise, blood sugar, lipids, inflammation, sleep, and lifestyle.

4. Cocoa May Reduce Arterial Stiffness

Healthy arteries are elastic.

As arteries become damaged through aging, high blood pressure, oxidative stress, metabolic dysfunction, inflammation, and atherosclerosis, they can gradually become stiffer.

Researchers frequently measure this using pulse-wave velocity (PWV).

The recent meta-analysis mentioned above found that cocoa flavanol consumption improved PWV by approximately 0.20 meters per second, although the certainty of evidence for vascular outcomes was more limited than the evidence for blood pressure. (⁠ScienceDirect)

Combined with improvements in endothelial function, this suggests that cocoa flavanols may help arteries behave more like healthy, responsive blood vessels.

5. Cocoa May Help Protect LDL From Oxidation

This is particularly interesting when discussing atherosclerosis.

LDL cholesterol alone does not tell the entire cardiovascular story. Modified and oxidized LDL particles can contribute to the inflammation involved in atherosclerotic plaque formation.

Macrophages in the arterial wall can take up oxidized LDL, contributing to the development of lipid-filled foam cells, an important component of early atherosclerotic lesions.

Cocoa polyphenols appear to influence this process.

In one controlled human study, participants consumed cocoa powder and dark chocolate, providing approximately 466 mg of procyanidins per day. LDL particles became more resistant to oxidation, with LDL oxidation lag time increasing by approximately 8% compared with the control diet. (⁠PubMed)

Another study involving 160 participants examined several amounts of high-polyphenol cocoa powder. Researchers reported reductions in oxidized LDL, and among participants with higher baseline LDL cholesterol, cocoa consumption was associated with reductions in LDL cholesterol, oxidized LDL, and ApoB along with an increase in HDL cholesterol. (⁠PubMed)

This doesn’t mean cocoa “cleans cholesterol out of the arteries.” Rather, it suggests that cocoa polyphenols may help modify some of the processes that make circulating lipoproteins more atherogenic.

6. Cocoa May Reduce Oxidative Stress and Vascular Inflammation

Atherosclerosis isn’t simply cholesterol accumulating inside a pipe.

It is a complex biological process involving lipoproteins, endothelial injury, oxidative stress, immune activation, inflammation, smooth-muscle cells, and eventually calcification and remodeling of the arterial wall.

That makes cocoa’s effects on oxidative stress and inflammatory signaling particularly interesting.

In a randomized controlled crossover study, researchers tested cocoa providing 0, 80, 200, 500, or 800 mg of cocoa flavonoids per day.

Higher-flavonoid cocoa reduced several markers associated with endothelial activation, inflammation, and oxidative stress, including sICAM-1, sCD40L, and F2-isoprostanes. (⁠PubMed Central (PMC))

These findings provide another potential mechanism through which cocoa could help create a vascular environment less favorable to the development and progression of atherosclerosis.

So, Can Cocoa Reduce Arterial Plaque?

Here we need to separate what is biologically plausible from what has actually been demonstrated in humans.

We have human evidence that cocoa flavanols can:

• Improve endothelial function
• Increase nitric oxide activity
• Improve vasodilation
• Modestly reduce blood pressure
• Modestly improve arterial stiffness
• Reduce LDL oxidation
• Influence oxidative stress and inflammatory signaling

All of these factors are relevant to atherosclerosis biology.

However, we don’t currently have convincing clinical evidence that eating cocoa causes established coronary or carotid plaque to regress.

That’s an important distinction.

Rather than calling cocoa a “plaque remover,” I prefer to think of high-polyphenol cocoa as a vascular-supportive food that may help address several mechanisms involved in plaque development and cardiovascular risk.

What About Actual Heart Attacks and Cardiovascular Events?

One of the largest studies in this field was the COcoa Supplement and Multivitamin Outcomes Study (COSMOS).

More than 21,000 older adults were randomized to receive either a cocoa extract containing 500 mg of cocoa flavanols per day, including 80 mg of epicatechin, or placebo.

During a median follow-up of 3.6 years, cocoa flavanols did not significantly reduce the trial’s primary outcome of total cardiovascular events.

However, cardiovascular deaths were lower in the cocoa group, a secondary finding that the researchers considered encouraging but requiring further investigation. (⁠PubMed)

That’s an excellent example of why we shouldn’t turn promising nutritional research into claims that a food prevents or cures cardiovascular disease.

The research is encouraging, but it’s still evolving.

How Much Cocoa?

This is where things get tricky because a tablespoon of cocoa powder doesn’t automatically equal a specific dose of cocoa flavanols.

Flavanol content varies tremendously by cocoa bean, fermentation, roasting, alkalization, manufacturing, and storage.

Clinical studies have used a wide range of flavanol doses.

A 2019 meta-analysis found a nonlinear relationship between cocoa flavanol intake and endothelial function, with the strongest modeled response occurring around 710 mg of total flavanols per day. However, the researchers also noted substantial variability and risk-of-bias concerns among many of the included studies. (⁠PubMed)

The COSMOS trial used 500 mg of cocoa flavanols per day. (⁠PubMed)

This does not mean everyone needs 500–700 mg per day. It means that when choosing cocoa specifically for cardiovascular purposes, knowing the flavanol content is far more useful than simply knowing how many grams of cocoa are in the product.

What Should You Look For?

If your goal is maximizing cocoa’s cardiovascular benefits, look for cocoa that is:

Natural and non-alkalized
Avoid “Dutch processed” or heavily alkalized cocoa when maximizing flavanols is the objective.

High in cocoa flavanols or polyphenols
Ideally, choose a product that lists flavanol content on the label or provides independent testing.

Unsweetened
Adding large amounts of sugar defeats much of the purpose of turning cocoa into a cardiovascular-health food.

Minimally processed
Processing conditions matter because flavanols are sensitive to several stages of cocoa production.

And remember: the word “raw” alone does not guarantee high flavanol content. A measured or standardized flavanol content is a much better indicator.

Easy Ways to Use High-Polyphenol Cocoa

Natural unsweetened cocoa can be surprisingly easy to incorporate into a healthy diet.

Try adding it to:

• Protein or nutritional shakes
• Plain Greek or plant-based yogurt
• Chia pudding
• Overnight oats
• Smoothies
• Coffee
• Unsweetened almond or coconut milk
• Homemade energy bites
• Nut or seed butter
• Healthy homemade desserts

A little monk fruit or allulose can offset cocoa’s natural bitterness without adding large amounts of sugar.

Cocoa Is Part of the Strategy—not the Entire Strategy

No single food reverses cardiovascular disease.

If someone already has significant atherosclerotic plaque, cocoa shouldn’t replace appropriate medical evaluation, blood-pressure control, lipid management, exercise, smoking cessation, weight management, glucose control, sleep, and a nutrient-dense diet.

But as part of an overall cardiovascular lifestyle, high-polyphenol cocoa is a fascinating food.

Its flavanols interact with some of the very systems that determine vascular health: nitric oxide, endothelial function, oxidative stress, inflammation, LDL oxidation, arterial stiffness, and blood pressure.

And that’s what makes cocoa so interesting.

The real cardiovascular story isn’t:

“Eat chocolate and prevent heart disease.”

It is:

Choose minimally processed, high-flavanol cocoa, and you may be giving your cardiovascular system a concentrated source of plant compounds capable of supporting healthier blood-vessel function.

That’s a much different—and much more scientifically supported—message.

Scientific References

Baba, S., et al. (2007). Plasma LDL and HDL cholesterol and oxidized LDL concentrations are altered in normo- and hypercholesterolemic humans after intake of different levels of cocoa powder. The Journal of Nutrition, 137(6), 1436–1441. (⁠PubMed)

Grassi, D., et al. (2023). Cocoa consumption decreases oxidative stress, proinflammatory mediators and lipid peroxidation in healthy subjects: A randomized placebo-controlled dose-response clinical trial. High Blood Pressure & Cardiovascular Prevention, 30, 219–225. (⁠Springer)

Miller, K. B., et al. (2008). Impact of alkalization on the antioxidant and flavanol content of commercial cocoa powders. Journal of Agricultural and Food Chemistry, 56(18), 8527–8533. (⁠PubMed)

Schroeter, H., et al. (2006). (-)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans. Proceedings of the National Academy of Sciences, 103(4), 1024–1029. (⁠PubMed)

Sun, Y., Zimmermann, D., De Castro, C. A., & Actis-Goretta, L. (2019). Dose-response relationship between cocoa flavanols and human endothelial function: A systematic review and meta-analysis of randomized trials. Food & Function, 10(10), 6322–6330. (⁠PubMed)

Wan, Y., Vinson, J. A., Etherton, T. D., Proch, J., Lazarus, S. A., & Kris-Etherton, P. M. (2001). Effects of cocoa powder and dark chocolate on LDL oxidative susceptibility and prostaglandin concentrations in humans. American Journal of Clinical Nutrition, 74(5), 596–602. (⁠PubMed)

Sesso, H. D., et al. (2022). Effect of cocoa flavanol supplementation for the prevention of cardiovascular disease events: The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) randomized clinical trial. American Journal of Clinical Nutrition, 115(6), 1490–1500. (⁠PubMed)

Disclaimer: This article is for educational purposes and is not intended to diagnose, treat, cure, or prevent any disease. Individuals with cardiovascular disease or those taking blood-pressure, anticoagulant, or other prescription medications should discuss significant dietary or supplement changes with their healthcare provider.