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Research on cocoa and the heart focuses on cocoa flavanols, plant compounds found mostly in minimally processed cocoa. In controlled studies, flavanol-rich cocoa improved how easily blood vessels widen, an effect linked to higher nitric oxide activity, and a Cochrane review found a small average drop in blood pressure of about 2 mmHg. Most of this research used standardized, high-flavanol cocoa products, not sweetened hot chocolate or candy.
Here is what the studies actually measured, what the largest trial found, what U.S. and European regulators say, and how everyday cocoa compares with the amounts researchers used.
What in cocoa do heart researchers study?
| Compound | What it is | Why researchers look at it |
|---|---|---|
| Flavanols (epicatechin, catechin, procyanidins) | Polyphenols concentrated in cacao beans | The main focus of vascular studies; epicatechin is the best-studied single compound |
| Theobromine | A mild stimulant related to caffeine | Studied for small effects on blood vessels and alertness |
| Minerals | Magnesium, potassium, copper, iron | Nutrients that play normal roles in heart and muscle function |
| Fiber | About a third of cocoa powder’s weight | Part of an overall eating pattern that researchers track |
Flavanol levels vary a lot from one cocoa to another; our guide to flavanols in cocoa powder lists typical amounts, and epicatechin in cocoa powder covers the single compound most studies track.
How do cocoa flavanols affect blood vessels?
The most consistent finding is on endothelial function, the ability of the inner lining of blood vessels to relax and let blood flow. Researchers measure it with flow-mediated dilation (FMD), an ultrasound test of how much an artery widens after a brief squeeze. In a much-cited 2006 study in PNAS, drinking flavanol-rich cocoa raised FMD within about two hours, and the effect tracked the rise of epicatechin in the blood. The researchers linked it to more nitric oxide, a molecule the vessel lining releases to signal the surrounding muscle to relax.
That is the “something rising in the blood” behind many headlines: after a flavanol-rich drink, epicatechin levels in the blood peak within a couple of hours, and markers of nitric oxide activity go up with them. Based on this body of evidence, the European Food Safety Authority (EFSA) concluded in 2012 that 200 mg of cocoa flavanols a day helps maintain the elasticity of blood vessels, which contributes to normal blood flow, a claim the EU allows only for products that deliver that amount.
Does cocoa lower blood pressure?
A little, on average, in short studies. The 2017 Cochrane review “Effect of cocoa on blood pressure” pooled 40 treatment comparisons with 1,804 mostly healthy adults, mostly lasting 2 to 18 weeks. Flavanol-rich cocoa products lowered systolic and diastolic blood pressure by about 1.8 mmHg each compared with control, with a larger drop of around 4 mmHg systolic in the small group of studies in people with high blood pressure. The reviewers rated the evidence as low quality, because results varied between studies and some trials were industry funded.
| Study | What was tested | Main finding |
|---|---|---|
| Schroeter et al., PNAS 2006 | Flavanol-rich cocoa drink vs low-flavanol drink | Blood vessels widened more within hours; linked to epicatechin and nitric oxide |
| EFSA scientific opinion, 2012 | Review of vascular studies | 200 mg cocoa flavanols/day help maintain blood vessel elasticity |
| Cochrane review, 2017 | 40 comparisons, 1,804 adults, 2 to 18 weeks | Average blood pressure about 1.8 mmHg lower; low-quality evidence |
| COSMOS, 2022 | 500 mg/day cocoa flavanol supplement vs placebo, 21,442 adults, about 3.6 years | Total cardiovascular events not significantly different; cardiovascular deaths 27% lower (secondary outcome) |
What did the COSMOS trial find?
COSMOS is the largest trial so far. More than 21,000 older U.S. adults took either a cocoa extract supplement providing 500 mg of flavanols a day or a placebo for a median of 3.6 years. The main outcome, total cardiovascular events, was 10% lower in the cocoa group, which was not statistically significant. A secondary outcome, death from cardiovascular causes, was 27% lower. The investigators called the results promising but not definitive and said they need confirmation. Two details matter for cocoa lovers: the trial used capsules, not cocoa powder or chocolate, and the supplements were provided by industry partners.
What does the FDA say about cocoa flavanols?
In February 2023, the FDA said it would not object to a qualified health claim for one specific product type: high-flavanol cocoa powder containing at least 4% naturally conserved cocoa flavanols. The required wording states that cocoa flavanols in high-flavanol cocoa powder may reduce the risk of cardiovascular disease, and that the FDA has concluded there is very limited scientific evidence for the claim. The FDA added that the claim does not apply to regular cocoa powder, to foods made with regular cocoa powder, or to chocolate. In other words, the agency recognized a narrow, weak link for a specialized ingredient, not a general benefit of cocoa.
How does everyday cocoa compare with study amounts?
Average values give a rough sense of scale. A study of commercial cocoa powders found about 35 mg of flavanols per gram in natural (non-alkalized) cocoa and 4 to 14 mg per gram in Dutch-process cocoa, depending on how strongly it was alkalized.
| Source | Flavanols, approximate |
|---|---|
| 1 tbsp natural cocoa powder (average) | About 190 mg |
| 1 tbsp heavily alkalized (Dutch) cocoa | About 20 mg |
| EFSA reference amount | 200 mg a day |
| COSMOS supplement | 500 mg a day |
Individual products vary widely, and baking with alkaline leaveners lowers flavanols further, so these are averages, not label values. The practical takeaway is about processing: the less a cocoa is alkalized and heated, the more flavanols it tends to keep.
How can cocoa fit into a heart-friendly routine?
- Choose unsweetened cocoa and sweeten lightly. Many hot cocoa mixes are mostly sugar; the American Heart Association suggests limiting added sugar to about 25 g a day for women and 36 g for men.
- Make it a drink or a no-bake food: a mug of hot chocolate made with cocoa powder, a cacao smoothie or chocolate overnight oats.
- Prefer natural cocoa when flavanols matter to you; our explainer on “processed with alkali” shows how to spot Dutch-process cocoa on a label.
- Keep the bigger picture: no single food replaces an overall eating pattern, activity and your doctor’s advice.
Grevista is a natural, non-alkalized cocoa powder from single-origin Trinitario cacao grown in Đắk Lắk, Vietnam, with its lab results published on our lab results page. See sizes on the Grevista cocoa powder page.
Frequently asked questions
Is hot chocolate good for your heart?
The research is on cocoa flavanols, not on sweetened drinks. A mug made with unsweetened cocoa and little sugar is a different food from a sugary mix, but no hot chocolate is a treatment for heart disease.
Does dark chocolate have the same effect?
The FDA found no credible studies supporting a link between high-flavanol dark chocolate and lower heart disease risk, and chocolate also brings sugar and fat. Most positive studies used cocoa drinks or extracts.
Why does cocoa increase nitric oxide?
Studies suggest that epicatechin and related flavanols support the enzyme that makes nitric oxide in the blood vessel lining, which helps vessels relax. The effect appears within hours and fades within a day.
Can cocoa replace blood pressure medication?
No. The average effect in studies was small. Talk to your doctor before changing any treatment.
Sources
- U.S. Food and Drug Administration, “FDA Announces Qualified Health Claim for Cocoa Flavanols in High Flavanol Cocoa Powder and Reduced Risk of Cardiovascular Disease,” February 3, 2023 (checked October 27, 2026).
- Sesso HD et al., “Effect of cocoa flavanol supplementation for the prevention of cardiovascular disease events: the COSMOS randomized clinical trial,” American Journal of Clinical Nutrition, 2022;115(6):1490–1500.
- Ried K, Fakler P, Stocks NP, “Effect of cocoa on blood pressure,” Cochrane Database of Systematic Reviews, 2017, CD008893.pub3.
- Schroeter H et al., “(−)-Epicatechin mediates beneficial effects of flavanol-rich cocoa on vascular function in humans,” PNAS, 2006;103(4):1024–1029.
- EFSA Panel on Dietetic Products, Nutrition and Allergies, scientific opinion on cocoa flavanols and maintenance of normal endothelium-dependent vasodilation, EFSA Journal, 2012;10(7):2809.
- Miller KB et al., impact of alkalization on the flavanol content of commercial cocoa powders, Journal of Agricultural and Food Chemistry, 2008.
- American Heart Association, added sugars recommendations.
This article summarizes published research and is not medical advice. Written by the Grevista Editorial Team. Last updated November 2026. How we check facts: Editorial Policy.