Supplement: Cacaoflavanolen

What Cocoa Flavanols Are, and How They Work

Cocoa flavanols are the flavan-3-ols, plant compounds in the cocoa bean. The same compounds are in green tea, apples, and berries. The best studied is (-)-epicatechin, the molecule most of the vascular research follows. In the blood-vessel lining, epicatechin raises how much nitric oxide the endothelium can make and keep available. Nitric oxide relaxes the vessel wall, so the arteries widen. Flow-mediated dilation measures that widening. Trials that supplied more than about 50 mg of epicatechin a day produced the larger blood-pressure results.

Anatomy of the Practice

1Within hours

A single flavanol-rich dose raises nitric oxide in the blood-vessel lining, and the arteries relax and widen. This shows up as improved flow-mediated dilation within one to two hours of eating it, the fastest and most reproducible effect in the research.

2Over two to eighteen weeks

Over two to eighteen weeks of daily cocoa, resting blood pressure settles slightly lower and stays there. The effect is small but consistent across the trials.

3Over years

One large trial tested whether the short-term vascular gains cut heart attacks and strokes. The main answer was no clear reduction. It did show a signal on cardiovascular death, and on memory in people who ate few flavanols to begin with.

Getting the Flavanols

Ways to Do It

Most of what sits in the candy aisle is a poor flavanol source. The options below run from free food up to a standardized supplement.

1

Get flavan-3-ols from everyday foodsFreeEasy

Green tea, apples, and berries carry flavan-3-ols from the same family, and a varied diet with these in it covers the compound class without any purchase or supplement. For most people, everyday foods are enough, and that varied diet is what the population studies were describing.

2

Unsweetened natural cocoa powder$Easy

Natural, non-alkalized cocoa powder keeps far more of its flavanols than Dutch-processed (alkalized) cocoa, so check the label for which one you are buying. A tablespoon stirred into oats, milk, or a smoothie gives you the compound without the sugar and fat of a bar. It tastes bitter, and that bitterness is the flavanols.

3

Dark chocolate, treated as a food$ to $$Easy

A higher cocoa percentage usually means more flavanols. Processing varies so much, though, that no bar reliably delivers a trial-sized dose, and every bar carries sugar and fat.

4

A standardized cocoa flavanol supplement$$Easy

The only dependable way to hit the trial dose is a supplement standardized for flavanol and epicatechin content. COSMOS used 500 mg of flavanols with 80 mg of epicatechin. This reproduces the studied dose instead of guessing at it.

What Changed

For years the message was that chocolate is good for the heart. It rested on short-term trials that lowered blood pressure and improved artery function, plus population studies where people who ate more cocoa had less heart disease. No one had run the long trial: until COSMOS gave 21,442 older adults a daily cocoa flavanol extract or a placebo, followed for a median 3.6 years.

But chocolate eaters differ in income, activity and diet, so those studies show association without proving cause.

On its main measure, a composite of cardiovascular events, the trial fell short of statistical significance, though the point estimate favored cocoa. The hazard ratio was 0.90 (95% CI 0.78 to 1.02, P=0.11). Among the participants who actually took the pills as directed, the reduction reached significance, at a hazard ratio of 0.85. One secondary measure, cardiovascular death, ran 27% lower in the cocoa group (hazard ratio 0.73, 95% CI 0.54 to 0.98).

Two companion trials looked at the brain. COSMOS-Mind found no change in overall thinking and memory over roughly 3 years. COSMOS-Web found no memory gain across everyone. Memory improved only in the subgroup who ate the fewest flavanols at baseline, and rising flavanol levels in their urine tracked those gains.

That leaves three verdicts, each resting on its own evidence:

• Blood pressure and artery function, at the flavanol doses the trials used: reasonably solid over the short term.
• Cardiovascular events over years: the largest trial missed its main measure, with a secondary signal on cardiovascular death that a dedicated trial would still have to confirm.
• Memory and cognition: not an across-the-board effect, and clearest in people whose diets were low in flavanols.

The Evidence, Graded

The blood-pressure and artery effects rest on meta-analyses of 35 short trials. The heart, mortality, and memory results come from one large supplement trial.

The Research & Studies

Everything here is based on the research we have collected and checked, sorted into groups and ordered with the strongest evidence first. Click any claim to open the studies behind it.

Heart And Vascular

Flavanol-rich cocoa lowers blood pressure about 2 mmHg, near 4 in people who start highModerate

In plain terms

Eating flavanol-rich cocoa nudged blood pressure down by about 2 points on average, a systolic drop of 1.76 mmHg, and closer to 4 points in people who started with high blood pressure.

In detail

Cochrane review of 35 randomized trials (40 comparisons, 2 to 18 weeks, mean 9 weeks) in 1,804 mainly healthy adults, mean flavanol dose 670 mg/day. Graded moderate quality; heterogeneity was unexplained by prespecified subgroups, and a sensitivity analysis excluding trials with industry-employed authors reduced the effect size.

Who this may not transfer to:Meta-analysis of 1,804 mostly healthy adults of both sexes over 2 to 18 weeks. The 4 mmHg figure is the hypertensive subgroup; a reader with normal blood pressure should expect the smaller 2 mmHg end.

The study · 1

Ried 2017, Cochrane Database Syst Rev · Cochrane Database Syst Rev

Cocoa relaxes the artery lining: flow-mediated dilation rises about 3% within hours, 1.3% over weeksModerate

In plain terms

Cocoa made the lining of blood vessels relax and widen more, a sign of healthier arteries, both within hours of eating it and over weeks.

In detail

Meta-analysis of 42 acute or short-term (up to 18 weeks) randomized trials in 1,297 participants. GRADE rated the evidence low to moderate, lowered for unclear allocation concealment and biomarker heterogeneity. Doses above 50 mg epicatechin/day produced larger blood-pressure effects.

Who this may not transfer to:1,297 adults of both sexes across 42 short trials. Flow-mediated dilation is a marker of arterial function measured over hours to 18 weeks, so it speaks to how the vessels behave, not to whether events fall over years.

The study · 1

Hooper 2012, Am J Clin Nutr · Am J Clin Nutr

COSMOS did not cut total cardiovascular events (HR 0.90, P=0.11) over 3.6 yearsModerate · no effect

In plain terms

In the largest trial, a daily cocoa flavanol supplement did not clearly cut the overall rate of heart attacks, strokes and related events, though the result leaned toward benefit and was significant among people who took it as directed.

In detail

COSMOS randomized 21,442 US adults (12,666 women aged 65+ and 8,776 men aged 60+) free of major cardiovascular disease and recent cancer to cocoa extract or placebo. The primary composite included MI, stroke, coronary revascularization, cardiovascular death, carotid artery disease, peripheral artery surgery, and unstable angina.

Who this may not transfer to:21,442 US adults, women 65+ and men 60+, free of major cardiovascular disease at entry. The null describes this older, initially healthy group taking a supplement, and does not speak to younger or higher-risk people.

The study · 1

Sesso 2022, Am J Clin Nutr (COSMOS) · Am J Clin Nutr

Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.

Cardiovascular death fell 27% in COSMOS (HR 0.73), a secondary endpointEmerging

In plain terms

In the same trial, fewer people in the cocoa group died of heart disease, though this was one of several secondary measures, not the main result the trial was built to test.

In detail

Prespecified secondary endpoint of COSMOS among 21,442 older US adults over a median 3.6 years. Other individual secondary endpoints (MI HR 0.87, stroke 0.91, revascularization 0.95) were neutral.

Who this may not transfer to:Same 21,442 older US adults as the primary analysis. This is one prespecified secondary endpoint among several, so it needs a trial built to test it before it carries to practice.

The study · 1

Sesso 2022, Am J Clin Nutr (COSMOS) · Am J Clin Nutr

Counts once: this finding and 1 other here come from the same source, so they are one body of evidence, not separate confirmations.

Cognition

Cocoa extract did not improve global cognition over 3 years (COSMOS-Mind)Moderate · no effect

In plain terms

A daily cocoa flavanol supplement did not improve overall thinking and memory in older adults over three years.

In detail

COSMOS-Mind, a substudy of 2,262 older adults (mean age 73, 60% women) using telephone-administered cognitive testing over 3 years. This is a substudy of a trial powered for cardiovascular and cancer outcomes.

Who this may not transfer to:2,262 older adults, mean age 73, 60% women, tested by telephone. The null is for overall thinking and memory in this general older sample.

The study · 1

Baker 2023, Alzheimers Dement (COSMOS-Mind) · Alzheimers Dement

Memory improved only in the lowest-flavanol subgroup; the overall endpoint was null (COSMOS-Web)Emerging

In plain terms

The supplement did not improve memory across everyone, but it did help the subgroup who ate the fewest flavanols to begin with, suggesting the benefit is about filling a gap, not adding a boost.

In detail

COSMOS-Web randomized 3,562 older adults to 500 mg cocoa flavanols/day or placebo for 3 years, with a urine flavanol biomarker in 1,361 of them. Habitual flavanol intake and diet quality correlated with hippocampal-dependent memory at baseline.

Who this may not transfer to:3,562 older adults of both sexes. The memory gain applies to the subgroup who ate the fewest flavanols to begin with, not to the whole group, whose primary endpoint was null.

The study · 1

Brickman 2023, Proc Natl Acad Sci U S A · Proc Natl Acad Sci U S A

Go Deeper

• Whole foods: the food-first case, where cocoa is one flavanol source among many.
• Omega-3 and fish oil: another supplement whose short-term markers looked strong and whose long-term event trials came in mixed, and a useful comparison for reading this kind of evidence.

The Chinese Medicine View

Cocoa is a New World food with no place in the classical Chinese materia medica, so nothing here is a traditional use. What the tradition offers is a way of reading any food by its flavor, temperature, and effect on a given constitution. By taste cocoa is bitter, and the bitter flavor is tied to draining, drying, and clearing heat downward. Sugar and rich fat turn it into a sweet, cloying, moistening food that the tradition reads as damp- and phlegm-forming. For someone already damp or phlegm-laden (sluggish, heavy, a coated tongue) that food feeds the accumulation. Cocoa also carries caffeine and theobromine, mild stimulants that read as warming and stirring. In someone already hot, restless, or short on sleep, a warming stimulant is a poor fit by this reasoning.

Both readings land on the same split: bitter, flavanol-rich cocoa is one food, and the sweet, damp-forming bar is another. A reading that weighs a food by who eats it treats them differently. If you work with a practitioner, this is a reasonable thing to ask about.

Cautions For This Practice

Everything to be aware of is here, in one place. This practice suits most healthy people; a few situations call for real care.

The sugar and fat in most chocolate

Most chocolate delivers its flavanol with a large load of sugar, fat, and calories. Candy is engineered around sugar and fat. The average American already takes in about 17 teaspoons of added sugar a day, past the 6 to 9 teaspoons the American Heart Association sets as a ceiling. If the goal is flavanols, unsweetened natural cocoa or a standardized supplement gets you there without the sugar.

Caffeine and theobromine

Cocoa contains caffeine and a related stimulant, theobromine. Dark chocolate and cocoa powder carry more than milk chocolate, enough to affect sleep, reflux, or a sensitive stomach in some people. It also counts if you are already limiting caffeine. Theobromine is toxic to dogs and cats at doses they reach easily, so keep cocoa and chocolate away from pets.

Heavy metals in some dark chocolate and cocoa

Independent testing has repeatedly found cadmium and lead in a share of dark chocolate and cocoa products. Cadmium comes up from the soil into the plant; lead arrives mostly after harvest. For an occasional treat this is minor. If you eat dark chocolate or cocoa daily, vary the brands you buy.

Blood pressure that is already low or medicated

The blood-pressure effect is small, so for most people it is not a problem. If you already run low, or take medication for high blood pressure, a daily flavanol dose lowers it a little more. Mention it to your clinician so the doses are set together.

A migraine trigger for some people

A minority of people with migraine find chocolate can precede an attack, though whether it triggers the headache or is a craving during the early phase of one is unsettled. If you notice a pattern for yourself, that observation is worth more than the group data.

Talk to a clinician before daily high-dose use if you are unwell or pregnant

Raise a daily supplement, or any condition-specific use, with your own clinician, especially in pregnancy or alongside other treatment.

Start slow, be smart, read the research, and consult a professional if you have any concerns. This is here to inform your choice, not make it for you.

Common Questions

Does eating dark chocolate actually lower blood pressure?

A little, from the flavanol content, which most bars barely contain. In people who begin high, flavanol-rich cocoa has trimmed systolic pressure by around 4 points; in everyone else the drop is smaller.

How much cocoa flavanol do the trials actually use?

More than a bar delivers. The blood-pressure trials averaged about 670 mg of flavanols a day, well past what processing leaves in even unsweetened cocoa.

Did the big trial prove cocoa prevents heart disease?

No, not on its main measure. Over about 3.6 years, COSMOS found no significant drop in total cardiovascular events, though the per-protocol group did benefit. Cardiovascular death, a secondary measure, was 27% lower. A secondary result can point the way, but a trial built to test it has to come next.

Is cocoa good for memory and thinking?

Mixed, and it looks like filling a gap. Over 3 years a daily flavanol supplement did not improve overall cognition, and it did not lift memory across everyone in a second trial. It did restore memory in the lowest-flavanol eaters, whose urine flavanol levels rose in step. The likeliest benefit is for diets low in these compounds.