Flavan-3-ols: The 400 to 600 mg Heart Target Most Miss

You already know the heart-health basics. Move more, sit less, cut the salt, sleep well. All of it holds up in the research. There is one more lever most people in London walk straight past, and it sits in the tea caddy and the fruit bowl.

The lever is a group of plant compounds called flavan-3-ols. In 2022 the Academy of Nutrition and Dietetics published the first dietary guideline written for a bioactive compound, with a clear daily target for heart and metabolic health. Most UK adults fall short of it. Here is what the evidence shows and how to reach the target from ordinary food.

What flavan-3-ols are

Flavan-3-ols are a subgroup of flavonoids, the natural compounds found in plants. The two you meet most are epicatechin and catechin. They turn up in tea, both green and black, in apples, in berries, in cocoa, and in smaller amounts in grapes and some nuts. The 2022 guideline names tea as the richest common source, and in a typical UK diet it does most of the heavy lifting, which puts the target within easy reach for people who already drink it.

Their main job in the body sits at the lining of your blood vessels, a single layer of cells called the endothelium. Healthy endothelium relaxes and widens arteries on demand, which keeps blood flowing and pressure in check. Flavan-3-ols support this function, and that is the mechanism behind most of the heart benefits below.

What the evidence shows

The blood pressure signal is the most consistent. A Cochrane review from 2017 pooled trials of flavanol-rich cocoa and found an average drop of about 1.8 mmHg in both systolic and diastolic blood pressure, rated as moderate-quality evidence. The effect was larger in people who started with raised readings. The reviewers noted a caveat worth respecting: several trials were funded by companies with a commercial interest, and those trials reported slightly larger effects.

Artery function points the same way. Within the same body of randomised trials behind the guideline, researchers measured flow-mediated dilation, a direct test of how well arteries widen on demand, and cocoa flavanols improved it. This matters because poor dilation predicts higher future cardiovascular risk, so moving the marker in the right direction is a meaningful signal. The evidence also points to a ceiling. Benefits level off once intake is adequate, which means more is not better without limit.

The largest test of hard outcomes is COSMOS, which followed 21,442 US adults aged 60 and over who took either a cocoa extract giving 500 mg of flavanols a day or a placebo. The headline needs care. The primary endpoint, total cardiovascular events, did not reach statistical significance. A pre-specified secondary endpoint, death from cardiovascular disease, was 27 percent lower in the cocoa flavanol group. That is a promising signal, not settled proof, and it is one reason the dietary guideline points to food rather than to supplements.

Blood pressure and artery function are not the whole story. When the Academy of Nutrition and Dietetics panel weighed the evidence for the 400 to 600 mg range, it concluded this level of flavan-3-ol intake supports blood pressure, blood cholesterol and blood sugar together. Those three sit at the centre of cardiometabolic risk, which is why the panel treated flavan-3-ols as a broad supportive nutrient rather than a single-target fix. The guidance rested on a large base, 157 randomised controlled trials and 15 cohort studies, so the direction of effect is well supported even where the size of each effect is modest.

One more point keeps the evidence honest. The benefits are real but small, and they work at the margin. Flavan-3-ols nudge the numbers that matter over weeks and months. They sit alongside the parts of a routine that move the dial hardest, regular movement, decent sleep, a plate built on whole foods, and, where a doctor prescribes it, medication. Read this way, the daily target is a low-cost habit worth adding, not a headline cure to chase.

Who benefits most

Two groups stand to gain the most. The first is people with raised blood pressure. In the Cochrane review, the fall in blood pressure was larger in those who started with higher readings, so the everyday benefit lands hardest where the risk is highest. The second is older adults. COSMOS enrolled adults aged 60 and over, and that is the stage of life where cardiovascular risk climbs and small, steady gains add up over the years. If you sit in either group, a daily flavan-3-ol habit is a low-cost addition to the basics your GP already recommends.

Most other adults still take something from it. Better artery function and a modest effect on blood pressure are worth having across a lifetime, and the food sources bring fibre, vitamins and other plant compounds along with them. The aim is not to chase a single number. It is to add a steady, low-risk habit that supports the parts of your routine already doing the heavy lifting.

How to reach 400 to 600 mg a day

The guideline is deliberately food-based. The panel named tea, apples, berries and cocoa as the practical sources, and told people to favour foods rich in flavan-3-ols and low in added sugar. Here is a simple daily pattern that gets most people close to the target without any special products.

Common mistakes

The first mistake is treating chocolate as the answer. Most chocolate on a UK shelf is high in sugar and low in flavanols, so it works against the goal. The second is reaching for a supplement. The guideline recommends food, and the COSMOS supplement result was a mixed picture rather than a green light. The third is expecting flavan-3-ols to stand in for the basics. They support blood pressure and artery function at the margin. They do not replace medication, movement, or a sensible diet.

A short note on care. Tea and cocoa carry caffeine, so people who react to caffeine or drink tea late in the day should watch their timing and total intake. If you take blood pressure or heart medication, treat flavan-3-ols as a food habit and keep taking your prescription as directed. Raise any planned supplement with your GP first. For most other people, adding tea, fruit and a little dark cocoa to the day carries little risk and fits an ordinary UK diet without fuss. Whole foods bring fibre, vitamins and other plant compounds along with the flavan-3-ols, which is a further reason the guideline favours them over any single extracted pill or powder.

Frequently asked questions

Bottom line

Flavan-3-ols are a low-risk, evidence-backed addition to a heart-smart routine. Aim for 400 to 600 mg a day from tea, whole fruit, berries and a little dark cocoa, keep the added sugar down, and hold the pattern. Flavan-3-ols support the basics of movement, sleep and a balanced plate. They do not replace them.

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