Is Dark Chocolate Actually Healthy? What the Heart Science Says, and Why We Don't Just Call It Green

Dark chocolate is the rare treat that turns up wearing a lab coat. Put "85%" on the front of a bar and it stops feeling like confectionery and starts feeling like something you are doing for your health. The antioxidant story is everywhere, and it is flattering, because it lets a pleasure double as a virtue. So it is worth asking the plain question: is dark chocolate actually good for your heart, and if there is something to it, why does our app refuse to wave it straight through as a green?

What the science actually shows

The compounds everyone is reaching for are cocoa flavanols, a family of plant antioxidants, the most studied of which is epicatechin. In short studies they do appear to do something real. They prompt the lining of your blood vessels to release more nitric oxide, which relaxes and widens them, and that turns up as better blood-vessel function and small reductions in blood pressure across many trials.

The big test was COSMOS, published in 2022. Around 21,000 older adults took either a cocoa flavanol supplement or a placebo for roughly three and a half years. The result is genuinely mixed, and it is worth being honest about rather than cherry-picking. The main goal, cutting total cardiovascular events, was not statistically significant, about a 10% reduction that could have been down to chance. A secondary measure, death from cardiovascular disease, came out 27% lower, which is a promising signal, but a secondary one that needs confirming. Encouraging, in other words, not settled.

The catch the packaging leaves out

Here is the part the "dark chocolate is good for you" headlines tend to skip, and it is the part that matters most.

COSMOS gave people a standardised flavanol supplement in a capsule. Not a chocolate bar. That distinction does more work than it looks, for two reasons.

First, the cocoa percentage on the front of a bar tells you almost nothing about how much flavanol is inside. Flavanols are fragile, and ordinary chocolate-making knocks them down: fermentation, roasting, and above all alkalisation, the "Dutch processing" or "processed with alkali" you sometimes spot in the small print, which is used to mellow bitterness and deepen colour and which destroys the large majority of the flavanols. Natural cocoa can carry several times the flavanols of a heavily processed one. Two bars both stamped 70% can deliver wildly different doses, and nothing on the label lets you tell which is which.

Second, even where the flavanols survive, you would have to eat an unrealistic amount of chocolate, and all the sugar, fat and calories riding along with it, to reach the doses used in the research. This is not a fringe opinion. The cocoa company that funded the COSMOS trial, and which sells flavanol supplements, states plainly that most chocolate is too low in flavanols and too calorie-dense to be treated as anything but a treat. When the people with the strongest commercial reason to call chocolate a health food decline to do so, that is worth noticing.

So, is it healthy?

The honest answer is that dark chocolate is a better treat than milk chocolate, and a genuinely lovely one, but it is a treat, not a health food. The move from milk to dark is a real improvement, mostly because the sugar falls away as the cocoa climbs, which is the whole point of the cocoa ladder we wrote about in retraining your palate. What it is not is a heart supplement you should be eating for your arteries. If what you are actually after is the flavanol dose the studies used, that is the job of standardised cocoa extract or natural, non-alkalised cocoa, not a bar of the dark stuff from the corner shop.

Why we don't just call it green

This is exactly the kind of product where a scoring system shows its hand, so it is worth being open about ours.

It would be easy, and good marketing, to slap a green on dark chocolate and lean on the antioxidant halo. We do not, and the reason is the whole point of how MyFoodFit scores. The engine scores the food that is actually in front of you, against your profile: the sugar, the saturated fat, the energy density, what the thing is and how much of it you would eat. It does not hand out credit for a health story it cannot verify. A 90% bar genuinely scores better than a milk chocolate one, because it carries far less sugar, and the app reflects that. But "better than milk chocolate" is not the same as "green", and it will not be promoted to green on the strength of flavanols the label does not even confirm are there.

That is a deliberate line. We score against the mainstream clinical guidance you would recognise from the NHS, the British Heart Foundation and the British Dietetic Association, rather than whichever wellness narrative is having a moment. Dark chocolate as an occasional pleasure is entirely reasonable. Dark chocolate reclassified as a health food on the back of an antioxidant it may or may not contain is the bit we will not do. A score you can trust has to be willing to give an honest amber to something people would much rather hear is green.

Enjoy it as what it is

So enjoy your dark chocolate. If you have worked your way up to the high-percentage stuff, you have quietly stripped a lot of sugar out of one of life's nicer habits, and that is worth more than any antioxidant headline. Eat it as the treat it is. And if you genuinely want the heart-science dose, get it from something built to deliver it.

None of this is medical advice. If you are managing your blood pressure or your heart health, the place to start is the guidance from your GP or a registered dietitian, not a chocolate bar.