Dark chocolate: what it really offers, how much to eat and how to choose it

What does dark chocolate offer, depending on its cocoa percentage?

The percentage on the label indicates how much of the product comes from cocoa. In dark chocolate, almost everything else is sugar. This is why a higher percentage means less sugar and more fibre, although it also contains slightly more fat [1].

Per 100 g	Energy	Fat	Sugars	Fibre
Milk chocolate	535 kcal	29.7 g	51.5 g	3.4 g
Dark chocolate, 60–69%	579 kcal	38.3 g	36.7 g	8 g
Dark chocolate, 70–85%	598 kcal	42.6 g	24 g	10.9 g
Unsweetened pure cocoa powder	228 kcal	13.7 g	1.75 g	37 g

Switching from milk chocolate to chocolate with 70–85% cocoa reduces the sugar content to less than half [1]. The energy content barely changes because the cocoa fat takes the place of the sugar. Much of this fat is saturated: about 24.5 g per 100 g in the 70–85% chocolate [1].

In practical terms, a 10 g square of 70–85% dark chocolate provides about 60 kcal and 2.4 g of sugars [1].

What does the evidence say about flavanols and cardiovascular health?

Cocoa flavanols are plant compounds belonging to the polyphenol family. The European Food Safety Authority (EFSA) concluded that they help maintain the ability of blood vessels to dilate, which contributes to normal blood flow [2].

The amount matters. The effect is obtained with 200 mg of flavanols a day, which can be provided by 2.5 g of cocoa powder or 10 g of dark chocolate rich in flavanols [2]. Only products that guarantee those 200 mg a day may make this claim on their packaging [3].

Ordinary dark chocolate does not state how many flavanols it contains, so you cannot tell whether it provides that amount. There is also no authorised claim stating that chocolate prevents blood clots or heart attacks, or lowers cholesterol. If your doctor has prescribed treatment for blood pressure or cholesterol, chocolate is not a substitute.

How much dark chocolate is reasonable?

In consultations, we usually suggest one or two squares a day, around 10 to 20 g, of dark chocolate with at least 70% cocoa. This is our practical guideline, intended to let you enjoy it without displacing fruit, nuts or yoghurt.

Sugar is another consideration. The World Health Organization recommends keeping free sugars below 10% of daily energy intake [4]. 5% is a desirable target [4]. For a diet of around 2,000 kcal, the 10% limit is equivalent to about 50 g a day [4]. Two squares of 70–85% chocolate provide around 5 g, while the same amount of milk chocolate contains about 10 g [1].

Chocolate also contains caffeine and theobromine, two mild stimulants. Each 100 g of 70–85% chocolate contains around 80 mg of caffeine, so a couple of squares provide about 16 mg [1]. During pregnancy, caffeine from all sources should not exceed 200 mg a day [5].

Pure cocoa powder versus sweetened cocoa

Unsweetened pure cocoa powder is the form of cocoa with the least sugar—1.75 g per 100 g—and plenty of fibre, at 37 g [1]. A teaspoon adds a chocolate flavour to porridge, yoghurt or a homemade cake.

Sweetened cocoa drink powder is a different product. If sugar appears before cocoa in the ingredients list, the container contains more sugar than cocoa, because ingredients are always listed from highest to lowest quantity [6]. The sugars line per 100 g tells you exactly how much [6].

How to read a chocolate label

For a product to be called chocolate, it must contain at least 35% cocoa under European regulations [7]. Above that minimum, the percentage is your first clue.

• Look for 70% cocoa or more. Above this level, sugar makes up less than a third of the weight [1].
• Check the first ingredient. In dark chocolate with a high cocoa content, cocoa mass comes before sugar [6].
• Look at the sugars per 100 g. This lets you compare two bars with the same cocoa percentage [6].
• Check the fats. If it contains vegetable fats other than cocoa butter, this must be stated [7].
• If it says “sugar-free”, keep reading. Check what it contains instead and how many kcal it provides per 100 g.

Chocolate and migraine, reflux or acne

These are the three health questions people ask most often about chocolate. There is no single answer to any of them, and in each case the decision should be made with your doctor.

Migraine

Chocolate is the food most often cited as a trigger for migraine. However, a review of published studies found insufficient evidence to confirm this [8]. If you suspect it affects you, note what you eat before each attack and discuss it at your medical appointment.

Reflux

In laboratory studies, chocolate relaxes the lower oesophageal sphincter, the valve that closes the passage between the oesophagus and the stomach [9]. Even so, few studies show that avoiding it improves reflux. If you suspect it makes your symptoms worse, stop eating it for one or two weeks and then try it again [9].

Acne

A systematic review found an association between diets with a high glycaemic load—that is, diets containing many foods that raise blood glucose quickly—and a modest effect on acne [10]. The review includes chocolate in this group because of its sugar content and, often, its milk content [10]. The guide to the glycaemic index explains the idea in more detail.

Questions about chocolate that come up in consultations

“If it’s 85%, I can eat more.” It contains less sugar and almost the same amount of energy as 70% chocolate—about 600 kcal per 100 g [1]. The reasonable serving is the same.

“Can I eat it while I’m losing weight?” Yes. What matters is the overall pattern across the week, and one or two squares can fit into a weight-loss plan. The same approach applies to other sweets, such as quince paste: have a small portion from time to time.

“When I open a bar, I finish it.” This is common and can be addressed. If eating chocolate is linked to feeling out of control or to guilt that lingers, we can work on it with our team of dietitians specialising in eating behaviour.

“It’s an antioxidant, so it’s healthy in any amount.” The fact that a food contains polyphenols does not make it a remedy, and chocolate is still very energy-dense [1].