Updated 15th February 2022

Health benefits of dark chocolate and how much you should eat

The cocoa in dark chocolate is a natural source of fiber, vitamins, and minerals, and it has potential benefits for your heart, brain, gut, and overall health. 

With several times more antioxidants than green tea or red wine, dark chocolate contains substances that may help to lower blood pressure and improve cholesterol levels, brain function, and the way your body deals with insulin

Dark chocolate is particularly beneficial for your gut. It provides fuel and promotes the growth of some of the beneficial bacteria that live there. 

Sadly, not all chocolate is created equal. The percentages of cocoa in dark chocolate vary greatly, and scientific studies show that only some, in certain quantities, may have significant benefits.

Some dark chocolate also contains high levels of refined sugar and additives. 

This article looks at the potential benefits of dark chocolate and discusses what to look out for when buying dark chocolate, as well as how much to eat.

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Dark chocolate health benefits

Good quality dark chocolate offers plenty of potential health benefits. Unfortunately, chocolate is also the source of a lot of health myths, and scientists face challenges when studying it, as some of its ingredients may counteract its benefits.

Professor Tim Spector — scientific co-founder of ZOE and internationally renowned researcher at King’s College London — explains in an upcoming ZOE Science podcast that chocolate “comes from a plant that is fermented to give it great complexity, so it’s a mixture of fiber and protein, and lots of essential nutrients and defense chemicals called polyphenols.”

How exactly do these molecules in dark chocolate affect your body? Read on for our top 9 health benefits of dark chocolate.

1. Nutrients and fiber

Dark chocolate with 70% or greater cocoa has plenty of essential nutrients. It’s high in iron, magnesium, copper, and manganese, and also contains calcium, potassium, and zinc, as well as traces of vitamins A, B, E, and K. 

An average 100-gram bar of dark chocolate has around 10 grams (or 3.5 ounces) of fiber, which is beneficial for your gut health

Most dark chocolate also contains some cocoa butter, a source of the heart-healthy fat oleic acid.

It’s important to keep in mind, though, that chocolate also contains sugars and saturated fats.

2. Antioxidants 

Antioxidants are compounds found in some foods that can help prevent damage to the cells in your body. 

Polyphenols — the cocoa bean’s natural defense chemicals — are a type of antioxidant. 

Although some of these are lost during the chocolate production process, some cocoa powders have more antioxidants than so-called super fruits like acai, blueberries, and pomegranates, as well as teas and red wine

The potential antioxidant benefits of chocolate are compelling enough that one current study is looking into them on a large scale. 

Working with over 21,000 people from the United States, researchers from the study are investigating whether taking a supplement containing a concentrated dose of the antioxidants found in chocolate benefits overall health.

3. Gut health

Much like the polyphenols found in fruits, nuts, and seeds, those in dark chocolate “are like rocket fuel for your gut microbes,” says Prof. Spector. 

Cocoa is also a prebiotic, a type of fiber that your gut bacteria digest. ZOE scientists have identified 15 "good" gut bugs and 15 “bad” gut bugs associated with better and worse health measures in areas including heart and metabolic health. 

Cocoa can help your “good” bugs flourish, and our research has found that some "good" bugs particularly like dark chocolate. 

“If it’s good quality and has lots of cocoa and not so many of the other ingredients,” then “your gut bacteria generally do like chocolate,” Prof. Tim Spector says.

The ZOE-at-home test analyzes your gut microbiome in combination with your blood fat and blood sugar responses to the foods that you eat. With the ZOE program, you find out the best foods for your body and your gut bugs, including your “gut booster” and “gut suppressor” foods.

Take our free quiz to find out more. 

4. Heart health and blood pressure 

Flavanols are a type of polyphenol in chocolate, and theobromine is another compound that occurs naturally in cocoa. 

Research has linked both to improved blood vessel function, lower blood pressure, and a lower risk of heart disease in people with and without pre-existing health conditions.

While many studies support these links, scientists still recommend further research into how these substances may help support heart health.

5. Cholesterol levels

Polyphenols also benefit your cholesterol. Studies suggest they not only increase your "good” cholesterol (high-density lipoprotein, or HDL), but also reduce your "bad” cholesterol (low-density lipoprotein, or LDL) and your overall cholesterol levels. 

However, the sugar and saturated fat in dark chocolate can have a negative impact on your cholesterol if you eat too much of it. 

6. Brain function

The flavanols in dark chocolate have been linked to improved oxygen levels, nerve function, and blood flow in the brain. 

They’re also associated with increased nerve cell growth and activity in brain regions associated with learning and memory, especially the hippocampus. 

Research involving rats suggests flavanols could offer protection against a decline in brain function and related conditions like dementia and Alzheimer’s. But more studies are needed to see whether this is also true for humans. 

7. Mood

Many chocolate lovers believe in the power of chocolate as a mood enhancer, and science suggests we may be onto something.

The flavonols in dark chocolate stimulate the release of endorphins and help with mental well-being. Cocoa compounds are also involved in the production of serotonin, a neurotransmitter that boosts mood. 

However, some researchers suggest more work is needed to provide strong links between the substances in chocolate and these effects.

8. Skin protection

Antioxidants are great skin defenders, and some studies suggest that eating dark chocolate high in flavanols could help to protect your skin from UV light damage, as well as have a positive effect on wrinkles and skin elasticity

However, the potential effects of eating chocolate on skin health are not as well established as some of its other benefits, and some research links it to worse acne in people who are prone to this condition.

9. Insulin and diabetes

Scientists have looked into links between flavanols like those found in dark chocolate and their potential to decrease the risk of type 2 diabetes. 

One large-scale study found that people who ate chocolate more than once a week had a significantly lower risk of developing type 2 diabetes within 5 years, compared with people who rarely or never ate it.

The flavanols in chocolate may influence how your body deals with insulin. Some studies have found that chocolate flavanols may improve insulin production, and others suggest they could be involved in reducing insulin resistance

What percentage of dark chocolate is healthy?

The percentage of cocoa in dark chocolate is important. The more cocoa chocolate contains, the darker it is, and the greater potential health benefits it has.

As the cocoa percentage gets greater, the chocolate is also less likely to contain other ingredients. 

Dark chocolate is generally considered to be anything above 50% cocoa, but it covers a range of percentages between 50 and 90%. Some chocolate products that look dark may be high in refined sugar or dairy. 

There’s no consensus on when chocolate starts to become beneficial for your diet, but Prof. Spector recommends dark chocolate that is at least 70% cocoa. 

“If you go for very high cocoa content, then you’re less likely to get anything that’s unhealthy. Pick something with the minimum number of ingredients on the label, and then you know you’re going to get something that is really natural with very little taken away.” — Prof. Tim Spector

Flavored or lower cocoa chocolate not only has more sugar, but it may also contain artificial sweeteners as well as emulsifiers to bind it together. 

Prof. Spector warns that these extra ingredients “are bad for your gut microbes and will actually counteract any of the benefits” of the chocolate. 

Try to choose organic dark chocolate to ensure that any added flavorings are less processed.

Other factors can impact the potential health benefits of dark chocolate. Treating chocolate with alkali (known as Dutch-processing) can reduce the cocoa’s naturally bitter flavor but also significantly decreases its antioxidant levels

Likewise, the darker the chocolate, the more caffeine it has, which may be an issue if you’re sensitive to caffeine. 

How much dark chocolate should you eat each day?

There are no official recommendations for how much dark chocolate you should eat to get health benefits. The key is moderation. 

Spencer Hyman, chocolate expert and founder of ethical craft chocolate company Cocoa Runners, recommends a “less is more” approach. 

“Try and train yourself to savor rather than to scarf,” he explains in an upcoming ZOE Science Podcast. “It’s much better to have [a little bit of dark chocolate] than scarf some low-fat vanilla yogurt, which has actually got seven times the amount of sugar in it than a dark chocolate bar would have.”

In scientific studies, participants usually consume small or moderate amounts of chocolate. 

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One review of studies looking at the effects of eating dark chocolate found that researchers gave participants between 20 grams (0.7 ounces) and 100 grams (3.5 ounces) each day. 

Another more recent review found that the majority of studies used a maximum of 20 grams per person per day. 

Opt for dark chocolate with higher cocoa percentages and lower levels of sugar, fat, or artificial ingredients, and eat it in moderation. 

Exactly when you eat it could be important, too. Studies suggest that eating a small amount of dark chocolate in the morning or evening may help stabilize your blood sugar levels by limiting your sweet cravings.

As Hyman says, good dark chocolate is “a great way of satisfying your cravings for sweetness at the end of a meal without having too much of it.”


Dark chocolate is definitely a treat for your tastebuds. In moderate quantities and with high cocoa percentages, it may also be good for your health. 

Aim for chocolate that is at least 70% cocoa. This contains more natural fiber, minerals, vitamins, and antioxidants, and fewer other ingredients like refined sugar and additives, which are present in lower percentage chocolate. 

There is evidence that the nutrients and antioxidants in cocoa — particularly flavanols — may help:

  • boost beneficial gut bacteria

  • improve cardiovascular health, cholesterol levels, mood, and brain function

  • balance insulin production and sensitivity

  • promote healthier skin

However, some scientists believe further research is needed to back up some of these claims and to work out how much chocolate you need to eat to experience potential benefits.   

Good quality chocolate with a high cocoa percentage can be part of a healthy, balanced diet, especially if you learn to savor it and eat it in moderation. 

An ounce or two of dark chocolate after a meal is a great way to satisfy a sweet craving without eating too much refined sugar or saturated fat.

The best way to understand what’s good for your body is to learn more about your individual responses to different foods. 

The ZOE program gives you personalized scores for hundreds of foods, based on your unique collection of gut bugs and your blood sugar and blood fat responses after meals. This allows you to truly eat the best foods for your body.

Take a free quiz to find out more. 


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