National chocolate week – The benefits of eating dark chocolate

Many of us can relate to the stress easing benefits that a square of our favourite chocolate can bring. For some it’s a guilty pleasure, for others, chocolate is that treat at the end of a hard week and we’re sure many would say that it’s the ultimate comfort food.

We’re on the topic because last week the UK celebrated national chocolate week in a number of creative ways, before culminating in the Chocolate Week Festival in London over the weekend.

Whilst we didn’t go above and beyond to recognise the week, we thought we would take the opportunity to reflect on the beneficial aspects of eating dark chocolate – that is 70% or more cocoa solids.

What is chocolate?

The cocoa bean is the main component of cocoa and chocolate. The term cocoa or cacao refers to the natural product, whereas chocolate is a processed food containing sugar, fat, other additives and sometimes milk in addition to cocoa.

The cocoa tree, Theobroma cacao, is cultivated for its seeds, known as cacao beans or cocoa beans.  Raw cacao powder is made by cold-pressing unroasted cocoa beans. The process keeps the living enzymes in the cocoa and removes the fat (cacao butter). Cacao is naturally high in antioxidants. Cocoa looks the same but it’s not; cocoa powder is raw cacao that’s been roasted at high temperatures. Sadly, roasting changes the molecular structure of the cacao bean, reducing the enzyme content and lowering the overall nutritional value.

The fat predominantly found in dark chocolate is cocoa butter which contains approximately 33% oleic acid, 25% palmitic acid, and 33% stearic acid. Oleic acid is a monounsaturated fatty acid that has a positive effect on lipid levels. Stearic acid and palmitic acid are saturated fatty acids.

Cocoa contains minerals such as potassium, phosphorus, copper, iron, zinc, and magnesium. Chocolate also contains valeric acid which acts as a stress reducer despite the presence of the stimulants caffeine and theobromine in the chocolate.

There are centuries of documented uses of chocolate in medicine and diet in ancient cultures dating back to the South American Incas and Aztecs. And it is believed to be Christopher Columbus who was the first to bring cocoa beans (and thus chocolate) to Europe.

Flavanols and methylxanthines

One of the main ingredients in chocolate that contributes to its health effects is the phytonutrient known as cocoa flavanols. The beneficial effects of the flavanols have been attributed to their antioxidant effects, regulation of gene expression and signalling pathways and changes they bring about in cell membrane and receptor functions.

Dark chocolate has a flavanol content of 460-610 mg/L; this compares with green tea that has a content of 100 – 800 or an apricot 100 – 250 mg/L.

The other significant bioactive ingredients are methylxanthines – caffeine and theobromine. These are found in cacao, coffee and tea. Methylxanthines have a number of mechanisms of action, the most significant is thought to be their action as antagonists of adenosine receptors in the central nervous system. Adenosine receptors have multiple physiological roles including controlling the release of neurotransmitters such as dopamine and glutamate. Methylxanthines are nervous system stimulants, diuretics and smooth muscle relaxants, they thus enhance arousal, mood, and concentration levels.

Milk chocolate or dark chocolate?

When talking about chocolate in relation to health it is important to be clear what we are talking about. Milk chocolate is a ‘sweet’ and cannot be considered a healthy food due to its high sugar content and sometimes the inclusion of other undesirable ingredients. To compare the sugar content of different types of chocolate, in a 40 g serving:

  • 70% dark chocolate contains 3 teaspoons of sugar (4 g sugar = 1 teaspoon)
  • 85% contains 1.5 teaspoons of sugar
  • Milk chocolate contains around 5.5 teaspoons of sugar

Flavanols are more prevalent in dark chocolate than in milk chocolate. The more ‘non-fat’ cocoa solids a chocolate product contains, the more antioxidant cocoa flavanols it should contain. Most chocolate products have other types of fat such as milk added which will vastly dissipate the beneficial cocoa flavanol content. Such products are also more likely to have appreciable levels of saturated and possibly even trans fats, which are to be avoided. As well as being higher in sugar these products are also likely to be higher in calories (and additives) and hence the risks (with excess consumption) for weight gain, diabetes and heart health issues.

The benefits of dark chocolate

Whilst raw cacao undoubtedly offers the best health benefits, research has shown benefits from consuming dark chocolate (i.e. 70% plus), for example:

Chocolate and inflammation

Inflammation plays a key role in the onset and development of most chronic diseases. A study comparing individuals who did not consume chocolate for one year with individuals who regularly consumed dark chocolate showed a significant association between moderate levels of cocoa ingestion and inflammation. Serum CRP levels were significantly lower in subjects consuming 20g cocoa every 3 days compared to subjects with either no or greater cocoa consumption.

Chocolate and stress

Dark chocolate can have a positive impact on cortisol levels, one of the hormones released in response to stress.  Chronically elevated cortisol levels can lead to disrupted sleep, weight gain, raised blood sugar levels, food cravings, suppressed immunity as well as long term health issues.

A Swiss study found that; “the daily consumption of dark chocolate resulted in a significant modification of the metabolism of healthy and free living human volunteers with potential long-term consequences on human health within only 2 weeks treatment,” the researchers wrote, “this was observable through the reduction of levels of stress-associated hormones and normalization of the systemic stress metabolic signatures.”

Chocolate and cardiovascular disease

Polyphenols that are found in cocoa have been shown to play a role in reducing cardiovascular stress through the inhibition of LDL cholesterol oxidation; it is the oxidation of LDL which is critical in the onset of atherosclerotic diseases. These compounds also increase the vasodilation of blood vessels to promote circulation. Cocoa flavanols thus have an EFSA permitted health claim “Cocoa flavanols help maintain the elasticity of blood vessels, which contributes to normal blood flow.”

A study in elderly patients has shown that cocoa intake was associated with reduced blood pressure and total cardiovascular mortality. A case control study in Italy reported an inverse relationship between chocolate consumption and heart attack.

Chocolate and the gut

The bacteria in our gut ferments the polyphenols and fibre in cocoa. Chocolate stimulates the growth of beneficial bacteria in the gut – such as Bifidobacteria and Lactobacillus spp, which break down the fibre in cocoa producing short chain fatty acids such as butyric, propionic and acetic acids which promote satiety and create anti-inflammatory compounds, which improve blood vessel function. Cacao and/or chocolate modifies intestinal flora in the same way that prebiotics and probiotics do.

Chocolate and weight loss

Studies have shown eating a small amount of chocolate before a meal triggers satiety signals in the brain subsequently leading to reduced consumption.

In an animal study, cocoa consumption led to a significant reduction in total body weight and changes in other parameters such as white adipose tissue weight and serum triglycerides. DNA analysis on liver and mesenteric fat tissue samples showed a reduction in expression of various genes associated with fatty acid transport and synthesis in the liver, and increased expression of genes associated with thermogenesis.

Chocolate and diabetes

In animal models and in a limited number of human studies, flavanols and methylxanthines have been found to have positive effects on glucose homeostasis through a number of mechanisms – including attenuating postprandial glycemic response and improving insulin sensitivity.

Chocolate and cognitive function

Flavanols accumulate in the brain regions involved in learning and memory, especially the hippocampus where they may have beneficial actions via neuroprotection and via improved blood flow. Animal intervention and a few human observation and intervention studies have reported protective effects in relation to age and disease related cognitive decline.

A 2016 study reported increased chocolate consumption was associated with better performance on a range of memory and cognitive tests.

A research team in Mexico, led by Dr Lilian Calderón-Garcidueñas, is evaluating the use of cocoa to protect urban children from the effects of particulate matter and ozone pollution. Extensive neuroinflammation, oxidative stress, and hallmarks of Alzheimer disease pathology are present in the brains of Mexico City children and young adults with chronic year-long exposures to high levels of ozone and particulate matter.

Negative impacts of cocoa

We’ve covered the benefits that a little dark chocolate can bring in moderation, but what about the adverse effects? For some, cocoa can trigger a migraine; this may be due to its containing the amino acid tyramine, a well-known migraine trigger (also found in some other foods). Also, the caffeine in chocolate may be an issue for people sensitive to it – in particular those with difficulty sleeping. Dark chocolate contains between 18 – 70 mg of caffeine per 100g – a cup of instant coffee contains around 80mg. And of course, overconsumption of any type of chocolate may lead to weight gain.

In summary, it is clear from the body of research that dark chocolate and raw cacao do indeed carry some truly significant health benefits. The bitter taste masks the sweet benefits that a 70% or 85% cocoa solids bar can bring when eaten in moderation. As we mentioned earlier; dark chocolate still contains added sugars so limit yourself to a 20 – 40g portion per day.


Crichton G E (et al) 2016 – Chocolate intake is associated with better cognitive function: The Maine-Syracuse Longitudinal Study, Appetite, 1;100:126-32

Franco R et al (2013) – Health benefits of methylxanthines in cacao and chocolate. Nutrients, 5(10, 4159-4173

Latif R (2013) – Chocolate / cocoa and human health: a review, Neth J Med, 71(2):63-71(2)

Martin F P J et al (2009) – Metabolic Effects of Dark Chocolate Consumption on Energy, Gut Microbiota, and Stress-Related Metabolism in Free-Living Subjects. Journal of Proteome Research, 8, 12, 5568-5579

Senturk T and Gunay S (2014) – The mysterious light of dark chocolate. Arch Turk Soc Cardiol, 43, 2, 199-207

Sokolov A N et al (2013) – Chocolate and the brain: neurobiological impact of cocoa flavanols on cognition and behaviour. Neuroscience and Biobehavioural Reviews, 2445-2453

Related Cytoplan blogs

Stress and cortisol

Indulging in resveratrol and cocoa flavanols for Christmas?

Nutrient support for cardiovascular health

Could the answer to obesity lie in the gut?

Cholesterol confusion

If you have any questions regarding the topics that have been raised, or any other health matters please do contact me (Amanda) by phone or email at any time., 01684 310099

Amanda Williams and the Cytoplan Editorial Team: Joanna Doverman, Clare Daley and Joseph Forsyth.


8 thoughts on “National chocolate week – The benefits of eating dark chocolate

  1. loved this in-depth article. I was recommended to have two small squares of dark low-sugar chocolate daily by a nutritionist some years ago and have never looked back! I would like to recommend Vivani 92% for those serious dark chocolate lovers. Even 70% dark chocolate now tastes too sweet.

  2. Hello, thank you for your post. I have bought a bag of cocoa beans and was very excited. Then my friend saw it and said that it was not as healthy as we thought- notice, no animal would eat cocoa bean in nature. There are lots of stories on internet of people getting bad reactions from eating cocoa, and feeling very unwell.

    Only a small section of your article mentions about bad side of eating cocoa, could you please investigate further?

    1. Hello Basia,

      Thank you for your comment on our blog. Interestingly chocolate is toxic to dogs and cats as they do not have the enzymes to metabolise the theobromine – so perhaps this is why animals would not eat a cocoa bean. Chocolate is quite a potent substance and, as you say, some people may experience a negative reaction to it; in which case it is best avoided. This may be due to the methylxanthines, biogenic amines or other components. I have not been able to find any large scale studies so cannot say how common reactions to chocolate are but as you mention there are anecdotal reports on the internet.

      If you have any further queries please don’t hesitate to contact me,

      All the best,

  3. Good article – except for the slur on saturated fats. Saturated fats, including animal fats, have now been proven to be beneficial contrary to the years and years of advice to the contrary.

    1. Dear Molly

      Thank you for your comment on our blog. We agree the evidence on saturated fat has changed and we have not discussed saturated fat in this blog or suggested that this would be a reason to avoid eating chocolate. Eating a high fat diet alongside a diet high in carbohydrate is not recommended, but healthy fats in the diet, especially from olive oil, nuts/seeds and oily fish are important for overall health. With regard to saturated fats these can be made in the body, but some types have been shown to have particular benefits eg short chain and medium chain fatty acids (found in butter and coconut oil respectively).

      All the best

  4. Sadly for me eating 2 squares of chocolate with 3 Brazil nuts (Selenium) did not work. When I eat chocolate I come out in spots!!!!!!!!! Fortunately I am no a great chocolate fan.

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