Dark chocolate health benefits explained - and exactly how much you should eat

We've all heard that an apple a day keeps the doctor away, but research increasingly shows that another daily food habit may have myriad health benefits - eating a square or two of dark chocolate. Cocoa is a rich source of flavanols, a compound in the flavonoid group with antioxidant and anti-inflammatory effects. A recent study from the University of Surrey found that people who consumed more flavanols from cocoa - as well other sources including tea, apples and grapes - saw greater reductions in blood pressure over time, particularly if it was elevated to begin with.

Published in the European Journal of Preventive Cardiology, the research analysed data from 145 previous studies. The blood pressure-lowering effects identified were comparable to that seen with some prescription medications. Another study in the British Medical Journal, involving almost 19,000 people, found those who ate five or more servings of dark chocolate per week were 21% less likely to be diagnosed with type 2 diabetes, compared with those who never or rarely consumed it.

Other research has identified a possible link with reduced cholesterol and stress levels, and reduced inflammation throughout the body. "Dark chocolate is also rich in polyphenols, a natural compound found largely in fruit and vegetables, which can help to promote good bacteria in the gut.

Gabrielle Newman, a nutritionist and recipe developer for The Fast 800 intermittent fasting plan, says: "A small daily dose of high-quality dark chocolate can offer surprising benefits.

"The flavonoids in cocoa are associated with improved blood flow to the brain, enhanced memory, and even reduced mental fatigue. Some studies suggest that regular consumption of high-flavonoid cocoa can support cognitive health as we age.

"Additionally, dark chocolate contains compounds that can elevate mood by boosting serotonin and endorphin levels."

Chocolatier Tracy Deacon, head of new product development at Cartwright & Butler, similarly believes dark chocolate "possesses many potential health benefits" when eaten in moderation.

"The benefits of dark chocolate appear never-ending for boosting mental well-being, as it helps to release endorphins and boost serotonin and in turn, create a positive mood," she says.

"It has been found that dark chocolate may help to quell a sweet tooth after a meal which will have a positive impact on our physical health as well as mental."

Of course, not all chocolate is created equal. So which should you choose?

Bitter is better

Ryan James, health and wellbeing advisor at Vitality, says sticking with dark chocolate is the best option for health. He explains: "Chocolate manufacturers don't include details of flavanol - the plant-based antioxidant - content on their labels, so it can be difficult to know exactly how much is contained in a bar.

"But the rule of thumb is 20g of dark chocolate (60% cocoa solids) contains 34mg of flavanols, 20g of milk chocolate contains 14mg of flavanols and 20g of white chocolate contains no flavanols.

"To make things even trickier, milk and white chocolate also contain larger amounts of sugar and milk, meaning they contain more calories and unhealthy fats, compared to dark chocolate."

Gabrielle's advice is to opt for dark chocolate with at least 70% cocoa content "for the most benefit and the least sugar". "In general, the more bitter the chocolate, the better it is for you," she explains.

"For most people's palates, that bitter flavour indicates a higher cocoa content and less added sugar. Dark chocolate (typically 70% cocoa or higher) contains more flavonoids, which are plant compounds shown to have antioxidant and anti-inflammatory properties.

"These flavonoids have been linked to better heart health, improved blood flow, and even enhanced cognitive function.

Milk chocolate, by contrast, contains more sugar, milk solids, and fat, and less cocoa, so these beneficial compounds are diluted."

If you struggle with the bitter taste of high cocoa chocolate, Gabrielle recommends making a slow transition.

"Start by choosing chocolate with a slightly higher cocoa content than you're used to - for example, move from milk chocolate which is often around 30% cocoa to one containing 50% cocoa, and gradually work your way up to 70% or more.

"Pairing dark chocolate with some fruit or nuts can soften the bitterness and make the flavour more enjoyable. Over time, your taste buds will adapt, and what once seemed bitter can start to taste rich and even sweet."

Nutritionist Kate Cook, who works with high-quality cocoa brand Food Thoughts, agrees that varieties with at least 70% cocoa are best.

"The higher the cocoa content, the more likely it is to contain the good stuff, and the less sugar and unnecessary additives it will have," she explains.

"A small amount goes a long way. Around 50g of dark chocolate can give you around 28% of your daily magnesium needs and 33% of your iron, plus other helpful minerals. So if you enjoy it in moderation, it can be a tasty and nutritious treat.

"Look for chocolate that is high in cocoa content, has minimal added sugar, and ideally is organic, meaning it's produced without harmful chemicals, and may have a more intense nutrient profile. Organic is something I personally prioritise, both for health and environmental reasons."

However, Tracy cautions that a higher cocoa content "does not necessarily mean the better quality the chocolate - it is all about the quality ingredients that go into the product".

"As a chocolatier I love to opt for dark chocolate for its intense fruity notes and antioxidant benefits," she adds. "I like to mix this with ingredients such as ginger, which is good for digestion and helps boost the immune system.

"The addition of nuts also helps to add nutritional value as well as an extra burst of flavour for a luxurious taste sensation."

Avoid overindulging

Sadly, eating copious amounts of chocolate will not lead to limitless health benefits. Gabrielle recommends eating at most two squares per day because "this provides beneficial flavonoids without excessive calories or sugar".

"Going overboard, even with dark chocolate, can lead to weight gain and offset the health benefits. It's best to treat it as a small, satisfying part of your daily or weekly routine rather than mindless indulgence."

Tracy also suggests choosing a dark chocolate with a high percentage of cocoa solids, and eating it in small portions of around 20g - or two squares -as a treat. "As with many foods it is all about moderation to get that feel-good fix," she says.