The late Dr Michael Mosley, creator of the Fast 800 diet and host of the BBC's Just One Thing podcast, said that dark chocolate could lower blood pressure, satisfy cravings for a sweet treat, improve cardiovascular health and boost brain health.
He explained that some studies suggest “a couple of squares of the really dark stuff may be good for you” because it is “full of flavonoids – a nutrient found in certain plants – which may explain why eating dark chocolate is so much healthier than the milky stuff.”
Why Dark Chocolate Is Healthier
The BBC expert explained that studies have suggested the key element in cocoa is a class of chemical compounds called flavonoids, present in many plant foods such as strawberries, tea, blueberries, apples and onions. The bitter seeds of the cacao tree are one of the richest known sources of flavonoids, but you don't have to eat those seeds to get the benefits – just chocolate with high cocoa content.
Urging people to swap their usual milk or white chocolate bars for something closer to 85%, he noted that the buzz about cocoa's potential health benefits came from population studies of the Guna people, who live off the coast of Panama. Researchers found they tended to live long lives and didn't see their blood pressure rise with age, with one explanation being their high intake of unsweetened cocoa – reportedly as much as five cups a day.
What the Studies Show
For fans of white and milk chocolate, the news isn't as good. Mosley said: “Sadly, there are no flavonoids in white chocolate and very little in milk chocolate. The highest amount is found in unprocessed dark chocolate.”
He cited a recent study done in Portugal, where 30 healthy volunteers ate 20 grams a day for a month, finding that doing so reduced blood pressure by a small but significant amount. Other studies also suggested benefits: 90 older adults in Italy who consumed a special high-flavonoid cocoa drink saw improvements in blood pressure, insulin resistance and cognition. A brain imaging study in young adults found that those who drank high-flavonoid drinks completed certain cognitive tests more efficiently, with better oxygenation and improved blood flow.
How Much Should You Eat?
During the podcast, Mosley spoke to Professor Aedin Cassidy at Queen's University Belfast, whose research found that eating dark chocolate high in flavonoids every day could improve the elasticity of blood vessels, insulin sensitivity and cholesterol levels in women with Type 2 Diabetes. He explained that just two squares of dark chocolate are enough to see positive effects, and that sticking to this is important.
The BBC blog, based on his podcast, stressed that in large amounts, chocolate can raise blood sugars and could lead to weight gain, both of which can increase rather than reduce your risk of cardiovascular disease. The best thing to do is swap out your usual sugary snack for something much darker, getting the benefits of cutting down on fat and sugar plus the flavonoid compounds – “the double whammy effect.”
What the British Heart Foundation Says
In a health update, the British Heart Foundation (BHF) noted that a 2025 review of human trials found that flavanol-containing foods (including cocoa, tea and some fruits) were seen to potentially reduce the risk of heart and circulatory diseases. It explained: “Although these studies are promising, commercial chocolate usually contains much lower levels of flavanols than the cocoa bean products used in scientific studies. And while cocoa solids are a natural source of flavanols, a lot are lost during the process of making chocolate.”
The BHF also explained the differences: dark chocolate is made from cocoa solids (35 to 90 per cent cocoa solids), cocoa butter and sugar; milk chocolate is made from cocoa solids (generally less than 35 per cent), cocoa butter, sugar and milk powder, and often contains more sugar than dark; white chocolate is technically not a ‘real’ chocolate as it contains no cocoa solids, only cocoa butter, sugar and milk powder.
Experts at the BHF note that dark chocolate generally has higher levels of flavanols than milk chocolate, and these compounds have been associated with heart-health benefits, including helping to reduce high blood pressure. However, because flavanol levels aren't clearly stated and can vary widely between products, it's difficult to know how much you're actually getting. It adds: “We do know that dark chocolate, like other types of chocolate, is also high in fat, saturated fat, sugar and calories, and eating too much may contribute to high cholesterol and weight gain.”
The BHF concludes: “There is no harm in eating small amounts of dark chocolate a few times a week as part of a balanced diet. Think of dark chocolate as a treat that may be beneficial to your health, rather than a ‘health food’ you should eat lots of.” Prior to his passing in 2024, Dr Mosley inspired millions to transform their wellbeing, championing intermittent fasting and developing the 5:2 diet.
