A creamy mug of cocoa is not generally considered good for us, but new research suggests the indulgent winter warmer could temporarily boost intelligence.
Cocoa is rich in antioxidants called flavanols, which have long been known to have a positive effect on the heart.
To better understand how the nutrients affect the brain, scientists from the University of Birmingham analysed 18 healthy men after they were exposed to raised – but still safe – carbon dioxide levels, which reduces circulation to the vital organ.
The men were then asked to complete complex cognitive tests. Those who drank flavanol-rich cocoa beforehand performed significantly better and around 11% faster.
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“We used cocoa in our experiment, but flavanols are extremely common in a wide range of fruit and vegetables,” said lead author Dr Catarina Rendeiro.
Grapes, apples, tea and berries are also particularly rich in the nutrients, which have been shown to help lower blood pressure, improve blood flow, prevent clots and fight cell damage.
“By better understanding the cognitive benefits of eating these food groups, as well as the wider cardiovascular benefits, we can offer improved guidance to people about how to make the most of their dietary choices,” said Dr Rendeiro.
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The scientists looked at 18 men aged 18 to 40. As part of a standard experiment to challenge the brain’s circulation, the men breathed in 5% carbon dioxide – around 100 times the gas’ air concentration.
This produces an effect called hypercapnia, a build-up of carbon dioxide in the bloodstream. Feeling disorientated and unfocused are mild side effects of the condition.
A technique called non-invasive near-infrared spectroscopy used light to reveal how the men’s blood oxygen levels changed.
After breathing in the elevated carbon dioxide, the men completed progressively more difficult cognitive assessments.
The experiment was carried out twice. On one occasion, the men drank flavanol-rich cocoa before having their brain circulation challenged. It is unclear what other ingredients, like sugar, the drink contained.
Results, published in the journal Scientific Reports, revealed the men who consumed the flavanol-rich cocoa had up to three times higher blood oxygen levels than those who went without.
When it came to the cognitive tests, the men who drank the cocoa performed significantly better and faster on the complex tests.
“Our results showed a clear benefit for the participants taking the flavanol-enriched drink, but only when the task became sufficiently complicated,” said Dr Rendeiro.
“We can link this with our results on improved blood oxygenation.
“If you’re being challenged more, your brain needs improved blood oxygen levels to manage that challenge.
“It also further suggests flavanols might be particularly beneficial during cognitively demanding tasks.”
A subgroup of the men who had high levels of oxygen in their brain at the start did not benefit at all from the flavanol-rich drink.
“This may indicate some individuals, that perhaps are already very fit, have little room for further improvement,” said Dr Rendeiro.
“The small group of participants who did not react to the flavanol gives us additional evidence to confirm the link between increased brain blood oxygenation and cognitive ability.”
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