Cocoa is good for you – but that does not mean you should eat more chocolate, say scientists.
Bioactive ingredients that appear to be contained in cocoa were found to sharply reverse age-related memory decline in a group of volunteers.
The compounds, called flavanols, were taken in a specially prepared cocoa drink, according to an experiment published by the journal Nature Neuroscience.
For three months, 37 healthy volunteers between the ages of 50 and 69 took a daily drink containing either a high dose of flavanols – 900 milligrams – or a low dose – 10mg.
Researchers carried out brain imaging, measuring blood volume in a key part of the hippocampus called the dentate gyrus – a region of the brain that deals with memory formation, the performance of which typically declines as we age.
Researchers also carried out memory tests before and after the volunteers began taking the drink.
The high-flavanol group notched up major memory improvements and an increase in blood flow to the dentate gyrus.
“If a participant had the memory of a typical 60-year-old at the beginning of the study, after three months that person on average had the memory of a typical 30- or 40-year-old,” says Scott Small, a professor of neurology at Columbia University Medical Center in New York.
More work, in a bigger test group, is needed to verify these early findings, he adds.
Flavonols have generated great interest among scientists. They dangle the tantalising possibility of tackling age-related memory loss in the world’s fast-growing population – the elderly – without using drugs.
The compounds exist in grapes, blueberries and other fruit, as well as in certain vegetables and teas, but the type of flavanol and the amount vary widely depending on the source.
Previous studies in mice have shown that the class of flavanols found in cocoa boosts the performance of the dentate gyrus.
“The dentate gyrus in humans and mice are very similar,” says Small. “I suppose that our study does show, for the first time, that flavanols improve the function of humans’ dentate gyrus, particularly in ageing humans.”
The findings apply to normal age-related memory loss – things such as forgetting names of new acquaintances or where we left our glasses – which usually becomes noticeable when people reach their 50s or 60s. They do not apply to memory loss caused by disease, such as Alzheimer’s.
The cocoa drink was prepared by a large American food corporation, which partly supported the research. The firm used a proprietary process to extract the flavanols from cocoa beans, because under conventional processing, most of the flavanols are lost from the raw plant.
Small says it is too early to make dietary recommendations for flavanols.
“Certainly I would not suggest that people consume more chocolate. That would be a mistake,” he says. “Very simply, the amount of flavanols that are found in chocolate is minuscule compared to the very high amount of extracted flavanols that our subjects consumed. The same is true for most other foods or teas.
“Hopefully, in the future, a food source or a specific diet will be identified that contains very high amounts of the specific flavanols we studied.”
