Memory loss can be reversed by increasing intake of foods such as green tea, apples and berries, new research suggests.
The study is the first to show that a diet with insufficient flavanols – nutrients found in certain fruits and vegetables – stops the brain functioning at its best, and drives memory loss.
Flavonols are present in many foods including green leafy vegetables, blackcurrants, onions, apples, berries, cherries, peaches, soybeans, citrus foods, tea, chocolate, lettuce, peppers, grapes and even wine.
The study by US researchers found that over-60s who already consumed sufficient flavanols saw no benefit when they added more, but those with deficits recorded memory improvements of an average of 16 per cent in a year.
“The improvement among study participants with low-flavanol diets was substantial and raises the possibility of using flavanol-rich diets or supplements to improve cognitive function in older adults,” said Dr Adam Brickman, professor of neuropsychology at Columbia University.
Experts said the finding supports the idea that the ageing brain requires specific nutrients to stay functioning well, just as the developing brain of children requires specific nutrients for proper growth.
Previous studies in animals have shown that flavanols boost the growth of neurons and blood vessels in the hippocampus – a region of the brain which is crucial for learning and developing new memories.
For the study, more than 3,500 healthy older adults were randomly assigned to receive a daily flavanol supplement pill or placebo pill for three years.
The active supplement contained 500 mg of flavanols, a daily amount that adults are advised to get from food.
Such a dose could be achieved naturally through one mug of tea, six squares of dark chocolate , and a couple of servings of berries or apples. ‘Really important’ research
At the beginning of the study, all participants completed a survey that assessed the quality of their diet, and performed a series of web-based activities in their own homes, designed to test their short-term memory.
The tests were then repeated after years one, two, and three.
At the end of the first year of taking the flavanol supplement, participants who reported consuming a poorer diet and had lower baseline levels of flavanols saw their memory scores increase by an average of 10.5 per cent, compared to those who took the placebo pill, and 16 per cent compared to their memory at baseline.
And the improvement lasted for at least two more years.
Commenting on the research, Prof Aedin Cassidy, Chair in Nutrition & Preventative Medicine at Queen’s University Belfast (QUB), said: “This is a really important study showing that [a] dose of flavonoids called flavanols, present in tea, cocoa, apples, and berries, is key for improving memory in the ageing brain.
“Supplementing with flavanols reversed the lower memory in the participants who had low diet quality after one year of intake and this was sustained throughout the three year intervention period.
“So when habitual diets are not as healthy as they could be, we now have evidence that simple additions to the diet like flavanols can contribute to maintaining brain health as we age.”
The team said they could not definitively conclude that low dietary intake of flavanols alone causes poor memory performance, because they did not conduct an experiment where they removed flavanol to see if it made memory worse.
To find out for sure, they now want to conduct a clinical trial in which they restore flavanol levels in adults with severe flavanol deficiency to see if it improves memory.
“Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability,” said Dr Scott Small, Professor of Neurology at Columbia University.
“If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they’re in their 40s and 50s.”
The research was published in the journal PNAS.
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