Flavanol-rich foods could help stave off age-related memory loss
A flavanol-rich diet could be the key to helping tackle age-related memory loss.
A large-scale study has shown that participants who had a poor diet at the start of a three-year trial and who consumed 500mg of flavanol a day in supplement form, showed improved memory function.
The research, published in the journal Proceedings of the National Academy of Sciences (Pnas) and led by teams from Columbia and Brigham and Women’s Hospital/Harvard in the US, is the first to establish that a diet low in flavanols – nutrients found in certain fruits and vegetables such as berries, apples, green tea, and cocoa – drives age-related cognitive decline.
Co-leader of the study, Adam Brickman, professor of neuropsychology at Columbia University’s Vagelos College of Physicians and Surgeons in New York, said the findings “raises the possibility of using flavanol-rich diets or supplements to improve cognitive function in older adults.”
The findings also support the emerging idea that the ageing brain needs specific nutrients for optimal health, just as a developing one requires certain vitamins, proteins and minerals for proper development.
The study’s senior author, Scott Small, the Boris and Rose Katz professor of neurology at Columbia University, said: “The identification of nutrients critical for the proper development of an infant’s nervous system was a crowning achievement of 20th Century nutrition science.
“In this century, as we are living longer research is starting to reveal that different nutrients are needed to fortify our ageing minds. Our study, which relies on biomarkers of flavanol consumption, can be used as a template by other researchers to identify additional, necessary nutrients.” 
For the current study 3,500 healthy adults were randomly assigned to receive a 500mg flavanol supplement or a placebo pill. The active supplement contained 500mg of flavanols, including 80mg epicatechins, an amount that adults are advised to get from food.
The participants took several memory tests during the three year study period and filled out surveys that assessed their diet, including foods known to be high in flavanols.
More than a third of the participants also supplied urine samples that allowed researchers to measure a biomarker for dietary flavanol levels, developed by co-study authors at Reading University in the UK, before and during the study.
The biomarker gave the researchers a more precise way to determine if flavanol levels corresponded to performance on the cognitive tests and ensure that participants were sticking to their assigned regimen.
Flavanol levels varied moderately, though no participants were severely flavanol-deficient.
The researchers said memory scores improved only slightly for the entire group taking the daily flavanol supplement, most of whom were already eating a healthy diet.
But within that group the researchers found that participants who had a poor diet and low flavanol consumption at the beginning of the study, showed bigger improvements in their memory.
This group saw memory scores increase by an average of 10.5% compared to placebo and 16% in contrast to their memory at baseline.
Annual cognitive testing showed the improvement observed at one year was sustained for at least two more years.
The results strongly suggest that flavanol deficiency is a driver of age-related memory loss, the researchers said. This was because flavanol consumption correlated with memory scores and flavanol supplements improved memory in flavanol-deficient adults.
The findings of the new study are consistent with those of recent research which found that flavanol supplements did not improve memory in a group of people with a range of baseline flavanol levels.
The previous study did not look at the effects of flavanol supplements on people with low and high flavanol levels separately, however.
Dr Small said: “What both studies show is that flavanols have no effect on people who don’t have a flavanol deficiency.”
He added: “We cannot yet definitively conclude that low dietary intake of flavanols alone causes poor memory performance, because we did not conduct the opposite experiment: depleting flavanol in people who are not deficient,” adding that such an experiment might be considered unethical.
The next step needed to confirm flavanols’ effect on the brain, Dr Small said, is a clinical trial to restore their levels in adults with severe deficiency of the naturally occurring compound.
“Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability,” Dr Small explained. “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.”
Commenting on the study, Dr Ian Johnson, Emeritus Fellow at the Quadram Institute in Norwich in the UK, said: “This large and rigorously conducted study adds strong support to previous evidence showing the importance of diet as a factor supporting cognitive health in later life. It demonstrates that older adults consuming lower levels of food-borne flavanols scored less well in tests of hippocampal memory function than individuals consuming higher levels.”
He added: “These results emphasise the role of nutrition in the maintenance of the ageing brain, and in particular they suggest the importance of maintaining a high-quality diet, rich in everyday sources of flavanols such as apples, grapes, other berries, and tea.
“In circumstances where this is difficult, the use of dietary supplements may be a practical solution, though further studies are probably needed to explore this approach in depth.”
Professor Aedin Cassidy, chair in Nutrition and Preventative Medicine and director for Interdisciplinary Research, Institute for Global Food Security, at Queen’s University Belfast (QUB), said: “This is a really important study showing that dose of flavonoids called flavanols, present in tea, cocoa, apples, and berries is key for improving memory in the ageing brain.
“Although we have animal experiments and short term human studies showing that flavanols improve cognitive function, this is the first long term three year intervention trial showing that dietary flavanols can restore memory in older adults whose general diet was of poor quality.”
He concluded: “The dose required for these improvements in brain health are readily achievable – for example one mug of tea, six squares of dark chocolate, a couple of servings of berries/apples would together provide about 500mg of flavanols.”
But not everyone agrees with the findings of the study.
Professor David Curtis, Honorary Professor at the UCL Genetics Institute in London, said: “I’m afraid that the results obtained do not support the claim that flavanols improve memory function. Even in the group who initially had low flavanol consumption, those taking a flavanol supplement for years had about the same memory function as those taking placebo and any differences were well within chance expectation.
“The authors do claim that a couple of results are statistically significant but in my view this is because the analyses have been performed incorrectly. If anything, this study shows that flavanol supplements do not have any major effect on memory function.
“The study fails to provide evidence that increasing flavanol intake is beneficial and there is no need for anybody to contemplate changing their diet in the light of its findings.”
