Consuming foods rich in flavanols such as tea, chia seeds, apples and dark chocolate may stave off the risk of age-related memory loss, according to a large study.
The study, led by researchers at Columbia and Brigham and Women's Hospital/Harvard, showed that replenishing these bioactive dietary components in flavanol-deficient adults over age 60 showed an improvement in memory loss.
"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 Adam Brickman, Professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons.
The finding, Proceedings of the National Academy of Sciences, also supports the emerging idea that the ageing brain requires specific nutrients for optimal health, just as the developing brain requires specific nutrients for proper development.
"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," said Scott Small, Professor of Neurology at Columbia.
The study focussed on linking age-related memory loss to changes in the dentate gyrus, a specific area within the brain's hippocampus -- a region that is vital for learning new memories -- and showing that flavanols improved function in this brain region.
Their previous research, in mice, found that flavanols -- particularly a bioactive substance in flavanols called epicatechin -- improved memory by enhancing the growth of neurons and blood vessels and in the hippocampus.
In the new study, more than 3,500 healthy older adults were randomly assigned to receive a daily flavanol supplement (in pill form) or placebo pill for three years.
The active supplement contained 500 mg of flavanols, including 80 mg epicatechins, an amount that adults are advised to get from food.
Participants performed a series of web-based activities in their own homes, to assess the types of short-term memory governed by the hippocampus. The tests were repeated after years one, two, and three.
For those eating a healthy diet with plenty of flavanols, memory scores improved only slightly.
But 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 placebo and 16 per cent compared to their memory at baseline.
The results strongly suggest that flavanol deficiency is a driver of age-related memory loss, the researchers said.