Diets low in flavonols may drive age-related memory loss, according to a large-scale study by researchers at Columbia and at Harvard's Brigham and Women's Hospital
The study found that flavonol intake among older adults coincides with test scores that detect memory loss due to normal aging. Replenishing these bioactive dietary components in mildly flavonol-deficient adults older than 60 improved performance. The finding also supports the emerging idea that the aging brain requires specific nutrients for optimal health, just as the developing brain requires specific nutrients for proper development.
Per the study, more than 3,500 healthy older adults were randomly assigned to receive a daily flavonol supplement or placebo pill for three years. The active supplement contained 500 mg of flavonols, including 80 mg of epicatechins, an amount that adults are advised to get from food.
At the beginning of the study, all participants completed a survey that assessed the quality of their diet, including foods known to be high in flavonols. Participants then 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 annually.
More than a third of the participants also supplied urine samples that allowed researchers to measure a biomarker for dietary flavonol levels. The biomarker gave the researchers a more precise way to determine if flavonol levels corresponded to performance on the cognitive tests and ensure that participants were sticking to their assigned regimen. Flavonol levels varied moderately, though no participants were severely flavonol-deficient.
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Memory scores improved only slightly for the entire group taking the daily flavonol supplement, most of whom were already eating a healthy diet with plenty of flavonols. But at the end of the first year of taking the flavonol supplement, participants who reported consuming a poorer diet and had lower baseline levels of flavonols saw their memory scores increase by an average of 10.5% compared to placebo and 16% compared to their memory at baseline. Annual cognitive testing showed the improvement observed at one year was sustained for at least two more years.
According to the study's senior author, Scott Small, M.D., the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeon, the results strongly suggest that flavonol deficiency is a driver of age-related memory loss. The next step needed is to confirm flavonols' effect on the brain via a clinical trial to restore flavonol levels in adults with severe flavonol deficiency.
"Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability," Small said. "If some of this variance is partly due to differences in dietary consumption of flavonols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavonols when they're in their 40s and 50s."
"The improvement among study participants with low-flavonol diets was substantial and raises the possibility of using flavonol-rich diets or supplements to improve cognitive function in older adults," said Adam Brickman, Ph.D., professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons and co-leader of the study.
