Taking a daily flavanol supplement improves hippocampal-dependent memory in older adults who have a relatively poor diet, results of a large new study suggest.
There’s increasing evidence that certain nutrients are important for the aging body and brain, study investigator Scott Small, MD, the Boris and Rose Katz Professor of Neurology, Columbia University Vagelos College of Physicians and Surgeons, New York, told this news organization.
“With this new study, I think we can begin to say flavanols might be the first one that really is a nutrient for the aging brain.”
These findings, said Dr. Small, represent “the beginning of a new era” that will eventually lead to formal recommendations” related to ideal intake of flavanols to reduce cognitive aging.
The findings were published online in the Proceedings of the National Academy of Science.
Better cognitive aging
Cognitive aging refers to the decline in cognitive abilities that are not thought to be caused by neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Cognitive aging targets two areas of the brain: the hippocampus, which is related to memory function, and the prefrontal cortex, which is related to attention and executive function.
Previous research has linked flavanols, which are found in foods like apples, pears, berries, and cocoa beans, to improved cognitive aging. The evidence shows that consuming these nutrients might be associated with the hippocampal-dependent memory component of cognitive aging.
The new study, known as COcoa Supplement and Multivitamin Outcomes Study-Web (COSMOS-Web), included 3,562 generally healthy men and women, mean age 71 years, who were mostly well-educated and non-Hispanic/non-Latinx White individuals.
Participants were randomly assigned to receive oral flavanol-containing cocoa extract (500 mg of cocoa flavanols, including 80 mg of epicatechin) or a placebo daily.
The primary endpoint was hippocampal-dependent memory at year 1 as assessed with the ModRey, a neuropsychological test designed to measure hippocampal function.
Results showed participants in both groups had a typical learning (practice) effect, with similar improvements (d = 0.025; P = .42).
Researchers used other tests to measure cognition: the Color/Directional Flanker Task, a measure of prefrontal cortex function, and the ModBent, a measure that’s sensitive to dentate gyrus function. The flavanol intervention did not affect ModBent results or performance on the Flanker test after 1 year.
However, it was a different story for those with a poor diet at baseline. Researchers stratified participants into tertiles on the basis of diet quality as measured by the Healthy Eating Index (HEI) scores. Those in the lowest tertile had poorer baseline hippocampal-dependent memory performance but not memory related to the prefrontal cortex.
The flavanol intervention improved performance on the ModRey test, compared with placebo in participants in the low HEI tertile (overall effect: d = 0.086; P = .011) but not among those with a medium or high HEI at baseline.
“We confirmed that the flavanol intervention only benefits people who are relatively deficient at baseline,” said Dr. Small.
The correlation with hippocampal-dependent memory was confirmed in a subset of 1,361 study participants who provided a urine sample. Researchers measured urinary 5-(3′,4′-dihydroxyphenyl)-gamma-valerolactone metabolite (gVLM) concentrations, a validated biomarker of flavanol consumption.
After stratifying these results into tertiles, researchers found performance on the ModRey was significantly improved with the dietary flavanol intervention (overall effect: d = 0.141; P = .006) in the lowest gVLM tertile.