The dietary consumption of flavanols, which are found in a number of fruits and vegetables, can improve hippocampal-dependent memory in older adults with relatively poor habitual diets, according to study findings published in the Proceedings of the National Academy of Science.
Prior analyses have shown that the consumption of flavanols might lead to improvement in the hippocampal-dependent memory component of cognitive aging.
For the study, COcoa Supplement and Multivitamin Outcomes Study-Web (COSMOS-Web; ClinicalTrials.gov Identifier: NCT04582617), researchers included a total of 3,562 participants (mean age, 71) who were non-Hispanic/non-Latinx White individuals; most had college or postcollegiate degrees. The researchers randomly assigned participants to receive cocoa extract (ie, 500 mg of cocoa flavanols per day; n=1,744) or placebo (n=1,818).
The primary study outcome was the ModRey, which was used as the cognitive measure of hippocampal memory. Secondary outcomes included the Color/Directional Flanker Task, which is a cognitive measure of prefrontal cortex function, and the ModBent, which was recently designed as a measure with sensitivity to the function of dentate gyrus.
The researchers found that participants in both groups showed a typical learning (practice) effect with similar improvements (d= .025; P =.42). After 1-year, they also found that the flavanol intervention did not have an effect on ModBent results or performance on the Flanker test.
The researchers stratified participants into tertiles based on their diet quality measured by the alternative Healthy Eating Index (aHEI). For participants who had a poor diet at baseline, those in the lowest tertile had poorer hippocampal-dependent memory performance, but not memory related to the prefrontal cortex.
Compared with placebo, the flavanol intervention improved performance on the ModRey test in participants in the low aHEI tertile (overall effect: d =.086; P =.011)
Additionally, a urine-based biomarker of flavanol intake — 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone metabolite (gVLM) — was evaluated in a subset of 1,361 individuals. Via use of these measures, the researchers revealed that there was a correlation with hippocampal-dependent memory.
When the researchers stratified these results into tertiles, they found that performance on the ModRey significantly improved with the dietary flavanol intervention (overall effect: d =.141, P =.006) in the lowest gVLM tertile.
For these participants, when they consumed the dietary flavanol, their flavanol levels went back to normal and their memory was restored, the researchers noted.
The researchers did acknowledge that the mechanism behind flavanols and improved memory is not clear.
Study limitations included a lack of generalizability as the results only applied to older adults and a weaker effect size.
“Our findings suggest that flavanol consumption might be considered in future dietary recommendations, perhaps together with the flavanol biomarker, specifically geared toward preventing or improving brain health in later life,” the researchers concluded.
Disclosure: Some of the study authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Brickman AM, Yeung L-K, Alschuler DM, et al. Dietary flavanols restore hippocampal-dependent memory in older adults with lower diet quality and lower habitual flavanol consumption. PNAS. 2023;120(23):e2216932120. doi:10.1073/pnas.2216932120