Does Increased Polyphenol Intake Affect Cognitive Function?

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Cognitive aging, a term used to describe the normal decline in cognitive abilities during the aging process, is a common concern for many individuals. While various factors contribute to cognitive aging, including genetics and lifestyle, the role of dietary patterns and specific food constituents has gained significant attention. One such group of compounds are dietary flavanols, a subgroup of polyphenols, which are naturally found in select fruits and vegetables. Emerging research suggests that flavanols may have a positive impact on cognitive aging, particularly in relation to hippocampal-dependent memory. In this post, I will be focusing in on an update to a recent large-scale study that delves into the association between dietary flavanols, memory, and habitual diet quality in older adults.

“The study has investigated whether taking daily cocoa extract supplements containing 500 mg/day cocoa flavanols or a common multivitamin reduces the risk for developing heart disease, stroke, cancer, and other important health outcomes.”

The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is a clinical trial that randomized 21,442 men and women across the United States. The study has investigated whether taking daily cocoa extract supplements containing 500 mg/day cocoa flavanols or a common multivitamin reduces the risk for developing heart disease, stroke, cancer, and other important health outcomes. The clinical trial, known as the COcoa Supplement and Multivitamin Outcomes Study (COSMOS-Web), involved 3,562 older adults who were randomly assigned to either a daily intervention of cocoa extract containing 500 mg of cocoa flavanols or a placebo. The study update to COSMOS had participants followed over a 3-year period, and their memory performance and dietary habits assessed. Additionally, a subset of participants (n = 1,361) provided urine samples, allowing researchers to analyze biomarkers of flavanol intake. It is worth noting the impressive sample size and high-quality controlled study design.

The findings of the study revealed a positive correlation between habitual flavanol consumption, diet quality, and hippocampal-dependent memory. Participants with higher baseline flavanol intake and better diet quality demonstrated superior memory performance. However, the primary end point analysis of the longitudinal study after flavanol supplementation did not show a statistically significant improvement in memory among all participants after one year of intervention.

“Participants in the lower tertiles of diet quality or flavanol consumption experienced a statistically significant memory improvement following the flavanol intervention.”

However, the study found that the flavanol intervention did have a restorative effect on memory in individuals with lower habitual diet quality or lower flavanol consumption at baseline. Participants in the lower tertiles of diet quality or flavanol consumption experienced a statistically significant memory improvement following the flavanol intervention. Notably, enhanced memory performance was associated with an increase in the flavanol biomarker over the course of the trial suggesting causality.

These findings shed light on the potential role of dietary flavanols in the context of cognitive aging. While the overall improvement in memory among all participants was not statistically significant after one year, the study highlights the importance of habitual diet quality and flavanol consumption in modulating memory performance. The results suggest that individuals with lower diet quality or limited flavanol intake may benefit from flavanol interventions to mitigate the hippocampal-dependent component of cognitive aging.

“…following a largely plant-based diet with plenty of fruits and vegetables (flavanol-rich foods), we can potentially enhance cognitive aging and promote healthy brain function as we grow older.”

Cognitive aging is a significant concern for many individuals, and identifying modifiable factors such as dietary interventions can have a substantial impact on public health. The study discussed here provides valuable insights into the potential of dietary flavanols, found in specific fruits and vegetables, in influencing cognitive aging. While further research is needed to fully understand the mechanisms underlying the relationship between flavanols and memory, this study emphasizes the importance of a balanced diet rich in flavanol-containing foods for optimal cognitive health in older adults.

As we’ve mentioned many times in previous posts, following a largely plant-based diet, we can potentially enhance cognitive aging and promote healthy brain function as we grow older. Foods high in flavonoids include tea, fruit, vegetables, grains, legumes, nuts and wine. This is especially the case here in the US, where the average flavonoid consumption is only 190mg/day. This means that a large number of Americans would benefit from increasing their consumption of plant-based foods (in particular dark berries) or begin taking a flavanol supplement on a regular basis.

E. Dylan Mayer Dylan is a graduate from the University of Colorado at Boulder, with a major in Neuroscience and minor in Business. He has also recently completed his M.S. in Human Nutrition at Columbia University.

This article was reviewed and approved by Emeran Mayer, MD