Flavanols are compounds found in many plant-based foods that have documented health benefits.
Many of these benefits stem from antioxidative effects, as well as improvements to peripheral endothelial function.
Emerging research indicates that these improvements may also benefit cognitive function, providing all the more reason to enjoy some dark chocolate.
It’s not often that the most delicious foods happen to be the most nutritious. But for the fortunate chocoholics among you, flavanol-rich dark chocolate falls into this category.
Research has established that the flavanols in dark chocolate (along with other foods) can help manage blood pressure, reduce cardiovascular risk, and reduce the risk of type 2 diabetes. Now, new evidence is emerging that points to possible cognitive benefits as well.
What are flavanols?
First, it helps to understand what flavanols are and how they affect specific systems in the body.
Flavanols are polyphenols that occur naturally in certain fruits and vegetables. Their positive effects on diseases such as diabetes and metabolic syndrome have been linked to how they interact with different pathways and help regulate certain immunologic reactions involving inducible enzymes, adhesion molecules, chemokines, and pro-inflammatory cytokines. Flavanols may even affect gut microbiome composition and function.
These compounds play a critical role in plants. Flavonoids (a type of flavanol) help plants cope with harsh environments and control cell growth and differentiation. Many of these functions are linked to the antioxidative properties of flavanols.
What foods contain flavanols?
Individuals who wish to add flavanols to their diet can choose from many delicious foods that range in taste from sweet, to tart, to savory.
Flavanols and flavonoids are found in most plants as well as plant-based foods.
Some common sources include tea, fruit, vegetables, grains, legumes, nuts, and wine.
Some of the most abundant food sources of flavanols include:
Green and black tea
In the Western diet, tea and wine tend to be the most common sources. But before you or your patients start reaching for the nearest corkscrew, remember what the World Health Organization has determined:
“When it comes to alcohol consumption, there is no safe amount that does not affect health.”
The 2020-2025 Dietary Guidelines for Americans recommend abstinence from alcohol or sticking to two or fewer drinks a day for men and no more than one drink for women. In addition, the guidelines do not recommend that individuals who don’t already drink alcohol start drinking for any reason.
How flavanols affect cognitive function
Of course, excess wine won’t improve cognition either. But other flavanol-rich foods may, and a study published in Scientific Reports helps elucidate why.
The double-blind study included 18 healthy male participants ranging from ages 18 to 45.
The intervention arm received a high-flavanol cocoa drink, and the control arm received a low-flavanol cocoa drink. The drinks were administered once weekly for 2 weeks.
At each visit, researchers took baseline measures, in this order: diastolic and systolic blood pressure, brachial artery flow-mediated dilation (FMD), and fNIRS of frontal cortex oxygenation/deoxygenation at rest and during hypercapnia. Participants then consumed their drinks within 10 minutes.
After 2 hours, the researchers reassessed blood pressure, FMD, and fNIRS-based reactivity to hypercapnic challenge. At this time, cognitive function was assessed using a Modified Stroop Task.
The results demonstrated that flavanols led to more rapid and enhanced brain oxygenation responses to hypercapnia.
They also improved cognitive performance in situations where cognitive demand was high.
These findings, the researchers observed, dovetail with previous research demonstrating that cocoa flavanols improve peripheral endothelial function, presumably through nitric oxide signaling.
“We suggest that the underlying mechanisms at play centrally may be similar to the ones detected in the peripheral vasculature, through hypercapnia-induced increases in NO release from the endothelium in cerebral arteries,” the researchers wrote.
In this study, the participants were all healthy, but the researchers noted that their results may have future implications for at-risk populations, such as people who smoke, have hypertension or diabetes, or are elderly.
“Another emerging line of research further suggests that this class of plant-derived compounds may protect against cognitive decline in aging and cognitive resilience to neuropsychiatric disorders and stress,” the researchers wrote, but they indicated that the mechanisms for any such benefits are not known at this time.
Cognitive decline in aging is becoming a pressing issue as the population ages. The looming problem has been called an “impending cognitive epidemic” by researchers who have studied cognitive aging.
These researchers conducted a study investigating the effects of flavanols on cognitive tasks in older adults. This controlled, randomized, parallel-arm study involved 211 healthy adults between the ages of 50 and 75. The participants received 260, 510, and 770 mgs of cocoa flavanols daily for 12 weeks, followed by an 8-week break.
Researchers assessed the effects by having the participants perform three tasks: a newly developed object-recognition task (which involves the hippocampus’ dentate gyrus), a hippocampal-dependent list-learning task, and a prefrontal cortex–dependent list-sorting task.
Results indicated that the object recognition assessment and the list-sorting assessment did not correlate with baseline diet or supplemental flavanols. But performance on the hippocampal-dependent list-learning task was associated with baseline diet quality and flavanols, particularly among participants who were dietarily deficient.
"While replication is needed, these findings suggest that diet in general, and dietary flavanols in particular, may be associated with memory function of the aging hippocampus and normal cognitive decline.” — Sloan RP, et al. Scientific Reports"
— Sloan RP, et al. Scientific Reports
This research may open the door for flavanol supplementation among at-risk populations, which may include the elderly or people whose diets are deficient in the compounds. And that’s good (if not delicious) news for a graying global population.
What this means for you
Research on the potential cognitive benefits of flavanols is still in its infancy. But so far, there appears to be a connection between the peripheral endothelial improvements and cognitive benefits. These findings, coupled with already established cardiovascular benefits, may provide all the evidence you or your patients need to enjoy some flavanol-rich foods, like tea or dark chocolate.