Wine and Tea Polyphenols Can Reduce Cognitive Decline

Study finds that eating leafy greens or drinking tea and wine, which all contain flavonols, improves overall brain health and may protect against Alzheimer's and dementia

Wine and Tea Polyphenols Can Reduce Cognitive Decline
What do leafy greens and red wines have in common? Flavonols, a class of polyphenols that protects plants from too much sun. (Luis Alvarez/Getty)
Dec 21, 2022

New research adds to abundant evidence that antioxidants found in wine, tea and many fruits and vegetables can powerfully shape brain health as people age. In a study published in November in Neurology, the medical journal of the American Academy of Neurology, scientists at Chicago's Rush University Medical Center found that higher intake of flavonols, a class of bioactive polyphenolic compounds found in significant concentrations in tea and wine, slows overall cognitive decline and improves long-term brain health. The study follows similar research by the same team in 2020 that specifically linked flavonols with reduced risk of Alzheimer's.

Analyzing data from the Rush Memory and Aging Project (MAP), an ongoing community-based cohort study of older adults in Chicago that began in 2004, the researchers tracked flavonol intake and overall cognitive decline for 961 participants. Specifically, they compared levels of consumption of four major flavonols—kaempferol, quercetin, myricetin and isorhamnetin—with several indicators of brain health, including episodic memory, semantic memory, visuospatial ability, perceptual speed and working memory. These brain health indicators were measured annually using a battery of 19 cognitive tests.

The researchers found that higher total flavonol intake, especially of quercetin and kaempferol, was strongly linked with improved neurological performance. Compared to those who consumed the lowest amount of flavonols, people in the highest quintile of flavonol consumption (equivalent to seven servings of dark leafy greens per week) showed a 32 percent decrease in cognitive decline.

While many wine drinkers know about resveratrol, which belongs to a class of polyphenols called stilbenoids, flavonols may be less familiar. (Confusingly, they are related to flavanols, yet another class of bioactive compounds found in wine. No one said organic chemistry was easy.) All of these compounds are antioxidants that possess anti-inflammatory properties, which can have significant health effects, especially as people age. The new study is one of the first to demonstrate links between flavonols specifically and brain health in humans.

Dr. Thomas Holland, lead author of the study and a physician scientist at the Rush Institute for Health Aging, told Wine Spectator that a balanced diet is key to long-term brain health. He advises people to "eat your fruits and vegetables, particularly dark leafy greens, and drink some tea and/or wine every now and again."

Holland adds that "nuts, berries, beans, whole grains, fish, poultry and extra virgin olive oil" are also good to include in a balanced diet, which allows "for an optimized intake of a diverse quantity and quality of vitamins, minerals and bioactives."

Flavonols—which according to Holland are primarily found in kale, beans, tea, spinach, broccoli, tomatoes, apples, wine, oranges, pears and olive oil—are made by plants in response to sun exposure. They're found in high concentrations in grape skins, which explains why young red wines, especially those with higher tannins, may offer the greatest health benefits. Similarly, green tea contains more flavonols than black tea.

The study participants ranged from 58 to 100 years old and were primarily female, white and highly educated. The study also notes that "participants with the highest levels of flavonol intake were on average younger, more educated, consumed fewer calories and were more physically and cognitively active than those with the lowest flavonol intakes." Though the study controlled for potentially confounding lifestyle factors, it relied on self-reported dietary intake, which is prone to recall bias.

Holland emphasizes that it's relatively easy to consume a high level of neuroprotective flavonols. To achieve the highest quintile of flavonol consumption highlighted in the study, a person would have to eat just a single serving of dark leafy greens a day or drink 3–4 cups of green tea. While he reiterates the importance of a balanced diet of fruits and vegetables, Holland says tea and wine "can certainly be a part of a healthy diet."

He also points out that flavonols are just one piece of the dietary puzzle, which itself is just one aspect of long-term brain health. "Lifestyle modifications that have been shown to have an association to either delayed cognitive decline or a reduced risk of Alzheimer's dementia include, but are not limited to, moderate to vigorous physical activity, an active social life, cognitively stimulating activities like visiting museums, reading books, or starting a new hobby, good quality and quantity of sleep, and stress reduction."


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