Antioxidant flavonols – from fruit, tea and wine – linked to slower memory loss

Red wine bottle glass grapes

A new study has found that people who eat or drink more foods with antioxidant flavonols may experience slower memory decline as they age.

People who eat or drink more foods with antioxidant flavonols, found in tea and wine as well as several fruits and vegetables, may have a slower rate of memory decline, according to new research. The study was published in the November 22, 2022 online edition Neurologymedical journal of the American Academy of Neurology.

“It’s exciting that our study shows that specific dietary choices can lead to slower cognitive decline,” said study author Thomas M. Holland, MD, MS of Rush University Medical Center in Chicago. “Something as simple as eating more fruit and vegetables and drinking more tea is an easy way for people to take an active role in keeping their brains healthy.”

Flavonols are a type of flavonoids, a group of phytochemicals found in plant pigments known for their beneficial health effects.

Study participants included 961 people without dementia with an average age of 81 years. Every year they filled out a questionnaire about how often they eat certain foods. They also completed annual cognitive and memory tests including recalling lists of words, remembering numbers and putting them in the correct order. They were also asked about other factors such as their level of education, how much time they spend on physical activities, and how much time they spend on mentally engaging activities such as reading and playing games. They were followed for an average of seven years.

The researchers divided the people into five equal groups based on the amount of flavonols they had in their diet. While the average amount of flavonol intake for US adults is about 16 to 20 milligrams (mg) per day, the study population had an average dietary intake of total flavonols of approximately 10 mg per day. The lowest group had an intake of about 5 mg per day, and the highest group consumed an average of 15 mg per day; which is equivalent to about one cup of dark leafy greens.

“Something as simple as eating more fruit and vegetables and drinking more tea is an easy way for people to take an active role in keeping their brains healthy.” — Thomas M. Holland, MD, MS

To determine the rate of cognitive decline, the researchers used a total global cognitive ability score summarizing 19 cognitive tests. Mean scores ranged from 0.5 for people without thinking problems to 0.2 for people with mild cognitive impairment to -0.5 for people with[{” attribute=””>Alzheimer’s disease.

After adjusting for other factors that could affect the rate of memory decline, such as age, sex and smoking, researchers found that the cognitive score of people who had the highest intake of flavonols declined at a rate of 0.4 units per decade more slowly than people whose had the lowest intake. Holland noted this is probably due to the inherent antioxidant and anti-inflammatory properties of flavonols.

The study also broke the flavonol class down into the four constituents: kaempferol, quercetin, myricetin and isorhamnetin. The top food contributors for each category were: kale, beans, tea, spinach and broccoli for kaempferol; tomatoes, kale, apples and tea for quercetin; tea, wine, kale, oranges and tomatoes for myricetin; and pears, olive oil, wine and tomato sauce for isorhamnetin.

People who had the highest intake of kaempferol had a 0.4 units per decade slower rate of cognitive decline compared to those in the lowest group. Those with the highest intake of quercetin had a 0.2 units per decade slower rate of cognitive decline compared to those in the lowest group. And people with the highest intake of myricetin had a 0.3 units per decade slower rate of cognitive decline compared to those in the lowest group. Dietary isorhamnetin was not tied to global cognition.

Holland noted that the study shows an association between higher amounts of dietary flavonols and slower cognitive decline but does not prove that flavonols directly cause a slower rate of cognitive decline.

Other limitations of the study are that the food frequency questionnaire, although valid, was self-reported, so people may not accurately remember what they eat.

Reference: “Association of Dietary Intake of Flavonols With Changes in Global Cognition and Several Cognitive Abilities” by Thomas Monroe Holland, Puja Agarwal, Yamin Wang, Klodian Dhana, Sue E. Leurgans, Kyla Shea, Sarah L Booth, Kumar Rajan, Julie A. Schneider and Lisa L. Barnes, 22 November 2022, Neurology.
DOI: 10.1212/WNL.0000000000201541

The study was supported by the National Institutes of Health, National Institute on Aging, and USDA Agricultural Research Service.

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