Consuming foods and drinks that contain flavonols may help preserve memory and cognitive abilities over time.
In particular, three specific components of flavonols: kaempferol, myricetin and quercetin, have been associated with slower overall cognitive decline.
New research published in Neurology, the official journal of the American Academy of Neurology, suggests that dietary intake of flavonols may slow the rate of decline in global cognition and multiple cognitive abilities associated with ageing.
Improvements were found in episodic memory, semantic memory, visuospatial ability, perceptual speed and working memory.
The foods that contributed the most to each antioxidant 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.
The researchers used data from the Rush Memory and Aging Project (MAP), a cohort of Chicago residents from retirement communities and public housing for the elderly without known dementia at baseline.
The trial involved about 960 participants with an average age of 81 years, who were followed for an average of 7 years.
The majority (75%) were female and white (98%).
Each year, the participants completed a questionnaire about how often they ate certain foods and underwent cognitive and memory tests, including recalling lists of words, memorising numbers and putting them in the right order.
Participants also reported their level of education, time spent on physical activities and mental activities such as reading and playing games.
The participants were divided into five groups according to the amount of flavonols they consumed.
The average amount of flavonols consumed by US adults is about 16-20 mg per day, while in the study the group with the lowest flavonol intake was about 5 mg per day and the group with the highest was 15 mg per day, the equivalent of 1 cup of dark leafy vegetables.
To determine the rate of cognitive decline, the researchers used a global cognition score that combined 19 cognitive tests.
The average score ranged from 0.5 for those with no cognitive impairment to 0.2 for those with mild cognitive impairment and -0.5 for those with Alzheimer’s disease.
After adjusting for factors that could have influenced the rate of memory decline, such as age, gender and smoking, the researchers found that the cognitive score of those with the highest flavonol intake (equivalent to one serving of leafy greens per day) had a 32 percent reduction in the rate of cognitive decline compared to those with the lowest intake.
The study’s first author, Dr. Thomas Holland, is an assistant professor at the Rush Institute for Aging at Rush University Medical Center in Chicago, Ill.
Holland, noted that as we age, free radicals can lead to cell damage known as oxidative stress.
“When we consume foods that contain antioxidants, such as flavonols or vitamin E, these antioxidants act as reducing agents, essentially destroying free radicals and preventing further cell damage,” Thomas Holland said.
When the researchers divided flavonols into four components – kaempferol, quercetin, myricetin and isoramnetin – they found that participants with the highest intake of kaempferol, found in foods such as kale, beans, tea, spinach and broccoli, had a 32 per cent slower rate of cognitive decline than those with the lowest kaempferol intake.
People with the highest intake of quercetin, found in tomatoes, kale, apples and tea, had a 30 per cent slower rate of cognitive decline than those who consumed less quercetin.
Participants with the highest intake of myricetin, found in wine, kale, oranges and tomatoes, experienced a 31 per cent slower rate of cognitive decline than those with the lowest intake.
Dietary isoramnetin was not associated with global cognition.
Limitations of the study include the potential risk of bias due to self-reported dietary intake and the fact that the MAP participants may have been at risk of cognitive impairment or subclinical disease due to their age, making reports of dietary intake less reliable.
The Cocoa, Cognition, and Aging (CoCoA) Study (2014-12-04)
Bioactive compounds in berries can reduce high blood pressure (16/01/2010)
Flavonoid-rich foods and drinks may prevent erectile dysfunction (2016-01-26)
Substance in tangerines fights obesity and protects against heart disease (07/04/2011)
For more information
Association of Dietary Intake of Flavonols With Changes in Global Cognition and Several Cognitive Abilities
Thomas Monroe Holland, Puja Agarwal, Yamin Wang, Klodian Dhana, Sue E. Leurgans, Kyla Shea, Sarah L Booth, Kumar Rajan, Julie A. Schneider, Lisa L. Barnes
A higher habitual flavonoid intake is associated with a lower risk of atrial fibrillation
Flavonoid intake and its association with atrial fibrillation
Marco Dal Negro
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