Study: Consuming More Antioxidant Flavonols May Slow Memory Decline

New research found that older adults who consume more flavonols — an antioxidant found in some fruits, vegetables, tea, and wine — may have a slower rate of memory decline.

Flavonols are a flavonoid subgroup known for their antioxidative and anti-inflammatory effects. Flavonoids also contribute to the pigments that give fruits and vegetables their vibrant color.

Previous research by scientists from the Rush University Medical Center in Chicago and Tufts University in Boston found that people with the highest intake of flavonols were 48% less likely to develop Alzheimer’s disease.

Moreover, earlier research by the group reported that kaempferol — a flavonol abundant in green leafy vegetables — was associated with a reduced rate of global cognitive decline.

Building on these findings, the research team sought to investigate the associations between total and specific flavonol intake and changes in cognitive performance.

The study, published November 22nd in Neurology — the medical journal of the American Academy of Neurology — suggests that people who consume more flavonol-rich foods and drinks may have a slower rate of memory decline.

To conduct the study, researchers recruited 961 people ages 60–100 years without dementia from the Rush Memory and Aging Project — a cohort of Chicago residents living in retirement communities and senior public housing.

The scientists followed the participants for almost seven years. Each year the participants completed questionnaires asking how often they ate 144 specific food items over the previous 12 months. They also underwent yearly cognitive assessments consisting of a battery of 19 standardized tests.

The scientists also collected information about the participant’s education, physical activity, and lifestyle choices.

According to the study, flavonol intake in the U.S. averages around 16–20 milligrams (mg) per day. However, among the study participants, flavonol intake was about 5 to 15 mg daily, with an average of about 10 mg per day.

After analyzing the data, the research team found that the participants with a higher intake of flavonols also had a slower rate of decline in multiple cognitive performance categories.

These categories include:

  • Global cognition
  • Semantic memory
  • Episodic memory
  • Perceptual speed
  • Working memory

These results remained consistent even after adjusting for factors such as sex, age, physical activity, and smoking status.

On average, participants with the highest levels of flavonol intake were younger and more educated. They also consumed fewer calories and were more physically and cognitively active than those with the lowest flavonol intakes.

The researchers also looked at the cognitive effects of specific flavonol components found in the food items participants frequently consumed.

These included:

Kaempferol: beans, kale, spinach, broccoli, and tea.

Quercetin: apples, tomatoes, kale, and tea.

Isorhamnetin: pears, tomato sauce, olive oil, and wine.

Myricetin: tea, wine, kale, oranges, and tomatoes.

After reviewing the data, the scientists found the following:

Higher kaempferol intake was associated with a slower decline in the global cognitive score, and all five cognitive domains

Higher quercetin intake was associated with a slower decline in episodic memory, global cognition, and semantic memory. It also may benefit perceptual speed and working memory.

Isorhamnetin and Myricetin were not associated with changes in cognitive abilities.

According to a press release, study author Thomas M. Holland, M.D., M.S. of Rush University Medical Center in Chicago, said, “it’s exciting that our study shows making specific diet choices may lead to a slower rate of cognitive decline.”

“Something as simple as eating more fruits and vegetables and drinking more tea is an easy way for people to take an active role in maintaining their brain health,” he added.

Holland also noted that although this study shows an association between higher flavonol intake and slower memory decline, the results do not prove flavonols are a direct cause of a slower rate of cognitive decline.

Additional limitations to the study include the participants were largely non-Latino white, highly educated, and reside in one region in the U.S. Therefore, it’s unknown if the results would be similar for other groups.

Also, food frequency was self-reported and dependent on participants remembering what they ate. The study authors note that this could result in over or underestimation of associations found in the study.

The National Institutes of Health, the National Institute on Aging, and the USDA Agricultural Research Service supported this research.

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