Antioxidant flavonols may prevent memory loss: Study

According to a study published in the online edition of Neurology, the medical journal of the American Academy of Neurology, on November 22, 2022, people who consume more foods high in the antioxidant flavonols, which are present in many fruits and vegetables as well as tea and wine, may experience a slower rate of memory deterioration.

“It’s exciting that our study shows making specific diet choices may lead to a slower rate of cognitive decline,” said study author Thomas M. Holland, MD, MS of Rush University Medical Center in Chicago. “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.”

Flavonoids, a class of phytochemicals present in plant pigments and recognised for their positive health benefits, including flavonols. The average age of the 961 participants in the trial without dementia was 81. Each year, they responded to a questionnaire on their dietary habits.

Additionally, they had yearly cognitive and memory assessments that involved placing numbers in the right order, memorising lists of words, and recalling word lists. In addition, questions regarding their level of schooling, how much time they spent exercising, and how much time they spent doing cognitively stimulating things like reading and playing video games were asked. They had an average of seven years of follow-up.

Depending on how many flavonols they consumed, the population was split into five equal groups. The research group had an average dietary intake of total flavonols of around 10 mg per day, compared to the average amount of flavonols consumed by US adults, which ranges from 16 to 20 milligrammes (mg) per day.

The top group ingested an average of 15 mg per day, which is about comparable to one cup of dark leafy greens, whereas the lowest group consumed just approximately 5 mg daily.

Researchers utilised a total global cognition score that represented the results of 19 cognitive tests to calculate rates of cognitive decline. For those with no cognitive issues, the average score was 0.5; for those with moderate cognitive impairment, it was 0.2; and for those with Alzheimer’s disease, it was -0.5.

Researchers discovered that the cognitive score of those with the highest intake of flavonols fell at a pace of 0.4 units per decade less slowly than those with the lowest intake after controlling for other variables that may impact the rate of memory decline, such as age, sex, and smoking. Holland remarked that this is likely caused by flavonols’ innate anti-inflammatory and antioxidant capabilities.

The four components of the flavonol class—kaempferol, quercetin, myricetin, and isorhamnetin—were also broken down in the study. For example, kale, beans, tea, spinach, and broccoli contributed the most kaempferol; tomatoes, kale, apples, and tea contributed the most quercetin; tea, wine, kale, oranges, and tomatoes contributed the most myricetin; and pears, olive oil, wine, and tomato sauce contributed the most isorhamnetin.

The rate of cognitive deterioration was 0.4 units per decade slower in individuals with the highest consumption of kaempferol than in those with the lowest intake. The rate of cognitive deterioration was 0.2 units per decade slower among individuals who consumed the most quercetin compared to those who consumed the least. Additionally, individuals who consumed the most myricetin had a rate of cognitive deterioration that was 0.3 units per decade lower than those who consumed the least. Global cognition and dietary isorhamnetin were not related.

Holland pointed out that while the study does not establish that dietary flavonols directly contribute to a slower pace of cognitive decline, it does demonstrate a relationship between greater intakes of dietary flavonols and a slower rate of cognitive decline.