Antioxidants flavonols associated with slower memory loss
Abstract: Increased consumption of foods and beverages high in the antioxidant flavonol helps slow memory and cognitive decline, a new study reports.
People who eat or drink more foods with antioxidant flavonols, found in several fruits and vegetables as well as tea and wine, may have a slower rate of memory decline, according to a study published in the Nov. 22, 2022, online edition of the journal. Neurology.
“It is exciting that our study shows that certain 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 effects on health.
961 people with an average age of 81 without dementia participated in the research. 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 spent doing physical activities, and how much time they spent doing mentally engaging activities like reading and playing games. They were followed for an average of seven years.
People were divided into five equal groups based on the amount of flavonols they had in their diet. While the average amount of flavonol intake in US adults is about 16 to 20 milligrams (mg) per day, the study population had an average total dietary flavonol intake 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 one cup of dark leafy vegetables.
To determine rates of cognitive decline, the researchers used a total global cognitive ability score summarizing 19 cognitive tests. The average score ranged from 0.5 for people without thinking problems to 0.2 for people with mild cognitive impairment to -0.5 for people with Alzheimer’s disease.
After adjusting for other factors that could affect the rate of memory decline, such as age, gender and smoking, the researchers found that the cognitive score of people with the highest intake of flavonols declined at a rate of 0.4 units per decade slower than people whose intake was the smallest. Holland noted that this is likely due to the inherent antioxidant and anti-inflammatory properties of flavonols.
The study also divided the flavonol class into four compounds: kaempferol, quercetin, myricetin, and isorhamnetin.
The foods that contributed the most to 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 with the highest intake of kaempferol had a 0.4 unit per decade slower rate of cognitive decline compared to those in the lowest group. Those with the highest quercetin intake had a 0.2 unit per decade slower rate of cognitive decline compared to those in the lowest group. And people with the highest myricetin intake had a 0.3 unit per decade slower rate of cognitive decline compared to those in the lowest group. Dietary isorhamnetin was not related to global cognition.
Holland noted that the study shows an association between higher amounts of flavonols in the diet 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 remember exactly what they ate.
Financing: The study was supported by the National Institutes of Health, the National Institute on Aging and the USDA Agricultural Research Service.
About this diet and memory research news
Original research: Findings will appear in Neurology