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 online issue of the. November 22, 2022 of Neurology, the medical journal of the American Academy of Neurology.
“It’s exciting that our study shows that making specific food choices can lead to a slowing 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 to take an active role in maintaining brain health.”
Flavonols are a type of flavonoid, a group of phytochemicals found in plant pigments that are known for their health benefits.
The study involved 961 people with an average age of 81 without dementia. Each year they filled out a questionnaire on how often they ate certain foods. They also completed yearly cognitive and memory tests, including recalling lists of words, memorizing numbers, and placing them in the correct order. They were also asked about other factors, such as education level, time devoted to physical activities, and time devoted to mentally engaging activities, such as reading and games. They were followed up for an average of seven years.
People were divided into five equal groups based on the amount of flavonols in their diets. While the average amount of flavonols ingested by US adults is approximately 16 to 20 milligrams (mg) per day, the study population had an average intake of total dietary 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 equals about a cup of dark leafy greens.
To determine rates of cognitive decline, the researchers used a global cognition score that summarizes 19 cognitive tests. The mean score ranged from 0.5 for people with no cognitive impairment to 0.2 for people with mild cognitive impairment to -0.5 for people with Alzheimer’s disease.
After adjusting for other factors that might affect the rate of memory decline, such as age, gender and smoking, the researchers found that the cognition scores of people who had the highest flavonol intake decreased at a rate of 0.4 units per decade slower than people who had the lowest intake. Holland noted that this is likely due to the flavonols’ inherent antioxidant and anti-inflammatory properties.
The study also divided the flavonol class into the four constituents: kaempferol, quercetin, myricetin and isorhamnetin. The foods that contributed the most to each category were: kale, beans, tea, spinach, and broccoli for kaempferol; tomatoes, cabbage, apples and tea for quercetin; tea, wine, cabbage, oranges and tomatoes for myricetin; pears, olive oil, wine and tomato sauce for the isorhamnetin.
People who had the highest intake of kaempferol had a rate of 0.4 units per decade slower cognitive decline than those in the lowest group. Those with the highest quercetin intake had a 0.2 unit per decade slower rate of cognitive decline than those in the lowest group. People with the highest myricetin intake had a 0.3 unit per decade slower rate of cognitive decline than 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 dietary flavonols and slower cognitive decline, but it doesn’t prove that flavonols directly cause a slower rate of cognitive decline. Among other things, the study also leads to a recovery of the qualities of red wine, rich in flavonoids, recently under attack by the European Commission.
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