Individuals who eat or drink more foods with the antioxidant flavonol
, which is found in nearly all fruits and vegetables as well as tea, may be less likely to develop Alzheimer's dementia
years later, according to a study published in the January 29, 2020, online issue of Neurology
, the medical journal of the American Academy of Neurology.
Study author Dr Thomas M. Holland, MD, of Rush University in Chicago told Thailand Medical
News, "More research is needed to confirm these results, but these are promising findings. Eating more fruits and vegetables and drinking more tea could be a fairly inexpensive and easy way for people to help stave off Alzheimer's dementia
. With the elderly population increasing worldwide, any decrease in the number of people with this devastating disease, or even delaying it for a few years, could have an enormous benefit on public health."
are a type of flavonoid, a group of phytochemicals found in plant pigments known for its beneficial effects on health.
The research study involved 921 people with an average age of 81 who did not have Alzheimer's dementia
. The people filled out a questionnaire each year on how often they ate certain foods. 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 such as reading and playing games.
The research participants were tested yearly to see if they had developed Alzheimer's dementia
. They were followed for an average of six years. The researchers used various tests to determine that 220 people developed Alzheimer's dementia
during the study.
The participants were divided into five groups based on how much flavonol
they had in their diet. The average amount of flavonol
intake in US adults is about 16 to 20 milligrams per day. In the study, the lowest group had intake of about 5.3 mg per day and the highest group consumed an average of 15.3 mg per day.
The research found that people in the highest group were 48 percent less likely to later develop Alzheimer's dementia
than the people in the lowest group after adjusting for genetic predisposition and demographic and lifestyle factors. Of the 186 people in the highest group, 28 people, or 15 percent, developed Alzheimer's dementia
, compared to 54 people, or 30 percent, of the 182 people in the lowest group.
The study results were the same after researchers adjusted for other factors that could affect the risk of Alzheimer's dementia
, such as, diabetes, previous heart attack, stroke and high blood pressure.
The research also broke the flavonols
down into four types: isorhamnetin, kaempferol, myricetin and quercetin. The top food contributors for each category were: pears, olive oil, wine and tomato sauce for iso
rhamnetin; kale, beans, tea, spinach and broccoli for kaempferol; tea, wine, kale, oranges and tomatoes for myricetin; and tomatoes, kale, apples and tea for quercetin.
Individuals who had high intake of isorhamnetin were 38 percent less likely to develop Alzheimer's
. Those with high intake of kaempferol were 51 percent less likely to develop dementia
. And those with high intake of myricetin were also 38 percent less likely to develop dementia
. Quercetin was not tied to a lower risk of Alzheimer's dementia
Dr Holland noted that the study shows an association between dietary flavonols
risk but does not prove that flavonols
directly cause a reduction in disease risk.
The researchers mentioned that other limitations of the study are that the food frequency questionnaire, although valid, was self-reported, so people may not accurately remember what they eat, and the majority of participants were white people, so the results may not reflect the general population.
Reference: Dietary flavonols and risk of Alzheimer dementia
Thomas M. Holland, Puja Agarwal, Yamin Wang, View ORCID ProfileSue E. Leurgans, David A. Bennett, Sarah L. Booth, Martha Clare Morris, Neurology Journal, First published January 29, 2020, DOI: https://doi.org/10.1212/WNL.0000000000008981