Improve memory as you age with more flavonols, study says
Eating more flavonols, antioxidants found in many vegetables, fruits, tea and wine, may slow the rate of memory loss, a new study finds.
The cognitive score of people in the study who ate the most flavonols declined 0.4 units per decade more slowly than those who ate the least flavonols. The results remained even after adjusting for other factors that can affect memory, such as age, gender and smoking recently published study in Neurology, the medical journal of the American Academy of Neurology.
“It’s exciting that our study shows that certain dietary choices can lead to a slower rate of cognitive decline,” said study author Dr. Thomas Holland, an instructor in the department of internal medicine. at Rush University Medical Center in Chicago, in a statement.
“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 cytoprotective, meaning they protect cells, including neurons, so it’s possible there could be a direct effect on cognition, said Dr. David Katz, a specialist in preventive and lifestyle medicine and nutrition who was not involved in the study.
“But they’re also a marker of higher fruit and vegetable intake — which is good for the brain because it’s good for every vital organ, and the organism as a whole,” Katz said in an email.
“They can also be an indicator of better overall diet quality or even greater health awareness. People who are more health conscious may do things to preserve their cognition, or perhaps being more health conscious is a byproduct of better cognition.”
Plants contain more than 5,000 flavonoid compounds that play an important role in creating cell growth, combating environmental stress and attracting pollinating insects.
Flavonols, a type of flavonoid, have been shown in animal and some human studies to reduce inflammation, a major trigger for chronic disease, and are rich sources of antioxidants. Antioxidants fight free radicals, “highly unstable molecules that are created naturally when you exercise and when your body converts food into energy,” according to National Center for Complementary and Integrative Health, part of the National Institutes of Health.
One of the most common flavonols, quercetin, has shown promise in reducing colorectal cancer Cancer and other types of cancer, according to studies. The arc contains the highest levels — lower levels can be found in broccoli, blueberries, cauliflower, kale, leeks, spinach and strawberries.
Another common flavonol, kaempferol, it appears to inhibit the growth of cancer cells while preserving and protecting normal cells. Good sources kaempferol are onions, asparagus and berries, but the richest plant sources are spinach, kale and other green leafy vegetables, as well as herbs such as chives, dill and tarragon.
The third main player is Miricetin, who was studied in rodents to control blood sugar and reduce tau, a protein that causes tangles Alzheimer’s and other dementias. Spinach and strawberries contain high levels of myricetin, but honey, blackcurrants, grapes and other fruits, berries, vegetables, nuts and tea are also good sources.
The last group of flavonols, isorhamnet, can protect against cardiovascular and neurovascular diseases with antitumor and anti-inflammatory properties. Good sources of isorhamnetin are pears, olive oil, wine and tomato sauce.
You can find a complete list of flavonoid content in different fruits and vegetables here.
The new study asked 961 people with an average age of 81 and no signs of dementia to fill out a food questionnaire every year for seven years. In addition, the participants underwent annual cognitive and memory tests and were asked how much time they spend physically and mentally active.
People were divided into groups based on their daily intake of flavonols. The lowest intake was about 5 milligrams per day; a maximum of 15 milligrams per day—the equivalent of a cup of dark leafy greens, the study said. (By comparison, the average intake of flavonols for U.S. adults is about 16 to 20 milligrams per day, according to the study.)
The study looked at the effect of four major flavonols – kaempferol, quercetin, myricetin and isorhamnetin – on the rate of cognitive decline over seven years.
The biggest effect was found with kaempferol: People who ate the highest amounts of foods with kaempferol showed a 0.4 unit per decade slower rate of cognitive decline compared to those who ate the least, according to the study.
Myricetin was as follows: People who ate the most myricetin foods had a 0.3 unit per decade slower rate of cognitive decline compared to the group who consumed the least. People who ate the most foods with quercetin showed a 0.2 unit per decade slower rate of cognitive decline.
Isorhamnetin in the diet had no effect, the study showed.
Despite the obvious positives, studies on the impact of flavonols on human health have not produced conclusive results – mainly because many have been observational and cannot show direct cause and effect. This also applies to the neurological study, according to its authors.
Several randomized controlled trials—the scientific gold standard—have shown benefits associated with flavonols for blood sugar control in type 2 diabetes and improving cardiovascular health, according to the Linus Pauling Institutehome for Information Center for Micronutrientsonline database for nutrition information.
It is not known whether these benefits are long-term, the institute said, and no clear effect on cancer prevention or cognitive protection has been demonstrated.
“There are other bioactive substances that may contribute to the observed outcomes,” Katz said. “Further studies are needed to fully isolate the effects of flavonoids.”
There’s also a downside to assuming health effects without the necessary studies to back them up, said Dr. Christopher Gardner, a medical researcher and director of the Nutrition Studies Research Group at Stanford University.
“You can count on Americans wanting the benefits of plants but not eating them,” he said in an email.
“(What) if people read the headline and rush out and buy bottled flavonols (extracted) instead of eating whole plant foods, and it turns out it wasn’t just flavonols, but a package of everything in those plants (instead).”