Improve memory as you age by eating more flavonols, study says

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Improve memory as you age by eating more flavonols, study says



CNN

Eating more flavonols, antioxidants found in many vegetables, fruits, tea and wine, may slow your rate of memory loss, a new study finds.

The cognitive value of the people in the study who ate the most flavonols declined 0.4 units per decade more slowly than those who ate the fewest flavonols. The results held even after accounting for other factors that can affect memory, such as age, gender and smoking, according to the study recently published in Neurology, the medical journal of the American Academy of Neurology.

“It’s exciting that our study shows that making specific dietary choices can lead to slower 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 fruits and vegetables and drinking more tea is an easy way for people to take an active role in maintaining their brain health.”

Flavonols are cytoprotective, meaning they protect cells, including neurons, so it’s plausible that there might be a direct impact on cognition, said Dr. David Katz, a preventive and lifestyle medicine and nutrition specialist who was not involved with the study.

“But they’re also a marker for higher fruit and vegetable intake — which is good for the brain because it’s good for every vital organ and the whole organism,” Katz said in an email.

“They can also be an indication of an overall better diet quality or even greater health awareness. People who are more health conscious can do things to maintain their cognition, or maybe more health conscious behavior is a byproduct of better cognition.”

Plants contain over 5,000 flavonoid compounds that play a role in generating cell growth, combating environmental stress and attracting insects for pollination.

Flavonols, a type of flavonoid, have been shown in animal and some human studies to reduce inflammation, a major trigger of chronic disease, and are a rich source of antioxidants. Antioxidants fight free radicals, “highly unstable molecules that are formed naturally when you exercise and when your body converts food into energy,” according to the 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 the incidence of colorectal disease Cancer and other cancers, according to studies. Onions contain the highest levels — lower levels are found in broccoli, blueberries, cauliflower, kale, leeks, spinach, and strawberries.

Another common flavonol, kaempferol, appears to inhibit the growth of cancer cells while normal cells are preserved and protected. Good sources of kaempferol include onions, asparagus, and berries, but the richest plant-based sources are spinach, kale, and other leafy greens, as well as herbs like chives, dill, and tarragon.

A third key player is myricetin, which has been studied in rodents to control blood sugar and reduce tau, a protein that causes the hallmark entanglements of Alzheimer’s and other dementias. Spinach and strawberries are high in myricetin, but honey, blackcurrants, grapes and other fruits, berries, vegetables, nuts, and tea are also good sources.

The last group of flavonols, isorhamnetin, may protect against cardiovascular and neurovascular disease in addition to antitumor and anti-inflammatory benefits. Good sources of isorhamnetin include pears, olive oil, wine, and tomato sauce.

A complete list of the flavonoid content of various fruits and vegetables can be found here.

The new study asked 961 people, with an average age of 81 and no evidence of dementia, to complete a diet questionnaire every year for seven years. In addition, participants underwent annual cognitive and memory tests and were asked about their time spent in physical and mental activity.

People were divided into groups based on their daily intake of flavonols. The lowest intake was about 5 milligrams per day; the highest 15 milligrams per day — the equivalent of about a cup of dark leafy greens, the study found. (For comparison, according to the study, the average flavonol intake among U.S. adults is about 16 to 20 milligrams per day.)

The study examined the impact of the four major flavonols – kaempferol, quercetin, myricetin and isorhamnetin – on the rate of cognitive decline over the seven years.

The greatest effect was seen with kaempferol: people who ate the highest amounts of foods containing kaempferol showed a 0.4 units per decade slower rate of cognitive decline compared to those who ate the least.

Next came myricetin: People who ate the most foods with myricetin had a 0.3 units per decade slower rate of cognitive decline compared to the lowest consumption group. People who ate the most foods with quercetin showed a 0.2 units per decade slower rate of cognitive decline.

Dietary isorhamnetin had no effect, according to the study.

Despite the apparently positive results, studies on the effects of flavonols on human health have been inconclusive – mainly because many are observational and cannot show direct cause and effect. According to the authors, this also applies to the neurology study.

Some randomized controlled trials – the scientific gold standard – have shown benefits associated with flavonols for controlling blood sugar in type 2 diabetes Improving cardiovascular health, according to the Linus Pauling Institute, home of the Micronutrient Information Center, an online database of nutritional information.

It’s not known if these benefits are long-term, the institute said, and no clear effects on cancer prevention or cognitive protection have been shown.

“There are other bioactives that may contribute to the observed results,” Katz said. “Additional studies are needed to fully isolate the flavonoid action.”

There’s also a downside to assuming a health effect without the necessary studies to back it up, said Dr. Christopher Gardner, research professor of medicine and director of the Nutrition Studies Research Group at Stanford University.

“You can rest assured that Americans want the benefits of plants, but don’t want to eat them,” he said in an email.

“(What) if people read the headline and ran and bought bottled (extracted) flavonols instead of eating whole plant foods, and it turns out it wasn’t just the flavonols, it was the package of everything in those plants (instead ).”

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