Flavonoids in fruits, vegetables and wine may slow rate of memory loss, study shows

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

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

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

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Flavonols are cytoprotective, meaning they protect cells, including neurons, so it’s plausible that there’s a direct impact on cognition, explains David Katz, an expert in preventive medicine and lifestyle and nutrition who wasn’t 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 all the vital organs and the body as a whole,” Katz said in an email.

“They can also be a marker of better overall diet quality or even greater health awareness. More health-conscious people might do things to preserve their cognition, or perhaps being more health conscious is a by-product of better cognition.”

A huge family of phytochemicals

Plants contain over 5,000 flavonoid compounds, which play roles in producing 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 for chronic disease, and are rich sources 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 onset of colorectal and other cancers, according to studies. Onions contain the highest levels – lowest levels can be found in broccoli, blueberries, cauliflower, kale, leeks, spinach and strawberries.

Another common flavonol, kaempferol, appears to inhibit cancer cell growth while preserving and protecting normal cells. Good sources of kaempferol are onions, asparagus, and berries, but the richest vegetable sources are spinach, kale, and other green leafy vegetables, as well as herbs such as chives, dill, and tarragon.

A third major player is myricetin, which has been studied in rodents for blood sugar control and reduction of tau, a protein that causes the tangles characteristic of Alzheimer’s disease and other dementias. Spinach and strawberries contain high levels of myricetin, but honey, black currants, grapes and other fruits, berries, vegetables, nuts and tea are also good sources.

The last group of flavonols, called isorhamnetin, may protect against cardiovascular and neurovascular disease, as well as antitumor and anti-inflammatory benefits. Good sources of isorhamnetin are pears, olive oil, wine and tomato sauce.

You can find a complete list of the flavonoid content of various fruits and vegetables here🇧🇷

An older, dementia-free population

The new study asked 961 people with an average age of 81 and no signs of dementia to fill out a dietary questionnaire each year for seven years. In addition, participants underwent annual cognitive and memory tests and were asked about the time they spent being physically and mentally active.

People were divided into groups based on their daily intake of flavonoids. 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 noted. For comparison, the average flavonol intake in US adults is about 16 to 20 milligrams per day, according to the study.

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

The biggest impact was found with kaempferol: People who ate the highest amounts of kaempferol foods had a rate of cognitive decline 0.4 units per decade slower compared to those who ate the least, according to the study.

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

Dietary isorhamnetin had no impact, the study found.

inconclusive impacts

Despite apparent positives, studies on the impact of flavonols on human health have been inconclusive – mainly because many are observational and cannot show direct cause and effect. This also applies to the study of Neurology, according to its authors.

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

Whether these benefits are long-term is unknown, the institute said, and no clear impact has been demonstrated on cancer prevention or cognitive protection.

“There are other bioactives that may contribute to the observed results,” said Katz. “Further studies are needed to fully isolate the effects of flavonoids.”

There’s also a downside to assuming a health impact 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 count on Americans wanting the benefits of plants but not wanting to eat them,” he said in an email.

“What if people read the headline and ran out to buy bottled (extracted) flavonols instead of eating whole plant foods, and found out that it’s not just the flavonols, but the package of everything in those plants (instead)?”

Source: CNN Brasil

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