Filling up on flavonols may slow down memory loss, study finds

If you rarely eat kale, watercress, and arugula, consider making these leafy greens part of your regular diet.

Thanks to the flavonol content, which is an antioxidant found in certain plant foods, it helps to preserve memory as we age. This is according to a recent study from Rush University Medical Center in Chicago.

These new findings add to the evidence that dietary flavonols are beneficial for brain health.

Breakdown of flavonoids and flavonols

Flavonols belong to one of the six major subclasses of flavonoids, a large family of over 5,000 phytochemicals found in vegetables, fruits, teas, cocoa, herbs, red wine, soybeans, and legumes.

Foods such as onions, kale, broccoli, parsley, apples, blueberries, and tea contain four flavonol compounds: quercetin, kaempferol, myricetin, and isorhamnetin.

Like many flavonoids, flavonols have powerful antioxidant and anti-inflammatory properties that can reduce cell damage and reduce inflammation throughout the body, including the brain.

Previous studies have found that high flavonoid intake slows cognitive decline and reduces the risk of Alzheimer’s disease. However, limited research has investigated associations between specific subclasses of flavonoids, such as flavonols, and cognitive function.

Do flavonols delay memory loss?

A new study published online November 22 in the journal Neurology investigated the relationship between dietary intake of total and individual flavonols and cognitive decline in older adults.

The study included data from 961 community-dwelling Chicago residents enrolled in the ongoing Rush Memory Aging Project. Participants had an average age of 81 at the start of the study and had no dementia.

Over a period of 7 years, participants underwent cognitive testing that included a series of 19 tests each year. An overall cognitive score was determined for each participant based on test performance.

Participants also provided detailed dietary information and were asked annually about other factors related to lifestyle and cognitive status.

Those with the highest flavonol intake (15 mg/day) had a 32% reduction in cognitive decline compared to those with the lowest intake (5 mg/day). 15 milligrams of flavonols is equivalent to about 1 cup of leafy greens.

When researchers looked at specific flavonols, they found that higher intakes of quercetin, kaempferol, and myricetin slowed memory loss.

These findings suggest that researchers could influence the rate of memory decline by factors such as age, education, participation in mentally-relevant activities, physical activity, smoking status, cardiovascular health, and other dietary components. It did not change when I explained the factors that contributed to it.

strengths and cautions

One of the strengths of this study is that it used a trained technician to objectively assess cognitive performance. Previous studies investigating flavonoids and cognition relied on subjective assessments of cognition.

Similarly, measurements of cognitive function, diet, and other risk factors were performed annually throughout the study to support the reliability of the findings.

The main limitation is that the study was an observational study rather than a randomized controlled trial. As such, the findings do not prove that eating large amounts of flavonol-rich foods slows cognitive decline over time.

This study also used error-prone self-reported dietary information.

Still, the findings are consistent with other studies linking higher dietary intakes of flavonoids and flavonols to improved cognitive health and protection against Alzheimer’s disease.

Discovery of flavonols

In this study, the main food contributors of quercetin were tomatoes, kale, apples, and tea. Other good sources include blueberries, arugula, red onions, green onions (scallions), watercress, and cowpeas.

Participants with the highest intake of quercetin consumed an average of 10 milligrams daily. This amount is found in 1 cup of blueberries, 2 cups of black tea, or 1 cup of green tea and 1 cup of raw kale.

As for kaempferol, the main food sources were kale, beans, tea, spinach and broccoli. Watercress, black and green tea also contain significant amounts.

High kaempferol consumers averaged 3.7 milligrams in their daily diet, equivalent to 0.5 cups of watercress, 1 cup of raw spinach, or 1 cup of tea.

Good sources of myricetin include blueberries, parsley, and green tea. The highest intake participants consumed approximately 1 milligram daily. It is found in 2 tablespoons of fresh parsley, 1/2 cup of blueberries, or 1/2 cup of green tea.

To increase your intake of flavonoids, reach for whole foods rather than supplements. It’s also a great source of vitamins, minerals, and other phytochemicals needed for healthy brain aging.

Toronto-based private practice dietician Leslie Beck is Medcan’s Director of Food and Nutrition. follow her on her twitter @LeslieBeckRD

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