Can this simple dietary change save your brain?

By John James
Published May 27, 2020

Key Takeaways

Dementia mostly affects senior citizens, but it’s a major public health challenge for everyone. Ten million new cases are reported each year, with the global cost of care expected to reach $2 trillion by 2030. While there’s no cure or surefire treatment to slow the progression of dementia, new research suggests that a change in diet could help stave off its effects.

Recent findings indicate that flavonoids, which are among the most abundant micronutrients present in plant foods, play a powerful role in protecting the brain from dementia. Common dietary sources of flavonoids include citrus fruits, apples, berries, onions, soybeans, legumes—and even chocolate and wine. A growing body of evidence suggests that these natural substances interact with the components of the brain that control memory. But there’s no consensus on how beneficial these plant compounds are, or whether it’s possible to actually consume too many flavonoids.

Brain benefits from flavonoids

Flavonoids are considered a key component in pharmaceutical and medicinal applications because of their known antioxidative, anti-inflammatory, antimutagenic, and anticarcinogenic properties. The most recent data on different plant metabolites suggests that flavonoids interact with receptor systems of the brain, stimulating neuronal regeneration, scavenging free radicals, and preventing neuronal dysfunction.

A recent study published in The American Journal of Clinical Nutrition examined the relationship between dietary flavonoid intake and the risk of Alzheimer disease and related dementias (ADRD). The study used participant data from the Framingham Heart Study, which documented the chronic disease risk factors of 5,000 adults over 2 decades. Of the 2,800 participants who qualified for the latest study, all completed dietary assessments over the course of a year.

Results indicated that individuals with the highest intakes of flavonoids had a lower risk of ADRD vs individuals with the lowest flavonoid intakes.

The authors concluded: “Our findings imply that higher long-term dietary intakes of flavonoids are associated with lower risks of ADRD and AD in US adults.”

These findings support an earlier study that analyzed the dietary intake of participants in the Nurses’ Health Study—one of the largest ongoing investigations into the risk factors for major chronic diseases in women. After measuring the cognitive function of 16,000 participants, the researchers concluded that greater intakes of blueberries and strawberries—high-flavonoid foods—were associated with slower rates of cognitive decline.

Body benefits from flavonoids

Epidemiological studies have also reported that flavonoid-rich diets are associated with a reduced risk of cardiovascular diseases, diabetes, and some types of cancers. For example, researchers followed the health and diet of 56,000 Danish adults for 23 years to investigate the correlation between flavonoid intake and heart disease and cancer. The study, published in Nature Communications, confirmed that a moderate habitual intake of flavonoids is inversely correlated with all-cause, cardiovascular disease-related, and cancer-related mortality. Notably, these associations plateaued at flavonoid intakes of 500 mg a day.

“The strongest associations observed between flavonoids and mortality was in smokers and high alcohol consumers, with higher intakes being more beneficial,” the authors wrote. “These findings highlight the potential to improve population health through dietary recommendations to ensure adequate consumption of flavonoid-rich foods, particularly in these high-risk populations.”

The idea that flavonoid consumption leads to greater health overall is well supported, both in scientific literature and popular culture. For instance, flavonoid-rich foods are staples of the Mediterranean diet, a way of eating that focuses on fruits, vegetables, and whole grains. The Mediterranean diet is not only consistently ranked the best diet overall by U.S. News & World Report, but is also linked to better cognitive function and lower risk of cognitive decline in older adults.

Are flavonoids all they’re cracked up to be?

Although the research bends strongly in favor of flavonoids, some findings recommend being careful about how often you ingest these plant compounds. Existing research notes that the potential toxic effects of excessive flavonoid intake have been understudied.

An analysis of the health impacts of flavonoids suggests that the compounds can act as mutagens at higher doses, which means they generate free radicals and inhibit key enzymes involved in hormone metabolism.

“Thus, in high doses, the adverse effects of flavonoids may outweigh their beneficial ones, and caution should be exercised in ingesting them at levels above that which would be obtained from a typical vegetarian diet,” the authors wrote. “This suggests that unregulated, commercially available flavonoid-containing supplements may have biologic activity that can adversely affect human health.”

In addition, flavonoids have the potential to interact with prescription drugs. A flavonoid found in grapefruit, for example, has been identified as interfering with medications such as calcium channel blockers, immunosuppressants, and antihistamines—inhibiting their potency.

Flavonoids can help fight dementia

While researchers agree that there is still much to learn about flavonoids, including determining their optimal level of consumption, it’s clear that a flavonoid-rich diet is beneficial for the body and brain. As research advances, more will be known about the specific interactions of flavonoids and cognitive function, but until then there is an added advantage to increasing the fruits and vegetables in your diet: investing in your health and mind.

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