Want to help maintain your brainpower as you grow older? Findings from new research reported in the American Academy of Neurology journal, Neurology, suggests that a higher intake of flavonoids, a class of often colorful compounds that occur in plants—may be protective of brain health.

"The long preclinical phase of dementia may be a critical window for prevention," noted authors Tian-Shin Yeh, MD, PhD, and colleagues. "Among the modifiable risk factors for cognitive decline, diet has received growing attention."

"There is mounting evidence suggesting flavonoids are powerhouses when it comes to preventing your thinking skills from declining as you get older," commented coauthor Walter Willett, MD, DrPH, of Harvard University. "Our results are exciting because they show that making simple changes to your diet could help prevent cognitive decline."

What are flavonoids?

Flavonoids are metabolites that perform a variety of functions in plants. Most of us are aware that plant foods are a source of vitamins and minerals, contain little in the way of fat and are loaded with fiber. However, there is a growing awareness of the importance of vegetables and fruit as an abundant source of flavonoids. Flavonoids have antioxidant activity and provide other beneficial effects in human health.

Flavonoids are classified into 12 major subclasses of flavonoids. The six flavonoids that have the greatest dietary significance include:

• Anthocyanins

• Flavan-3-ols

• Flavanones

• Flavones

• Flavonols

• Isoflavones

Do flavonoids help memory and cognition?

Findings from the current investigation support a benefit for greater flavonoid intake in the maintenance of cognitive function.

The study included 49,493 women who participated in the Nurses' Health Study (NHS) from 1984 to 2006 and 27,842 men enrolled in the Health Professionals Follow-Up Study (HPFS) from 1986 to 2002. The women were an average of 48 years of age and the men's age averaged 51 years at the beginning of the study.

Responses to dietary questionnaires administered during two decades of follow-up provided information concerning flavonoid intake. Cognitive function was assessed in 2012 and 2014 in NHS participants and in 2008 and 2012 in HPFS enrollees.

Questions asked of the participants to evaluate brain health by scoring cognitive function included:

• Do you have more trouble than usual remembering recent events?
• Do you have more trouble than usual remembering a short list of items, such as a shopping list?
• Do you have trouble remembering things from one second to the next?
• Do you have any difficulty in understanding things or following spoken instructions?
• Do you have more trouble than usual following a group conversation or a plot in a TV program due to your memory?
• Do you have trouble finding your way around familiar streets?

Risk factors for having an unfavorable subjective cognitive decline score:

• Heavy smoking

• Cardiovascular disease

• High blood pressure

• High blood cholesterol

• Depression

• Type 2 diabetes

• A genetic factor

Having a higher intake of total flavonoids was associated with a lower risk of developing subjective cognitive impairment during two decades of follow-up. Among men and women whose flavonoid intake was among the top 20% of combined participants (whose flavonoid intake averaged 600 milligrams per day), the risk of subjective cognitive impairment was 19% lower than those whose intake was among the lowest 20% (who had an average intake of 150 milligrams per day).

To get an idea about what you would have to consume to obtain 600 milligrams per day of flavonoids, a 100 gram serving of strawberries contains 180 milligrams. That would require approximately 330 grams of strawberries daily!

What are the best flavonoids to boost your thinking skills?

When individual foods were examined, flavones, which occur in orange or yellow vegetables and fruits, as well as in certain spices, had the strongest beneficial effects of all types of flavonoids. Flavanones and anthocyanidins also had significant effects.

Men and women whose flavone intake placed them among the top 20% of all subjects had a risk of developing subjective cognitive impairment that was 38% lower than those among the lowest 20%. The researchers also found significant associations between a lower risk of subjective cognitive decline and greater intake of specific high flavonoid foods such as:

• Orange juice

• Oranges

• Peppers

• Celery

• Grapefruit

• Grapefruit juice

• Apples/pears

• Blueberries

• Strawberries

On the topic of strawberries, it was noted that the fruit is a significant source of a flavonoid known as fisetin, which has antioxidant, anti-inflammatory and neuroprotective effects that could help lower the risk of cognitive decline. However, the intake of this flavonoid was not calculated in the current analysis.

What food has more flavonoids?

Berries are among the best sources of flavonoids. Flavonoids are also abundant in:

• Apples

• Pears

• Bananas

• Celery

• Cherries

• Cocoa

• Grapefruit

• Oranges

• Peppers

• Red wine

• Tea (especially green tea)

"The people in our study who did the best over time ate an average of at least half a serving per day of foods like orange juice, oranges, peppers, celery, grapefruits, grapefruit juice, apples and pears," Dr. Willett reported. "While it is possible other phytochemicals are at work here, a colorful diet rich in flavonoids--and specifically flavones and anthocyanins—seems to be a good bet for promoting long-term brain health."

"And it's never too late to start," he added, "Because we saw those protective relationships whether people were consuming the flavonoids in their diet 20 years ago, or if they started incorporating them more recently."

References

• American Academy of Neurology. "Adding color to your plate may lower risk of cognitive decline." Neurology, Science Daily, July 2021, https://www.sciencedaily.com/releases/2021/07/210729122215.htm
• Brennan, Dan. "Top Foods High in Flavonoids." WebMD, October 2020, https://www.webmd.com/diet/foods-high-in-flavonoids#1
• Currais A et al. J Gerontol A Biol Sci Med Sci.2018;73:299-307.
• Higdon J. "Flavonoids." Linus Pauling Institute Micronutrient Information Center. Reviewed 2016 Feb. https://lpi.oregonstate.edu/mic/dietary-factors/phytochemicals/flavonoids
• Schroeter H et al. Proc Natl Acad Sci U S A. 2006 Jan 24;103(4):1024-9.
• Spencer, Jeremy, P E. "The impact of fruit flavonoids on memory and cognition." Br J Nutr., October 2010, https://pubmed.ncbi.nlm.nih.gov/20955649/
• Yeh, Tian-Shin et al. "Long-term Dietary Flavonoid Intake and Subjective Cognitive Decline in US Men and Women." Neurology, July 2021, https://n.neurology.org/content/early/2021/07/28/WNL.0000000000012454
• Yeh TS et al. Neurology. 2021 Jul 28; 10.1212/WNL.0000000000012454.

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