Flavonoid-Rich Fruits – The New Brain Superfood?

A delicious and natural way to improve your mental health? 

May is Mental Health Awareness Month, which means it’s time to turn our attention toward accessible, actionable, evidence-based dietary strategies that can have multiple meaningful impacts on our brains.

This brings Flavonoids to the forefront. 

Flavonoids are a family of phytochemical compounds that exist in a wide array of plant-origin foods.

They’ve been on my radar in recent times as evidence around their inclusion has been increasingly linked with improved mental health outcomes in various areas.

While there are six main families of flavonoids, the two we will focus on today are:

Flavanones –  Lemon, lime, grapefruit, mandarins, tomato, oranges* and orange juice.

Anthocyanidins – Purple Sweet Potato, red cabbage, blueberry*, blackberry, cranberry, red onion, raspberry, strawberry, plums, red beans, red onion, red radish, black beans, grapes, pomegranate.

*These are the food sources providing the most of each compound in the average diet.

Let’s find out why.

Flavonoids & Subjective Cognitive Decline

Subjective Cognitive Decline, as per the CDC, is defined as the self-reported worsening of confusion and/or memory loss over time.

It affects around 1 in 9 adults over the age of 45 and is considered one of the earliest recognizable symptoms of dementia and Alzheimer’s disease.

This is where flavonoids, and specifically flavonoid-rich fruits, come into play.

In 2021, the Neurology journal published the results of an observational study looking at around 75,000 adults over a 15-year period to determine whether or not their total flavonoid intake was related to subjective cognitive decline.

They found that individuals with the highest intakes of flavanones and anthocyanins retained the most cognitive functionality over time.

This wasn’t the only meaningful study to find results of this nature though.

In the same year, BMC Medicine published a very intriguing study looking at female twins over a 10-year period and found that the twin with a higher intake of flavanones and anthocyanins had better age-related cognitive test scores, with anthocyanins specifically being correlated with larger left hippocampal volume (an area of the brain associated with memory, tends to shrink over time).

The gap in flavonoid intake required to gain the brain health benefits in the study above was approximately an additional two oranges (flavanones) and 1 cup of blueberries (anthocyanins) per day.

This equates to an additional 4 servings of flavonoid-rich fruits daily, a dietary change that is within reach for those who are compelled to bolster their brain health.

But wait a minute, what is it about flavonoids that might explain these very compelling results?

Let’s explore that next.

The Unique Brain Benefits Of Flavonoids

I’ve been aware for some time that flavonoids were pegged by scientists as potentially having unique brain health benefits because early evidence has suggested they have a protective, anti-inflammatory effect on neurons (brain cells) by promoting the creation of anti-inflammatory compounds and suppressing the creation of pro-inflammatory ones.

There are at least two additional explanations as to why they are so helpful:

1. They interact with cellular signaling pathways in such a way that allows brain cells to live longer and reproduce more than they might otherwise. 
2. They improve blood flow to the brain which supports the growth of new blood vessels and nerve cells.

But the effects on brain cell inflammatory status is the one of greatest interest today because:

Neuroinflammation is considered a big driver of brain-related conditions including Alzheimer’s Disease, Parkinson’s disease, depression, and stroke. 

This scientific reality makes sense of the findings discussed so far and also opens the door to a discussion of the role of flavonoids in the world of depression.

Flavonoid Intake & Depression Risk

Cognitive decline is a very relevant public health issue, but by its nature may not be as compelling a consideration for the younger demographic.

Precisely why it is equally important for me to also discuss the state of the science around flavonoid intake and depression in this piece.

The Antioxidants journal conducted a meta-analysis of studies looking at the relationship between flavonoid intake and depressive symptoms, with results indicating that a higher flavonoid intake may be protective/reductive as it relates to these symptoms. 

Even more intriguing were the results of a 2022 paper from Translational Psychiatry which found that individuals with the highest intake of flavonoid-rich foods in midlife had the lowest risk of being clinically diagnosed with depression later in life. 

The promise from these observational studies has thus far been supported in a limited capacity by randomized human trials in populations like young males and new mothers where flavonoid-based interventions have demonstrated improvements in mental health outcomes.

Final Thoughts

Insofar as one’s diet can contribute positively to mental health and cognition, it seems clear to me that an emphasis on the daily and diverse consumption of flavonoid-rich fruits is a low-risk, high-reward scenario for anyone to pursue as they look towards the betterment of their dietary pattern.

1. _{Sources of flavonoids in the U.S. diet using USDA’s updated. (n.d.). Retrieved May 3, 2023, from https://www.ars.usda.gov/ARSUserFiles/80400525/Articles/AICR06_flav.pdf} 
2. _{Centers for Disease Control and Prevention. (2019, February 27). Subjective cognitive decline - a public health issue. Centers for Disease Control and Prevention. Retrieved May 3, 2023, from https://www.cdc.gov/aging/data/subjective-cognitive-decline-brief.html} 
3. _{Yeh, T. S., Yuan, C., Ascherio, A., Rosner, B. A., Willett, W. C., & Blacker, D. (2021). Long-term Dietary Flavonoid Intake and Subjective Cognitive Decline in US Men and Women. Neurology, 97(10), e1041–e1056. https://doi.org/10.1212/WNL.0000000000012454} 
4. _{Jennings, A., Steves, C. J., Macgregor, A., Spector, T., & Cassidy, A. (2021). Increased habitual flavonoid intake predicts attenuation of cognitive ageing in twins. BMC medicine, 19(1), 185. https://doi.org/10.1186/s12916-021-02057-7}
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6. _{Chen, Y., Peng, F., Xing, Z., Chen, J., Peng, C., & Li, D. (2022). Beneficial effects of natural flavonoids on neuroinflammation. Frontiers in immunology, 13, 1006434. https://doi.org/10.3389/fimmu.2022.1006434} 
7. _{Ali, S., Corbi, G., Maes, M., Scapagnini, G., & Davinelli, S. (2021). Exploring the Impact of Flavonoids on Symptoms of Depression: A Systematic Review and Meta-Analysis. Antioxidants (Basel, Switzerland), 10(11), 1644. https://doi.org/10.3390/antiox10111644} 
8. _{Narita, Z., Nozaki, S., Shikimoto, R., Hori, H., Kim, Y., Mimura, M., Tsugane, S., & Sawada, N. (2022). Association between vegetable, fruit, and flavonoid-rich fruit consumption in midlife and major depressive disorder in later life: the JPHC Saku Mental Health Study. Translational psychiatry, 12(1), 412. https://doi.org/10.1038/s41398-022-02166-8} 
9. _{Choi, J., Kim, J. H., Park, M., & Lee, H. J. (2022). Effects of Flavonoid-Rich Orange Juice Intervention on Major Depressive Disorder in Young Adults: A Randomized Controlled Trial. Nutrients, 15(1), 145. https://doi.org/10.3390/nu15010145} 
10. _{Barfoot, K. L., Forster, R., & Lamport, D. J. (2021). Mental Health in New Mothers: A Randomised Controlled Study into the Effects of Dietary Flavonoids on Mood and Perceived Quality of Life. Nutrients, 13(7), 2383. https://doi.org/10.3390/nu13072383}