The emerging science of polyphenols in aging neuroscience
By Austin Perlmutter, MD
As our bodies age, our brains age too. This isn’t necessarily bad, as we gain wisdom and experience with the passing years. However, research shows that time can take a substantial toll on various aspects of our brain function. For example, older adults are at higher risk of depression and dramatically higher risk for dementia. However, new research indicates that certain lifestyle choices, including those related to our diets may help target pathways related to brain aging. In this article, we’re exploring the role of polyphenols, a nutrient group that shows promise.
What is a polyphenol?
For most people, food is seen as comprised of calories, macronutrients (fats carbs and proteins) and micronutrients (vitamins and minerals). Yet our food also contains an incredible diversity of additional molecules. One group of these molecules that is now receiving a spotlight are called polyphenols. Polyphenols are molecules that are found in plant foods, as well as (in smaller amounts) animal foods. A wide range of research suggests that consumption of diverse polyphenol-rich food is a powerful way to support overall and brain health. This is an active area of investigation, with nearly $10 million just committed by the NIH to further study the topic.
How could polyphenols act on the brain?
In understanding how dietary nutrients may influence brain aging, researchers often start by looking at the gut, and the gut microbiome. This is especially the case for polyphenols, since they are poorly absorbed by our GI tract. Polyphenols are proposed to have several beneficial effects within the gut that could translate into downstream enhancements for the brain. For example, they may help to support the integrity of the gut lining, beneficially influence the species and abundance of bacteria in the gut, and, after being acted on by microbes, turn into metabolites that can be absorbed into the bloodstream and pass through the blood brain barrier to impact the brain.
How does this relate specifically to brain aging?
Unhealthy brain aging is believed to be driven by a host of pathways including dysregulated inflammatory signaling, vascular dysfunction, altered neuroplasticity and impaired brain energy production and utilization. Consumption of polyphenols is proposed to act on these pathways, especially by way of beneficially altering the gut microbiome composition. There’s also a recent suggestion that polyphenols may impact longevity-related pathways by way of epigenetic effects, which could have implications for brain longevity. It is notable here that most data on this theme comes from preclinical work, with only a few human studies published to date on the topic.
"Blue Zones" and Polyphenols for Brain Aging
In certain places around the world, people seem to live longer, healthier lives. These places have been dubbed "Blue Zones" by Dan Buettner, and one key characteristic of the diets in these locations (places like Loma Linda California, Sardinia Italy and Okinawa Japan appears to be consumption of polyphenol rich foods. It's even more notable that in these Blue Zones, risk for dementia appears dramatically lower than in other populations. Granted, these populations also do lots of other good things for their brains (like moving their bodies each day and living in social community!)
What are some foods that are rich in polyphenols?
Dark Chocolate - High in flavonoids, particularly catechins and procyanidins.
Berries (such as blueberries, strawberries, and blackberries) - Rich in anthocyanins and flavonoids.
Red Wine - Contains resveratrol and flavonoids.
Coffee - Packed with chlorogenic acids.
Green Tea - High in catechins like epigallocatechin gallate (EGCG).
Olives and Olive Oil - Contain hydroxytyrosol and oleuropein.
Nuts (especially walnuts and pecans) - High in flavonoids and ellagic acid.
Pomegranates - Rich in tannins and anthocyanins.
Apples - Contain flavonoids like quercetin.
Grapes (especially red and purple varieties) - High in resveratrol and anthocyanins.
Onions - Particularly rich in quercetin.
Spinach - Contains flavonoids like luteolin and kaempferol.
Cocoa - High in flavonoids, similar to dark chocolate.
Turmeric - Contains curcumin
Soybeans and Soy Products - Rich in isoflavones, a type of polyphenol.
Spices and Herbs: the most concentrated sources of any food!
Putting it Together
In general, the strongest evidence for diet as it relates to protecting the brain from unhealthy aging comes from research showing that consuming a minimally processed, whole food-based diet along the lines of the Mediterranean or MIND diet can help prevent age-related cognitive decline and dementia. These diets feature a wide range of polyphenol-rich foods including olive oil, fruits, vegetables, nuts and seeds, tea and herbs and spices, along with healthy fats and fiber.
Keep Learning!
Those polyphenol rich food are just so delicious and
wonderful to eat