Herbs, spices, grains, legumes, nuts, fruit, berries, vegetables are rich in chemical compounds: polyphenols. Diets rich in polyphenols provide better long-term health outcomes, there is a growing body of evidence for their beneficial effects and role in combating Alzheimer's, cognitive decline and dementia.
An Overview of Polyphenols and Cognitive Health
A higher intake of polyphenol, especially flavonoids, is consistently associated with better cognitive outcomes and a reduced risk of cognitive decline and dementia.
Among the flavonoid subclasses, anthocyanins (found in berries) were the most studied, showing significant anti-neuroinflammatory effects. Other flavonoid classes, including flavan-3-ols, flavonols (spinach, kale, and broccoli), flavanones (in citrus fruits) and flavones, also demonstrate cognitive benefits, largely through their antioxidant and anti-inflammatory properties which support vascular integrity, crucial for maintaining brain health.
Flavonoids, found in fruits, vegetables, and plant-based foods, may enhance cognitive function by modulating cellular signaling pathways, regulating antioxidant enzymes and reducing inflammation. Anthocyanins, in particular, inhibit key inflammatory mediators contributing to their neuroprotective effects. These compounds also counteract neuronal death caused by oxidative stress and neuroinflammation while inhibiting amyloid β aggregation, a hallmark of Alzheimer’s disease.
Other polyphenols, such as phenolic acids and lignans, though less extensively studied, also show potential cognitive benefits. Lignans, found in whole grains and seeds (especially flaxseed), have weak estrogenic effects and may protect neurons and improve memory by reducing inflammation, preventing cell death, and regulating synaptic plasticity. They may also function as epigenetic modifiers, influencing gene expression related to learning and memory.
Phenolic acids, commonly found in foods like coffee, tea, apples, and nuts, are associated with a lower risk of cognitive decline. Studies on walnuts, coffee, and tea consumption although the effects on established cognitive impairment remain unclear.
To see the collection of studies (that we will add to when new research is published), scroll down to bottom of page. If you have any suggestions of other studies to include, add them in the Comments section, also at bottom of page.
Polyphenols are not a magic pill. Polyphenol rich foods should be part of a healthy eating pattern and lifestyle.
To get the benefits of polyphenols, we enjoy using a whole food approach. What does this mean? At a minimum, enjoying fruit, nuts and seeds on a daily basis. Consuming herbs and spices. Prioritising as wide variety of foods as possible, including vegetables, whole grains and legumes. A polyphenol rich diet supports health across multiple areas, so don't overthink what to eat.
Benefits come from daily eating, daily living - over the course of time. Some may prefer a Western, Mediterranean diet; others a similarly plant forward Asian diet.
Be wary of using supplements where the evidence, safety, quality of manufacture or formulation is not as strong as the marketing behind them. As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment.
Have specific polyphenol questions? Try the online Phenol-Explorer. The database "contains more than 35,000 content values for 500 different polyphenols in over 400 foods. These data are derived from the systematic collection of more than 60,000 original content values found in more than 1,300 scientific publications."
Stay Healthy,
Alastair
Scroll down to see the studies.
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Alzheimer's, Brain Health, Cognition and Dementia
Fanelli Kuczmarski M, Crawford SB, Sebastian RS, Beydoun MA, Goldman JD, Moshfegh AJ, Evans MK, Zonderman AB. Association between Flavonoid Intake and Cognitive Executive Function among African American and White Adults in the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) Study. Nutrients. 2024 Apr 30;16(9):1360. doi: 10.3390/nu16091360. PMID: 38732605; PMCID: PMC11085386.
Jennings A, Thompson AS, Tresserra-Rimbau A, O'Neill JK, Hill C, Bondonno NP, Kühn T, Cassidy A. Flavonoid-Rich Foods, Dementia Risk, and Interactions With Genetic Risk, Hypertension, and Depression. JAMA Netw Open. 2024 Sep 3;7(9):e2434136. doi: 10.1001/jamanetworkopen.2024.34136. PMID: 39292460; PMCID: PMC11411383.
Lyu, C., Jacques, P.F., Doraiswamy, P.M. et al. Flavonoid-Rich Fruit Intake in Midlife and Late-Life and Associations with Risk of Dementia: The Framingham Heart Study. J Prev Alzheimers Dis (2024). https://doi.org/10.14283/jpad.2024.116
Farag S, Tsang C, Al-Dujaili EAS, Murphy PN. Effect of Polyphenol Supplementation on Memory Functioning in Overweight and Obese Adults: A Systematic Review and Meta-Analysis. Nutrients. 2024 Feb 6;16(4):474. doi: 10.3390/nu16040474. PMID: 38398799; PMCID: PMC10893550.
Godos J, Micek A, Mena P, Del Rio D, Galvano F, Castellano S, Grosso G. Dietary (Poly)phenols and Cognitive Decline: A Systematic Review and Meta-Analysis of Observational Studies. Mol Nutr Food Res. 2024 Jan;68(1):e2300472. doi: 10.1002/mnfr.202300472. Epub 2023 Oct 27. PMID: 37888840.
Holland TM, Agarwal P, Wang Y, Dhana K, Leurgans SE, Shea K, Booth SL, Rajan KB, Schneider JA, Barnes LL. Association of Dietary Intake of Flavonols With Changes in Global Cognition and Several Cognitive Abilities. Neurology. 2023 Feb 14;100(7):e694-e702. doi: 10.1212/WNL.0000000000201541. Epub 2022 Nov 22. PMID: 36414424; PMCID: PMC9969915.
Cheng N, Bell L, Lamport DJ, Williams CM. Dietary Flavonoids and Human Cognition: A Meta-Analysis. Mol Nutr Food Res. 2022 Nov;66(21):e2100976. doi: 10.1002/mnfr.202100976. Epub 2022 Apr 7. PMID: 35333451; PMCID: PMC9787524.
Kaplan A, Zelicha H, Yaskolka Meir A, Rinott E, Tsaban G, Levakov G, Prager O, Salti M, Yovell Y, Ofer J, Huhn S, Beyer F, Witte V, Villringer A, Meiran N, B Emesh T, Kovacs P, von Bergen M, Ceglarek U, Blüher M, Stumvoll M, Hu FB, Stampfer MJ, Friedman A, Shelef I, Avidan G, Shai I. The effect of a high-polyphenol Mediterranean diet (Green-MED) combined with physical activity on age-related brain atrophy: the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT PLUS). Am J Clin Nutr. 2022 May 1;115(5):1270-1281. doi: 10.1093/ajcn/nqac001. PMID: 35021194; PMCID: PMC9071484.
Lamport DJ, Williams CM. Polyphenols and Cognition In Humans: An Overview of Current Evidence from Recent Systematic Reviews and Meta-Analyses. Brain Plast. 2021 Feb 9;6(2):139-153. doi: 10.3233/BPL-200111. PMID: 33782647; PMCID: PMC7990468.
Ahles S, Joris PJ, Plat J. Effects of Berry Anthocyanins on Cognitive Performance, Vascular Function and Cardiometabolic Risk Markers: A Systematic Review of Randomized Placebo-Controlled Intervention Studies in Humans. Int J Mol Sci. 2021 Jun 17;22(12):6482. doi: 10.3390/ijms22126482. PMID: 34204250; PMCID: PMC8234025.
Morton L, Braakhuis AJ. The Effects of Fruit-Derived Polyphenols on Cognition and Lung Function in Healthy Adults: A Systematic Review and Meta-Analysis. Nutrients. 2021 Nov 27;13(12):4273. doi: 10.3390/nu13124273. PMID: 34959825; PMCID: PMC8708719.
Mattioli R, Francioso A, Mosca L, Silva P. Anthocyanins: A Comprehensive Review of Their Chemical Properties and Health Effects on Cardiovascular and Neurodegenerative Diseases. Molecules. 2020 Aug 21;25(17):3809. doi: 10.3390/molecules25173809. PMID: 32825684; PMCID: PMC7504512.
Shishtar E, Rogers GT, Blumberg JB, Au R, Jacques PF. Long-term dietary flavonoid intake and risk of Alzheimer disease and related dementias in the Framingham Offspring Cohort. Am J Clin Nutr. 2020 Aug 1;112(2):343-353. doi: 10.1093/ajcn/nqaa079. PMID: 32320019; PMCID: PMC7398772.doi: 10.3389/fimmu.2023.1024120. PMID: 37033930; PMCID: PMC10073448.
Morris MC, Wang Y, Barnes LL, Bennett DA, Dawson-Hughes B, Booth SL. Nutrients and bioactives in green leafy vegetables and cognitive decline: Prospective study. Neurology. 2018 Jan 16;90(3):e214-e222. doi: 10.1212/WNL.0000000000004815. Epub 2017 Dec 20. PMID: 29263222; PMCID: PMC5772164.
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