Life Extension Magazine®
Woman drinking green tea for boosting brain health by catechins

Brain-Protective Effects of Green Tea

Green tea polyphenols promote the formation of new brain cells and the ability of brain cells to create neural connections. In people who regularly drank green tea, cognitive disorders were found to be 35% lower.

Scientifically reviewed by: Julia Dosik, MPH in Global Health, MS in Medical Health, on February 2021. Written By Sheldon Cannon.

Scientists are finding that compounds found in green tea can bolster and protect brain health.1-4

One meta-analysis found that the rate of cognitive disorders was 35% lower in people who regularly drank tea.5

Parkinson’s disease risk was reduced by 26% for every two cups per day of tea consumed in another study.6

The healthful compounds found in green tea work in several different ways to boost brain function and guard against cognitive decline.

For those who do not consume enough green tea, standardized extracts provide the beneficial polyphenols called catechins.

Green Tea Medicine: Catechins

The tea plant, Camellia sinensis, is packed with the health-promoting compounds known as catechins.

One of the most abundant and widely studied catechins in green tea is epigallocatechin gallate (EGCG).

Studies of whole tea consumption, extracts of green tea, and individual isolated catechins, have all demonstrated health benefits.7-13

Scientists have identified scores of mechanisms by which green tea wards off disease and the ravages of aging.

The widespread consumption of green tea has led to large observational studies that evaluate its association with risk for various disorders, including age-related cognitive decline.

Improving Brain Performance and Mood

Chemical structure of epigallocatechin gallate

Many of these effects of green tea help maintain strong mental function well into the future. But it also has immediate effects that improve brain function now.

Researchers used memory tasks and an advanced imaging technology called functional MRI to evaluate cognitive functions in healthy volunteers.14 They found that people who were given a green tea extract performed better on memory tasks. They also observed enhanced connectivity between areas in the brain involved in the tasks.

This means they were able to demonstrate physiological changes in the brain that correlated with improved mental function.

Another study, using an electroencephalogram to monitor brain activity, saw an overall increase in brain wave activity after consuming an EGCG (green tea extract) supplement.15

Cognitive enhancement isn’t the only mental function impacted by green tea. In studies in healthy adults, green tea also reduced psychological stress, including feelings of anxiety and depression, and led to a feeling of calmness.15,16

Cognitive Impairment, Alzheimer’s, & Dementia

Studies in humans have demonstrated a clear association between tea consumption and a lower occurrence of cognitive disorders, including everything from mild cognitive impairment to Alzheimer’s.5, 17-20

One of the largest studies, a pooled analysis of 52,503 participants in countries around the world, found that tea significantly reduced the rate of multiple kinds of cognitive disorders by 35%.5

Another large meta-analysis evaluated the risk of cognitive disorders in 48,435 individuals.19 Overall, higher tea intake correlated with a significant reduction in cognitive disorders.

However, when researchers further analyzed these results, they found that green tea consumption was more reliably associated with the cognitive benefit than oolong or black tea.

The rate of cognitive disorders in habitual drinkers of green tea was 36% lower than in non-habitual drinkers. Scientists also found a dose-response relationship: The more green tea consumed, the greater the protection from cognitive dysfunction. In practical terms, those who drank 16 ounces of green tea per day derived nearly six times more protection from development of cognitive disorders than those who drank 3.5 ounces.

Other studies have examined tests of cognitive function, rather than diagnoses of cognitive disease.17,18

In older adults, green tea was associated with superior performance on these tests. Green tea drinkers scored better for overall cognition, memory function, executive function, and the speed of information processing. And once again, more tea intake was linked to higher scores.

Parkinson’s Disease

Parkinson’s disease is a neurodegenerative disorder that mostly affects nerve cells in the brain that produce the neurotransmitter dopamine.

It’s marked by a progressive loss of motor function, creating difficulties including tremors, slowed movement, and difficulty initiating movements. In more advanced cases, cognitive loss occurs as well, leading to slowed thinking and dementia.

Case-control studies in non-western populations demonstrate a strong protective effect of tea against the development of Parkinson’s disease.21-23 Up to a 41% lower rate of Parkinson’s was found when comparing those who routinely consume the largest amounts of tea with those who rarely drink tea.

A large meta-analysis included data from a whopping 344,895 individuals all over the world.6 As was observed in the studies of cognitive disorders, researchers noted that the amount of green tea intake correlated with the degree of protection from Parkinson’s disease. In fact, they found that risk of Parkinson’s was reduced by 26% for every two cups per day consumed. This effect was more pronounced in European and Asian populations.

What you need to know

Green Tea

Tea plant being picked for green tea
  • Green tea polyphenols have been associated with many diverse health benefits.
  • In the brain, green tea offers neuroprotective effects and shields the brain from age-related decline by boosting the creation of new brain cells and neural connections.
  • Green tea also reduces the risk for neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease.
  • Many large, human studies have demonstrated that green tea intake is significantly associated with reduced risk for age-related cognitive decline and dementia.

Functional Disability

Brain neurons being boosted through neurogenesis

One large, prospective study evaluated the impact that green tea can have on functional disability, regardless of the underlying cause.24 Almost 14,000 Japanese individuals over the age of 64 were followed over time. Researchers found a significant protective effect of greater green tea intake, reducing the risk for disability and the need for support for daily activities.

Yet again, the more tea a person consumed, the greater the protection observed. Those who drank five or more cups per day were 33% less likely to have a significant functional impairment than those who consumed less than a cup per day. It’s difficult to consume this much green tea but extracts typically contain the amount of polyphenols equivalent to many cups.

Summary

Cup of green tea being poured

Green tea and its extracts are widely recognized for their numerous health benefits.

In the nervous system, green tea provides many protective effects, including:

  • Boosting neurogenesis (the creation of new brain cells) and neuroplasticity (the ability of the brain to adapt) into old age,13, 25-33
  • Shielding from the progressive damage that leads to neurodegenerative disorders,2, 34-38 and
  • Offering neuroprotection against injuries such as stroke and head trauma.29, 39-42

In the short term, green tea also boosts cognitive function, supporting attention, focus, improvement in mood, and enhanced memory.

Large studies in humans have demonstrated that green tea and its extracts are capable of guarding against age-related brain dysfunction and risk for dementia.

While drinking five or more cups of tea per day is difficult, green tea extracts that provide high quantities of polyphenols (catechins) are available in capsule form.

Green tea extracts are available in decaffeinated forms, for those sensitive to caffeine.

For those interested in the biological mechanisms that enable green tea to confer brain protection, turn to the next two pages.

If you have any questions on the scientific content of this article, please call a Life Extension® Wellness Specialist at 1-866-864-3027.

References

Close up of a tea leaf
  1. Mancini E, Beglinger C, Drewe J, et al. Green tea effects on cognition, mood and human brain function: A systematic review.Phytomedicine. 2017 Oct 15;34:26-37.
  2. Pervin M, Unno K, Ohishi T, et al. Beneficial Effects of Green Tea Catechins on Neurodegenerative Diseases. Molecules. 2018 May 29;23(6).
  3. Polito CA, Cai ZY, Shi YL, et al. Association of Tea Consumption with Risk of Alzheimer’s Disease and Anti-Beta-Amyloid Effects of Tea. Nutrients. 2018 May 22;10(5).
  4. Sangiovanni E, Brivio P, Dell’Agli M, et al. Botanicals as Modulators of Neuroplasticity: Focus on BDNF. Neural Plast. 2017;2017:5965371.
  5. Ma QP, Huang C, Cui QY, et al. Meta-Analysis of the Association between Tea Intake and the Risk of Cognitive Disorders. PLoS One. 2016;11(11):e0165861.
  6. Qi H, Li S. Dose-response meta-analysis on coffee, tea and caffeine consumption with risk of Parkinson’s disease. Geriatr Gerontol Int. 2014 Apr;14(2):430-9.
  7. Carnevale R, Loffredo L, Nocella C, et al. Epicatechin and catechin modulate endothelial activation induced by platelets of patients with peripheral artery disease. Oxid Med Cell Longev. 2014;2014:691015.
  8. Kurbitz C, Heise D, Redmer T, et al. Epicatechin gallate and catechin gallate are superior to epigallocatechin gallate in growth suppression and anti-inflammatory activities in pancreatic tumor cells. Cancer Sci. 2011 Apr;102(4):728-34.
  9. Noll C, Lameth J, Paul JL, et al. Effect of catechin/epicatechin dietary intake on endothelial dysfunction biomarkers and proinflammatory cytokines in aorta of hyperhomocysteinemic mice. Eur J Nutr. 2013 Apr;52(3):1243-50.
  10. Stadlbauer S, Steinborn C, Klemd A, et al. Impact of Green Tea Catechin ECG and Its Synthesized Fluorinated Analogue on Prostate Cancer Cells and Stimulated Immunocompetent Cells. Planta Med. 2018 Jul;84(11):813-9.
  11. Stringer TP, Guerrieri D, Vivar C, et al. Plant-derived flavanol (-)epicatechin mitigates anxiety in association with elevated hippocampal monoamine and BDNF levels, but does not influence pattern separation in mice. Transl Psychiatry. 2015 Jan 6;5:e493.
  12. Van Amelsvoort JM, Van Hof KH, Mathot JN, et al. Plasma concentrations of individual tea catechins after a single oral dose in humans. Xenobiotica. 2001 Dec;31(12):891-901.
  13. Zhang Z, Wu H, Huang H. Epicatechin Plus Treadmill Exercise are Neuroprotective Against Moderate-stage Amyloid Precursor Protein/Presenilin 1 Mice. Pharmacogn Mag. 2016 May;12(Suppl 2):S139-46.
  14. Schmidt A, Hammann F, Wolnerhanssen B, et al. Green tea extract enhances parieto-frontal connectivity during working memory processing. Psychopharmacology (Berl). 2014 Oct;231(19):3879-88.
  15. Scholey A, Downey LA, Ciorciari J, et al. Acute neurocognitive effects of epigallocatechin gallate (EGCG). Appetite. 2012 Apr;58(2):767-70.
  16. Hozawa A, Kuriyama S, Nakaya N, et al. Green tea consumption is associated with lower psychological distress in a general population: the Ohsaki Cohort 2006 Study. Am J Clin Nutr. 2009 Nov;90(5):1390-6.
  17. Feng L, Gwee X, Kua EH, et al. Cognitive function and tea consumption in community dwelling older Chinese in Singapore. J Nutr Health Aging. 2010 Jun;14(6):433-8.
  18. Kuriyama S, Hozawa A, Ohmori K, et al. Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project 1. Am J Clin Nutr. 2006 Feb;83(2):355-61.
  19. Liu X, Du X, Han G, et al. Association between tea consumption and risk of cognitive disorders: A dose-response meta-analysis of observational studies. Oncotarget. 2017 Jun 27;8(26):43306-21.
  20. Yang L, Jin X, Yan J, et al. Prevalence of dementia, cognitive status and associated risk factors among elderly of Zhejiang province, China in 2014. Age Ageing. 2016 Sep;45(5):708-12.
  21. Barranco Quintana JL, Allam MF, Del Castillo AS, et al. Parkinson’s disease and tea: a quantitative review. J Am Coll Nutr. 2009 Feb;28(1):1-6.
  22. Hosseini Tabatabaei N, Babakhani B, Hosseini Tabatabaei A, et al. Non-genetic factors associated with the risk of Parkinson’s disease in Iranian patients. Funct Neurol. 2013 Apr-May;28(2):107-13.
  23. Tanaka K, Miyake Y, Fukushima W, et al. Intake of Japanese and Chinese teas reduces risk of Parkinson’s disease. Parkinsonism Relat Disord. 2011 Jul;17(6):446-50.
  24. Tomata Y, Kakizaki M, Nakaya N, et al. Green tea consumption and the risk of incident functional disability in elderly Japanese: the Ohsaki Cohort 2006 Study. Am J Clin Nutr. 2012 Mar;95(3):732-9.
  25. Ortiz-Lopez L, Marquez-Valadez B, Gomez-Sanchez A, et al. Green tea compound epigallo-catechin-3-gallate (EGCG) increases neuronal survival in adult hippocampal neurogenesis in vivo and in vitro. Neuroscience. 2016 May 13;322:208-20.
  26. Unno K, Pervin M, Nakagawa A, et al. Blood-Brain Barrier Permeability of Green Tea Catechin Metabolites and their Neuritogenic Activity in Human Neuroblastoma SH-SY5Y Cells. Mol Nutr Food Res. 2017 Dec;61(12).
  27. Zhang JC, Xu H, Yuan Y, et al. Delayed Treatment with Green Tea Polyphenol EGCG Promotes Neurogenesis After Ischemic Stroke in Adult Mice. Mol Neurobiol. 2017 Jul;54(5):3652-64.
  28. Wang Y, Li M, Xu X, et al. Green tea epigallocatechin-3-gallate (EGCG) promotes neural progenitor cell proliferation and sonic hedgehog pathway activation during adult hippocampal neurogenesis. Mol Nutr Food Res. 2012 Aug;56(8):1292-303.
  29. Itoh T, Imano M, Nishida S, et al. (-)-Epigallocatechin-3-gallate increases the number of neural stem cells around the damaged area after rat traumatic brain injury. J Neural Transm (Vienna). 2012 Aug;119(8):877-90.
  30. Erickson KI, Prakash RS, Voss MW, et al. Brain-derived neurotrophic factor is associated with age-related decline in hippocampal volume. J Neurosci. 2010 Apr 14;30(15):5368-75.
  31. Assuncao M, Santos-Marques MJ, Carvalho F, et al. Green tea averts age-dependent decline of hippocampal signaling systems related to antioxidant defenses and survival. Free Radic Biol Med. 2010 Mar 15;48(6):831-8.
  32. Li Q, Zhao HF, Zhang ZF, et al. Long-term administration of green tea catechins prevents age-related spatial learning and memory decline in C57BL/6 J mice by regulating hippocampal cyclic amp-response element binding protein signaling cascade. Neuroscience. 2009 Apr 10;159(4):1208-15.
  33. Li Q, Zhao HF, Zhang ZF, et al. Long-term green tea catechin administration prevents spatial learning and memory impairment in senescence-accelerated mouse prone-8 mice by decreasing Abeta1-42 oligomers and upregulating synaptic plasticity-related proteins in the hippocampus. Neuroscience. 2009 Oct 20;163(3):741-9.
  34. He M, Liu MY, Wang S, et al. [Research on EGCG improving the degenerative changes of the brain in AD model mice induced with chemical drugs]. Zhong Yao Cai. 2012 Oct;35(10):1641-4.
  35. Rezai-Zadeh K, Arendash GW, Hou H, et al. Green tea epigallocatechin-3-gallate (EGCG) reduces beta-amyloid mediated cognitive impairment and modulates tau pathology in Alzheimer transgenic mice. Brain Res. 2008 Jun 12;1214:177-87.
  36. Walker JM, Klakotskaia D, Ajit D, et al. Beneficial effects of dietary EGCG and voluntary exercise on behavior in an Alzheimer’s disease mouse model. J Alzheimers Dis. 2015;44(2):561-72.
  37. Venigalla M, Sonego S, Gyengesi E, et al. Novel promising therapeutics against chronic neuroinflammation and neurodegeneration in Alzheimer’s disease. Neurochem Int. 2016 May;95:63-74.
  38. Caruana M, Vassallo N. Tea Polyphenols in Parkinson’s Disease. Adv Exp Med Biol. 2015;863:117-37.
  39. Babu PV, Liu D. Green tea catechins and cardiovascular health: an update. Curr Med Chem. 2008;15(18):1840-50.
  40. Pang J, Zhang Z, Zheng TZ, et al. Green tea consumption and risk of cardiovascular and ischemic related diseases: A meta-analysis. Int J Cardiol. 2016 Jan 1;202:967-74.
  41. Martins A, Schimidt HL, Garcia A, et al. Supplementation with different teas from Camellia sinensis prevents memory deficits and hippocampus oxidative stress in ischemia-reperfusion. Neurochem Int. 2017 Sep;108:287-95.
  42. Itoh T, Imano M, Nishida S, et al. (-)-Epigallocatechin-3-gallate protects against neuronal cell death and improves cerebral function after traumatic brain injury in rats. Neuromolecular Med. 2011 Dec;13(4):300-9.
  43. Itoh T, Tabuchi M, Mizuguchi N, et al. Neuroprotective effect of (-)-epigallocatechin-3-gallate in rats when administered pre- or post-traumatic brain injury. J Neural Transm (Vienna). 2013 May;120(5):767-83.

How Green Tea Helps the Brain

Green tea has been found to offer multiple beneficial effects for health and metabolism that support whole-brain health.

Boosting Neurogenesis and Neuroplasticity

Bowl of tea leaves being dried out

When we’re young, our brains operate at peak performance.

Neurogenesis, the growth of new brain cells, occurs in the greatest amount during the embryonic stage and continues throughout adulthood. But it wanes with advancing age.

Neuroplasticity, the brain’s ability to adapt and form new neural connections, is critical to learning and maintaining memory and other cognitive functions. It also decreases as we grow older.

Green tea can support both neurogenesis and neuroplasticity.

In animal models and in cell cultures, it’s been shown to stimulate neurogenesis.25-27 In studies like these, EGCG supported new brain cell growth and survival in the hippocampus, a part of the brain critical for the formation of new memories.25,28 In an animal study, it also aided stem cell growth in the brain after a traumatic injury.29

One of the most important mediators of neuroplasticity is a growth factor called brain-derived neurotrophic factor (BDNF). Its levels tend to diminish in old age,30 impairing the ability of the brain to adapt and resist injury.

Green tea has the ability to stimulate production of BDNF to help maintain optimal brain function.

In one study, the drop in BDNF levels in aging rat brains was prevented by supplementing their diet with green tea.31 And in older mice, green tea supplementation prevented the decline in BDNF levels and alleviated learning and memory deficits associated with aging.13,32,33

Protection from Age-Related Damage

Screen display of brain scans

Cognitive disorders are a terrifying scourge of old age. The two most common are mild cognitive decline and Alzheimer’s disease, the most prevalent type of dementia.

The pathology in the brain associated with these disorders includes the deposition of abnormal proteins that accumulate to toxic levels. These proteins, including beta-amyloid and hyperphosphorylated tau, create the plaques and tangles that cause cognitive function to slow dramatically in Alzheimer’s patients.

They also incite neuroinflammation, leading to further injury and cognitive decline.

Green tea protects against these age-related threats in a number of ways.

In several animal studies, green tea was found to significantly reduce the build-up of both these toxic proteins, and even to aid in clearing them from brain tissue.34-36 Reduction of amyloid and tau deposits in these studies protected cognition, preventing age-related memory and learning deficits.

Green tea also has powerful anti-inflammatory effects in the nervous system, acting to reduce the harmful neuroinflammation associated with these diseases.37

Parkinson’s disease has been found to respond to supplementation with green tea as well.2 The buildup of alpha-synuclein and resulting neuroinflammation and neurotoxicity associated with this disease is also reduced by green tea.38

Guarding Against Strokes and Injury

Cognitive disorders aren’t the only risks to brain function in later life. Damage to the brain is also common from strokes and head trauma.

Strokes occur most often as a result of blood vessel disease, which can cause either a blockage of blood flow to the brain or bleeding into the brain. These typically occur suddenly and without warning.

Green tea intake can reduce the risk of brain damage from strokes in multiple ways. For one, green tea’s cardiovascular health benefits help prevent blood vessel disease in the first place. This lowers the risk, not only for stroke, but also for coronary artery heart disease and other conditions.39,40

Green tea can also provide a neuroprotective effect, reducing the impact if an injury does occur. This was demonstrated in a recent study in rats that had suffered a stroke, which found that green tea reduced the severity of injury.41 The degree of tissue necrosis (death), oxidative stress, and cognitive deficits were all lowered by tea, and the neuroprotection was greater with green tea than other types of tea.

Neuroprotection of this type is also observed in animal models ofhead trauma. Green tea reduces both the severity of injury and the functional deficits that result.29,42,43