Green Tea Extract – An Overview
Green tea extract may have a nootropic effect on:
- Brain health
- Cognitive function.
Green tea (Camellia sinensis) has been traditionally used in Asia, especially in Japan and China, for thousands of years.
The growing research on green tea’s health benefits has caused a recent surge of interest in the West.
It is clear from recent studies (in addition to thousands of years of use by some cultures) that green tea has many positive effects.
And, the benefits of green tea are not only found in the beverage itself; you can also purchase concentrated extract.
What Does Green Tea Extract Do?
Green tea extract has multiple apparent benefits for the body and brain.
Green Tea For Memory
Several studies associate green tea extract with better working memory, memory formation, and recall. This is especially true for people who are suffering from some form of cognitive impairment.
However, it is clear that even healthy people can experience memory benefits from taking green tea extract.
A 2011 Korean study found that a combination of green tea extract and l-theanine improved memory and selective attention in adults with mild cognitive impairment.
They noted that “brain theta waves, an indicator of cognitive alertness, were increased significantly” after taking the supplements for 16 weeks versus the placebo group.
The patients also performed better on a series of memory and recognition tests.1Park SK, et al. NA combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study J Med Food. 2011
Another study looked at healthy volunteers as they performed working memory tasks under an MRI.
The volunteers were given either green tea extract or a placebo. They noticed that green tea extract significantly increased bilateral activity in the dorsolateral prefrontal cortex.
The researchers claim that this is “a key area that mediates working memory processing in the human brain.”
So, seeing this region light up under the MRI is a good indication of how green tea extract may work on memory. More imaging studies need to be done, but this is a good clue as to this nootropics mechanism of action.2Borgwardt S, et al. Neural effects of green tea extract on dorsolateral prefrontal cortex Eur J Clin Nutr. 2012
Another study looked at green tea extract in both older and younger women. The older cohort saw an increased performance on their reading span, although the results were less evident for the younger cohort.
According to the researchers, “this study provides preliminary evidence that consumption of green tea extract may enhance cognitive performance in older adults and thus provide potential chemopreventive benefits in this group.”3Liu Y, Fly AD, Wang Z, Klaunig JE. The Effects of Green Tea Extract on Working Memory in Healthy Women J Nutr Health Aging. 2018
A 2018 study looked at a combination of omega 3 essential fatty acids, green tea catechins, and ginsenosides over a one month period on cognitively healthy older adults.
This combination “was associated with suggestive changes in cognitive functioning as well as modification of brain activation and brain functional connectivity in cognitively healthy older adults.”
Although there are some other supplements in play, this study does support green teas positive role in memory.4Carmichael OT, et al A Combination of Essential Fatty Acids, Panax Ginseng Extract, and Green Tea Catechins Modifies Brain fMRI Signals in Healthy Older Adults J Nutr Health Aging. 2018
A team of German researchers looked at green tea extract and working memory processing in healthy adult males under MRI.
They found a “beneficial effect of green tea on cognitive functioning,” and suggest that this may be due to “changes in short-term plasticity of parieto-frontal brain connections.”
Communication between the parietal and frontal lobes of the brain is thought to be one of the most important factors in overall cognitive ability and general intelligence.
So, by increasing brain plasticity, green tea extract may provide an overall mental boost to the user.5André Schmidt, et al. Green tea extract enhances parieto-frontal connectivity during working memory processing Psychopharmacology (Berl). 2014
Green Tea For Alzheimer’s
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder caused (at least partially) by β-amyloid plaques in the brain.
There is evidence that green tea extract can fight the symptoms of this neurological disease.
Green tea has the potential to prevent the progression of neurodegenerative pathologies and to promote cognitive performance.
Flavonoids found in green tea extract have been shown to inhibit the development of Alzheimer’s disease.6Williams RJ, Spencer JP. Flavonoids, cognition, and dementia: actions, mechanisms, and potential therapeutic utility for Alzheimer disease Free Radic Biol Med. 2012
Multiple population studies have found a strong link between the amount of green tea consumed and the prevalence of diseases like Alzheimer’s.
More green tea is associated with a lower prevalence of cognitive impairment in humans.
A 2002 study looked at a cross-section of 1003 Japanese citizens aged 70 or older.
They determined their green tea consumption then subjected them to a short mental state exam.
They found significantly lower cognitive impairment in the subjects that consumed green tea, with the individuals who consumed the most green tea seeming the most neuroprotective effects.7Kuriyama S, et al. Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project 1 Am J Clin Nutr. 2006
Another large survey looked at the association between green tea consumption and cognition in 2,501 people aged over 55 years.
Similar to the first study, researchers showed that the intake of green tea was significantly related to a lower prevalence of cognitive impairments.8Ng TP, et al. Tea consumption and cognitive impairment and decline in older Chinese adults Am J Clin Nutr. 2008
Green Tea For Cognitive Enhancement
One brain imaging trial saw that green tea extract may modulate brain activity in the dorsolateral prefrontal cortex, a key area that mediates working memory processing in the human brain.9Borgwardt S, et al. Neural effects of green tea extract on dorsolateral prefrontal cortex Eur J Clin Nutr. 2012
A similar study found that green tea extract could increase parieto-frontal connectivity in the brain.
Parieto-frontal activity refers to how well different brain regions integrate to form intelligent behaviors. This has huge implications for pretty much all cognitive processes.
A team of researchers looked at MRI scans of subjects that took either green tea or a placebo and saw higher levels of activity between brain regions in the green tea group.
They proposed that “the magnitude of green tea induced increase in parieto-frontal connectivity positively correlated with improvement in task performance.”
This promotion of inter-brain communication could be critical to understanding green tea’s nootropic effect.10André Schmidt, et al Green tea extract enhances parieto-frontal connectivity during working memory processing Psychopharmacology (Berl). 2014
A combination of green tea extract and l-theanine improved memory and mental function in adults with mild cognitive impairment.
Brain scans showed theta waves, an indicator of cognitive alertness was higher in those that took the green tea extract/l-theanine combo.
Animal and in vitro studies have shown that EGCG can pass through the blood-brain barrier to act directly on the brain, and that it might improve the health of blood vessels and boost the supply of nitric oxide that together could benefit cognitive function.11Park SK, et al. A combination of green tea extract and l-theanine improves memory and attention in subjects with mild cognitive impairment: a double-blind placebo-controlled study J Med Food. 2011
Another study that singled out on one of green tea’s polyphenols supports this. Epigallocatechin (EGCG), which is a major constituent of green tea, has been shown to contribute to an increase in brain activity across all bandwidths.
Alpha waves; theta waves, which are associated with quiet wakefulness; and beta waves, which increase with focus and attention.
According to researchers, “this pattern of results suggests that participants in the EGCG condition may have been in a more relaxed and attentive state after consuming EGCG.”12Scholey A, et al Acute neurocognitive effects of epigallocatechin gallate (EGCG) Appetite. 2012
A 2014 meta-analysis on ECGC and l-theanine (both found in green tea) found a pronounced effect on alertness, calmness, and contentedness across multiple studies.13Camfield DA, Stough C, Farrimond J, Scholey AB. Acute effects of tea constituents L-theanine, caffeine, and epigallocatechin gallate on cognitive function and mood: a systematic review and meta-analysis Nutr Rev. 2014
Green Tea For Depression
According to research, drinking at least half a cup of green tea a day could lower the risk of developing depression and dementia. There are multiple population studies that seem to bear this out.
One longitudinal study investigated green tea consumption with self-reported lifetime depression in the Korean population.
They found that the green tea drinkers had a 32% lower prevalence of depression. This is a significant result.14Jiwon Kim, Jihye Kim. Green Tea, Coffee, and Caffeine Consumption Are Inversely Associated with Self-Report Lifetime Depression in the Korean Population Nutrients 2018
High consumption of green tea significantly lowered the prevalence of depressive symptoms among a survey of 1058 elderly Japanese.15Kaijun Niu, et al. Green tea consumption is associated with depressive symptoms in the elderly The American Journal of Clinical Nutrition, 2009
How Green Tea Extract Works In The Brain
Green tea extract condenses all of the health benefits of drinking the tea itself.
What Makes Green Tea So Healthy?
Green tea is processed in a manner to prevent the enzymatic oxidation of catechins. What does that mean?
Well, catechins are a type of phenolic compound you can find in tea, cocoa, and berries. They are potent antioxidants with many healthy anti-inflammatory properties.
However, when the catechins in tea become oxidized (through exposure to the air), they degrade, the tea loses these benefits.
So, green tea is quickly heated and dried after it is picked to preserve the catechins before they lose their potency.
Catechins are not the only type of phenolic chemical in green tea. It also contains a wide array of other polyphenols that have proven health benefits.
Green tea beverages contain different polyphenol constituents due to the changes that occur during manufacturing.
Green tea also contains the nootropic l-theanine that can improve cognitive function.
This amino acid is one of the most popular nootropics out there and can induce a state of calm, relaxed focus, especially when combined with caffeine (which, conveniently enough, is also present in green tea.)
In short, these various compounds work synergistically to make green tea one of the healthiest drinks, if not THE healthiest drink, on Earth.
And, fortunately, green tea extracts can capture those benefits in a capsule for those who don’t have the time or interest in brewing the actual leaves.
How Much Green Tea Extract Should I Take?
This nootropic is extremely safe and non-toxic.
Most people will probably see the maximum benefit at around 250 mg per day, which is the equivalent of about 2 cups of brewed green tea.
This is about the amount that most studies used, and it seems to be pretty effective.
Green Tea Extract Potential Side Effects
There are no known side effects for this nootropic.
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