Brain-Protective Effects of Green Tea
July 2021
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
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.
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WHAT YOU NEED TO KNOW |
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Green Tea |
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Green tea polyphenols have been associated with many diverse health benefits.
Functional Disability
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
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.
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HOW GREEN TEA HELPS THE BRAIN |
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Green tea has been found to offer multiple beneficial effects for health and metabolism that support whole-brain health. Boosting Neurogenesis and Neuroplasticity
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
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 of head trauma. Green tea reduces both the severity of injury and the functional deficits that results.29,42,43 |
When we’re young, our brains operate at peak performance.
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.
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Mega Green Tea Extract (Lightly Caffeinated), 100 vege caps
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