Primary Key Points
Tea and Brain Health: Tea consumption has neuroprotective properties that can help prevent cognitive decline and dementia.
Key Tea Components: Tea's main components—EGCG (a powerful antioxidant), caffeine (boosts energy and focus), and L-theanine (promotes relaxation and sharpness)—work together to enhance cognitive function and reduce the risk of neurodegenerative diseases like Alzheimer's and Parkinson's.
Epidemiological Evidence: Studies have shown that regular tea consumption is associated with a lower risk of dementia and other cognitive impairments.
Introduction
Are you one of those who enjoy a daily cup of tea? If so, you’re not alone. Tea is a popular beverage consumed daily in more than 160 countries.
And you’d be happy to know that drinking tea goes beyond a simple daily indulgence. Scientists are examining how tea exerts its effects on mood and cognition. They even concentrated on the neuroprotective benefit of tea and its potential to prevent dementia.
What is Dementia
Dementia symptoms include memory loss and difficulties with thinking, problem-solving, or language. It also involves changes in mood, perception, or behavior.
With the accelerated aging population in the world, neurodegenerative diseases such as Parkinson’s disease and Alzheimer’s disease are increasing over time. The World Alzheimer Report has shown that the number of people with dementia worldwide was 46.8 million in 2015, and it will be 131.5 million in 2050.
It is important to note that dementia is not a natural part of aging. All types of dementia are caused by diseases that affect the brain. And yes, there are risk factors that you can’t control, like genes, but there are still many things you can do to reduce your risk of developing dementia.
One such way is drinking tea daily. But how can tea help? To understand that, we must first look at the main tea components.
Main Tea Components
1. Epigallocatechin-3-gallate (EGCG)
The majority of catechins present in tea are epigallocatechin-3-gallate, which is a type of polyphenol. (1)
Research has found that EGCG increases the production and activity of essential antioxidants such as glutathione peroxidase, superoxide dismutase, and catalase. (2)
EGCG has been shown to protect the brain and prevent cognitive impairment associated with Alzheimer’s.
2. Caffeine
Caffeine can enhance aerobic athletic performance. It can also increase lipolysis, which is the breakdown of stored fat into free fatty acids that can be used for energy. (3) (4)
3. L-Theanine
L-theanine has anti-anxiety effects and can increase mental sharpness. (5) It can cross the blood-brain barrier via the leucine-preferring transport system.
Also, L-theanine improves neurotransmitters in the brain: GABA, dopamine, and serotonin. (6)
In a double-blind, controlled trial, L-theanine improved stress response in 12 undergraduate men. (7)
Combined with caffeine, L-theanine counteracts its adverse effects, increasing focus and reaction time and improving working memory. (8) (9)
Neuroprotective Effects and Mechanisms of Tea Polyphenols
The brain, the most oxygen-consuming organ in the body, is easily damaged by oxidative stress, such as free radicals and redox-active metals (10). Tea polyphenols are natural antioxidants with radical-eliminating capacity.
In addition, EGCG has been reported to scavenge free radicals by directly or indirectly blocking free radical chain reactions, activating intracellular antioxidant enzyme activity, chelating metal ions (11), reducing lipid peroxidation (12), and releasing intracellular calcium (13).
Also, much evidence has indicated that tea polyphenols exert a neuroprotective role in neurodegenerative diseases through their antioxidant properties and the regulation of signaling pathways.
A variety of intracellular signaling pathways, including protein kinase C (PKC), play an essential role in EGCG's neuroprotective effect.
PKC is related to merging different kinds of memories (14), and activated PKC has been shown to prevent the toxic effects of induced amyloid-beta on hippocampal neurons. In other words, the activation of PKC by EGCG may serve as a treatment for the aging brain, such as Alzheimer’s disease. (15) (16)
Epidemiological Evidence
Many population-based studies have shown that drinking tea is related to a lower risk of cognition impairment.
A follow-up study for 5.7 years involving 13,645 Japanese over 65 years old showed that green tea consumption significantly reduced the risk of dementia. (17)
Another study among 278 Parkinson’s disease patients revealed that the onset of Parkinson's was delayed by 7.7 years when tea consumption was more than 3 cups a day. (18)
Another study of people over 55 in Singapore found that those who drank as little as one cup of tea per week performed better at memory and information-processing tasks than non-tea drinkers. (19)
Many meta-analysis studies have also shown that tea intake has neuroprotective effects. For example, data from 26 previous observations, including 52,503 participants, showed that daily tea consumption could significantly lower the risk of cognitive decline, cognitive impairment, and mild cognitive impairment in the elderly. (20)
A study including 34,4895 participants showed that daily consumption of 2 cups of tea decreased Parkinson’s disease risk by 26%. (21)
Conclusion
Many studies have examined tea's medicinal value, testing its effects on everything from stress levels to diabetes.
In addition, tea is easy to make, whether you brew tea leaves or use bagged tea. And you can easily find your favorite flavor and add it to your daily diet.
So, if you’re a tea drinker, you can benefit from these excellent benefits.
FAQ
What is dementia?
Dementia is a group of symptoms, including memory loss and difficulties with thinking and language, often caused by neurodegenerative diseases like Alzheimer's and Parkinson's.
How does tea help with brain health?
Tea contains polyphenols like EGCG, antioxidants that protect brain cells from damage caused by oxidative stress. Caffeine and L-theanine enhance mental clarity and promote relaxation, contributing to brain health.
How much tea should I drink to benefit from its neuroprotective effects?
Research suggests that drinking at least 1-3 cups of tea daily can provide cognitive benefits and reduce the risk of neurodegenerative diseases like Alzheimer's and Parkinson's.
Additional Readings
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References
(1)Epigallocatechin-3-gallate (EGCG): Chemical and biomedical perspectives (nih.gov)
(5)L-theanine, a natural constituent in tea, and its effect on mental state - PubMed (nih.gov)
(7)L-Theanine reduces psychological and physiological stress responses - PubMed (nih.gov)
(18)Smoking and tea consumption delay onset of Parkinson's disease - PubMed (nih.gov)