Green Tea for Memory
Green tea is the one of the best healthful natural remedies to come out of Asian traditional medicine. It is definitely the best tea available. As more people adopt this tea, researchers are unearthing new evidences to support its health claims in traditional medicine. Is memory enhancement one of these proven uses? Read on to find out.
Green tea is native to China and a staple drink in most of Asia. It is made solely from the leaves of Camellia sinensis which have undergone only a little oxidation during processing.
A lot of factors can affect the relative composition of the phytochemicals green tea leaves. For example, the quality of green tea depends on the soil on which it is grown, the climate of the area, when it is harvested and how it is processed.
In recent years, green tea is also becoming popular in the West where black tea has been the traditional tea of choice. This shift is due to the increasing number of studies that are showing the health benefits (and oftentimes, the superiority) of green tea.
The flavonoid content of tea is one example of the phytochemicals that make it a healthful drink. It has been calculated that the flavonoid content of green tea surpasses those of fruits, vegetable juices and wine.
Flavonoids are prized phytochemicals because of their anticarcinogenic and antioxidant properties.
These and other beneficial phytochemicals in green tea have been demonstrated to help reduce the risks of certain cancers and heart disease.
Some of the other healthful phytochemicals in green tea are vitamin C, carotenoids and tocopherols as well as zinc, selenium, chromium and manganese.
Another important group of phytochemicals found in green tea is polyphenols. Of polyphenols, catechins are the most important and of catechins, epigallocatechin gallate is the most abundant.
Besides its ability to reduce the risks of some cancers and heart disease, both animal and human studies have also demonstrated that green tea is useful in the treatment of rheumatoid arthritis, dental cavities, bone loss and kidney stones.
Other benefits of green tea include improving immune function and reducing blood pressure, LDL (“bad” cholesterol) and total cholesterol levels. Green tea (especially if it has high polyphenol content) also increasing thermogenesis and can, therefore, help reduce fat storage and weight gain.
Green tea is also shown to help learning and memory as well as other aspects of cognitive functioning.
Different studies have identified that the active compound in green tea responsible for its neuroprotective properties is epigallocatechin gallate or EGCG. It is known to protect brain cells from dying and restoring damaged neurons.
Epigallocatechin gallate is the most abundant catechins in green tea. Black tea does not contain epigallocatechin gallate because the phytochemical is converted to other compounds during processing.
EGCG is a powerful antioxidant. It is available as an ingredient in many supplements.
The therapeutic uses of EGCG are mainly due to this antioxidant property. It is used to reverse dementia either caused by AIDS or neurodegenerative disease such as Alzheimer’s. EGCG is also used in cancer treatment, to treat chronic fatigue and muscular atrophy.
While it has been long known that the antioxidant property of some of the phytochemicals in green especially EGCG is beneficial for memory, some new studies are showing other benefits for EGCG in the brain.
EGCG as an antioxidant protects the neurons from damage caused by reactive oxygen species and other harmful free radicals. This protection allows nerve cells to continue working and for neuronal transmission to proceed normally.
This effect prevents cognitive decline and is especially beneficial if the damage to brain cells is not permanent or extensive. However, the secondary mechanism by which the EGCG in green improves memory and learning may help explain why green tea can reverse cognitive decline and improve memory even in healthy people.
In a study published in the journal, Molecular Nutrition and Food Research in 2012, Chinese scientists were able to demonstrate that EGCG is able to stimulate neurogenesis in the brain.
Unlike the antioxidant protection provided by EGCG, neurogenesis is a proactive mechanism of action of this green tea phytochemical.
Neurogenesis refers to the generation of new brain cells. It is important because it can help improve brain function. While free radicals kill off brain cells, neurogenesis turn up a new generation of these cells.
When the rate of neurogenesis exceeds the rate at which free radicals damage brain cells, the net result is a maintenance or improvement in cognition.
In this study, the researchers were able to demonstrate that EGCG stimulated neurogenesis in the hippocampus, a prime area of the brain involved in learning and memory. EGCG increased the production of neural progenitor cells which behave like stem cells because they can be turned into any kind of brain cells.
Even though this study involved mice, it is likely that the same effect applies to humans.
This study demonstrates that ECGC (and by extension, green tea) improves memory and other aspects of cognition by promoting neurogenesis and by protecting nerve cells by their antioxidant properties.
In an earlier study published in the journal, Bioscience, Biotechnology and Biochemistry in 2004, researchers demonstrated that the polyphenol extract of green tea improved memory and cognition by inhibiting the enzyme known as acetylcholinesterase.
Acetylcholinesterase is the enzyme that breaks down the neurotransmitter, acetylcholine in the brain.
Given the importance of acetylcholine and the cholinergic pathway to learning and memory, increased acetylcholinesterase activity can reduce the quality and span of memory.
As we age, this effect becomes even more important because acetylcholine production declines with age. To improve cholinergic activity in old age, drugs that inhibit acetylcholinesterase can have profound effects on learning and memory by preventing cognitive decline.
The polyphenols in green tea do inhibit acetylcholinesterase, and therefore, they can prevent short-term memory loss especially in the elderly and those suffering from neurodegenerative diseases such as Alzheimer’s.
If green tea can indeed improve memory it must cause discernible changes in the areas of the brain responsible for cognition. This hypothesis was tested by some researchers who published their findings in the European Journal of Clinical Nutrition.
The neuroimaging method used was MRI (magnetic resonance imaging). This imaging technique was used on human subjects who took a whey-based beverage containing green tea.
The brain imaging result showed that green tea lit up an important area of the cortex. More specifically, the polyphenol content of green tea was linked with increased activation of the dorsolateral prefrontal cortex which is the part of the brain responsible for working memory.
In a 2007 study published in the journal, Biogerontology, researchers investigated the effects of catechins found in green tea in mice bioengineered to quickly develop cognitive decline.
An average dose of 35 mg/kg per day of green tea catechins was fed to these mice through their water supply from their 1st month to 15th month.
The study result showed that the daily consumption of green tea catechins prevented oxidative damage to DNA and memory decline in these mice. These effects meant that the green tea catechins given to these mice delayed cognitive decline.
This study shows that there is a clear benefit to daily consumption of green tea even in humans. The catechins contained in green tea can slow down cognitive decline and even prevent dementia in the elderly.
In a 2006 study published in the Journal of Nutrition, the benefit of long-term consumption of green tea was also confirmed. This study measured the antioxidant benefits of the polyphenols in green tea and how that translates to real-world improvements in memory and learning.
The green tea catechins given to the rats in this study was Polyphenon E which contains different concentrations of various epigallocatechins. The rats were given this green tea extract over a period of 26 weeks.
The results showed that green tea catechins not only reduced the concentrations of reactive oxygen species in the plasma but, more importantly, also in the lower hippocampus.
This later site is responsible for the improvement in spatial cognitive learning in the rats.
This study confirms that the antioxidant protection of green tea affects every organ in the body. In the cardiovascular system, this reduces the risk of heart disease but in the brain, this prevents cognitive decline and improves memory and learning.
In a 2005 study published in The Journal of Neuroscience, scientists fully demonstrated that EGCG can help in the treatment of Alzheimer’s disease.
One of the major cause of Alzheimer’s disease is the deposition of beta amyloid proteins on neurons as plaques.
By giving EGCG derived from green tea to bioengineered mice expressing the precursor proteins for beta amyloid, the researchers were able to demonstrate that this green tea polyphenol is an effective way to reduce the conversion of the precursor protein to the plaques that form in the brain.
EGCG promoted the release of an enzyme known as secretase which then breaks the amyloid precursor protein down.
This study demonstrates the benefit of daily green tea consumption in the treatment of Alzheimer’s disease. Although human studies are still needed, the result obtained with animal models is positive enough to advice dietary green tea consumption for this reason especially since green tea provides other health benefits and is well tolerated.
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