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The Health Benefits of Green Tea

Updated: Apr 29

Part:1

JAMES MESCHINO, DC, MS, ND


With so much hype about many different health foods, it’s hard to separate fact from fiction, but green tea is the real deal. Green tea (Camellia sinensis) was discovered in China in 3000 BC or earlier. It was brought to Japan from China by Buddhist priests over a thousand years ago. Black tea is also derived from the same plant as green tea, but when harvested black tea is processed differently from green tea in that it is oxidized, which changes its composition to a significant degree.


A big difference between green tea and black tea is that green tea contains much more polyphenols or catechin constituents, including the highly medicinal EGCG (epigallocatechin-3-gallate). EGCG has been investigated for its anti-cancer, anti-obesity, anti-atherosclerotic (plaque build-up in the arteries), anti-diabetic, anti-bacterial, anti-viral, and anti-dental caries effects. Unlike many other natural substances and supplements, many human clinical trials using green tea extract (high in EGCG) have been carried out and, for the most part, they show impressive and consistent positive health effects, especially with respect to anti-cancer properties, enhancing weight loss, improving diabetic management and possibly helping to ward off age-related memory loss, Alzheimer’s disease and possibly other neurodegenerative diseases.


In a series of upcoming Healthy Lifestyle Boosters on green tea, I will highlight some of the most impressive studies where green tea extract has been used to prevent or better manage important health conditions or health risk factors.


As a starting point, green tea EGCG constituents are linked to reduced risk of memory loss with aging (age-related cognitive impairment). Various experimental studies show that EGCG can do a number of remarkable things to prevent memory loss problems in aging, and in 2019 a landmark study showed that EGCG supplementation given to adults (ages 18-55 years) who have Fragile X Syndrome, showed significantly improved cognition, including memory and improved functional competence in everyday life.


Fragile X Syndrome is a genetic disorder whereby the brain cannot make a key protein (FMR1 gene) needed for normal brain development, and thus, these individuals exhibit major developmental delays (not sitting or walking at predictable times in development), learning disabilities, social and behavioral problems (not making eye contact, attention problems, anxiety, hand flapping, acting and speaking without thinking and being very active). EGCG supplementation at 5-7 mg per kg of body weight per day in these subjects resulted in significant improvement in memory and daily function after just 3 months (Reference 2). I’ll explain what we know about EGCG’s impact on the brain in upcoming editions.



References

  1. Main Reference: Suzuki Y et al. Health-promoting effects of green tea. Proc Jpn Acad Ser B Phys Biol Sci. 2012;88(3):88-101 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3365247/

  2. de la Torre et al. A phase 1, randomized double-blind, placebo-controlled trial to evaluate safety and efficacy of epigallocatechin-3-gallate and cognitive training in adults with Fragile X syndrome. Clinical Nutrition. 2020; 39(2):P378-387 https://www.clinicalnutritionjournal.com/article/S0261-5614(19)30082-2/abstract



Green Tea Extract Inhibits a Key Signaling Mechanism in Cancer (c-Met receptor)


Part: 2

JAMES MESCHINO, DC, MS, ND


Another way that green tea catechins (especially EGCG) have been shown to inhibit prostate cancer promotion and progression is by inhibiting the stimulation of c-Met receptors on prostate cancer cells (and colon cancer cells).


In many cases of prostate cancer, as normal cells become transformed into cancer cells, they over-express receptors (little antennas) on the surface of the cell called c-Met receptors.


When stimulated by a protein called the HGF (hepatocyte growth factor) these receptors trigger the cell to divide quickly, invade adjacent tissue and metastasize, creating a dangerous and life-threatening version of the disease.


Experimental studies show that green tea extract, along with two other natural agents (resveratrol and curcumin) inhibit HGF from stimulating c-Met receptors, helping to reduce the invasiveness and aggressiveness of these cancer cells.


This mechanism may be one more way in which the regular consumption of green tea and green tea extract (EGCG) may help to ward off prostate and other cancers. As we await large human clinical trials to confirm these findings, it is encouraging to see that many observational studies show that green tea drinkers around the world have decreased incidence of prostate, breast and stomach cancers.



References

  1. Cancer Research Journal: https://cancerres.aacrjournals.org/content/64/7_Supplement/425.1

  2. National Cancer Control Policy -Australia: https://wiki.cancer.org.au/policy/Position_statement_-_Tea_and_cancer_prevention




Green Tea Catechins Inhibit a Key Pathway in Cancer Development and Progression: (The TK Pathway)


Part: 3

JAMES MESCHINO, DC, MS, ND


Another way that green tea catechins may help to prevent certain cancers is by inhibiting a key signaling pathway within emerging cancer cells, known as the TK Pathway (tyrosine kinase).


TK is a receptor found in the outer skin of cells. When a normal cell morphs into a cancer cell, the TK receptors very often become dysfunctional and overactive. This overactivity sends signals to other switches within the cell (signal transduction) that turn on genes instructing the cell to divide out of control (that’s what cancer really is – uncontrolled growth of dysfunctional cells), and can trigger other signaling mechanisms that stimulate these tumor cells to metastasize to other tissues and organs and start new tumor colonies.


Experimental and animal studies show that green tea catechins block the dysfunctional behavior of TK (tyrosine kinase) in many different types of cancer cells and cancer models, making them less aggressive, slowing their cell division rate and metastatic potential.


This may be another reason to consider drinking 3-5 cups of green tea each day.



References

  1. Green Tea Catechins Inhibit Tyrosine Kinase (TK): Various Mechanisms of Cancer Prevention from Green Tea Catechins: https://www.mdpi.com/1420-3049/21/12/1679/htm

  2. Tyrosine Kinase in Cancer: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1074718/#:~:text=Tyrosine%20kinases%20are%20important%20mediators,in%20the%20pathophysiology%20of%20cancer


Green Tea Intake Associated with Reduced Risk of Dementia, Alzheimer’s disease, and Mild Cognitive Impairment


Part: 4

JAMES MESCHINO, DC, MS, ND


The authors of a study published in 2019 in the journal Nutrients reviewed all available studies looking at green tea intake and memory, The researchers concluded, " These results seem to support the hypothesis that green tea intake might reduce the risk for dementia, Alzheimer’s disease, mild cognitive impairment, or cognitive impairment. "


Experimental studies show that green tea catechins (i.e., EGCG) protect brain cells from undergoing degeneration and death during the aging process from insults such as free radical attack, the inflammatory process and the build-up of beta-amyloid plaque – a hallmark feature of Alzheimer’s disease. These experimental studies show that green tea catechins act as antioxidants in the brain, inhibit brain inflammation, block steps in brain cell death and inhibit the synthesis of beta-amyloid plaque.


Protecting your brain cells and supporting memory function are other reasons to consider drinking 3-5 cups of green tea each day.



References


  1. Kakutani S et al. Green tea intake and risks of dementia, Alzheimer’s disease, mild cognitive impairment, and cognitive impairment: A systematic review. Nutrients 2019;11(5):1165 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6567241/


Green Tea Catechins Help You Burn Fat at Rest (Thermogenesis)


Part: 5

JAMES MESCHINO, DC, MS, ND


An increasing body of evidence shows that the polyphenol known as EGCG found in green tea and green tea extract turns on the body’s brown fat machinery.


Brown fat is the type of fat we have in our body that burns excess calories we consume and gives them off to the environment as heat. This is known as thermogenesis.

Whereas white fat stores excess calories as fat, brown fat helps to burn off excess calories and releases it as heat to the environment.


The result is that green tea and green tea extract have shown promise in helping to prevent and reverse overweight problems.


This is one more reason to consider drinking 3-5 cups of green tea per day, and/or ingesting a supplement each day that provides 300-600 mg of green tea extract with a high EGCG content (epigallocatechin-3 gallate).


References


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5475335/