The Health Secrets of Green Tea - EGCG

Many of us have heard or read about the benefits of consuming green tea and how it can improve our health. Epigallocatechin gallate (EGCG) is the ester of epigallocatechin and gallic acid. EGCG is the primary catechin (fifty percent of the total catechin in green tea) found in green tea. Catechins are natural phenols produced by plants and are considered antioxidants. Catechins are absorbed in our jejunum (part of the small intestine) and are metabolized by our microbiome, liver glucuronidation, sulphation, and O-methylation catalyzed by the COMT [1] (https://selfhacked.com/blog/worrier-warrior-explaining-rs4680comt-v158m-gene/) (catechol-O-methyltransferase) enzyme. EGCG and L-theanine are both found within green tea, which might be why its consumption in moderation might improve your health. EGCG has a half-life of about three hours and thirty minutes and should be taken on an empty stomach.[2] [3] [4]

What are some health benefits of supplementing with epigallocatechin gallate? EGCG has been shown to help improve memory and cognition when combined with L-theanine in people with mild cognitive impairment through increasing theta waves during supplementation of the specific extract LGNC-07. Although EGCG promotes high concentration, it also provides calmness. “EGCG administration was associated with a significant overall increase in alpha, beta and theta activity, also reflected in overall EEG activity, more dominant in midline frontal and central regions, specifically in the frontal gyrus and medial frontal gyrus. In comparison to placebo the EGCG treatment also increased self-rated calmness and reduced self-rated stress. This pattern of results suggests that participants in the EGCG condition may have been in a more relaxed and attentive state after consuming EGCG.”[5] [6]

Epigallocatechin gallate also contains noted antibacterial properties and has been found effective against Gram-negative Proteobacteria like H. pylori. EGCG may also help prevent cancer cells from metastasizing or proliferating, but human clinical trials must be performed to prove efficacy. “Many tested tea polyphenols exert dose-dependent antiproliferative effects, and EGCG showed the most potent activities. Cell cycle arrest and apoptosis induction may play an important role in EGCG-induced cancer cell death.” EGCG may also help improve insulin sensitivity, weight loss, and hyperglycemia in people with type two diabetes. EGCG inhibits the production of the histamine-producing enzyme histidine decarboxylase (catalyzes the conversion of the amino acid histidine into histamine), so it may be a good supplement for people suffering from histamine intolerance and/or mast cell activation disorder. Finally, EGCG can help relieve Th1 (https://selfhacked.com/blog/supplements-foods-exercise-right-type-th1-vs-th2-dominance/)[7] and Th17 (https://selfhacked.com/blog/th17/)[8] dominance and can help reduce an overactive immune system in people suffering from those conditions. “We further demonstrated that EGCG inhibited Th1 and Th17 differentiation by downregulating their corresponding transcription factors (STAT1 and T-bet for Th1, and STAT3 and RORγt for Th17). These effects provide further explanation for previous findings that administration of EGCG by gavage to experimental autoimmune encephalomyelitis (EAE) mice, an animal model for human multiple sclerosis (MS), reduced the clinical symptoms, brain pathology, and proliferation and TNF-α production of encephalitogenic T cells. This protective effect of EGCG is associated with the suppressed proliferation of autoreactive T cells, reduced production of pro-inflammatory cytokines, decreased Th1 and Th17, and increased Treg populations in lymphoid tissues and central nervous system.”[9] [10] [11] [12] [13] [14] [15] [16]

What can epigallocatechin gallate do to help improve our mitochondrial health? EGCG has been shown when supplemented in rats to protect their brain mitochondria from cadmium toxicity (however, there is still a decrease in mitochondria glutathione levels). EGCG can chelate cadmium out of our brain and help eliminate it from our body, which might explain why it prevents cadmium neural and mitochondrial impairment. EGCG, when supplemented to mice, also reduces reactive oxidative species production, and increases adenosine triphosphate levels within their brain mitochondria, increasing their mitochondrial neurological function. EGCG supplementation in moderation (more on potential EGCG liver toxicity later) was also shown to improve the function of our liver mitochondria and increase the redox potential of vitamins C, E, and glutathione. EGCG has also been shown to enhance the health of the mitochondria of our kidneys, protecting them from oxidative and nitrosative stress. EGCG also improved our heart mitochondria, preventing oxidative stress and “upregulating the activities of mitochondrial SOD, CAT (choline acetyltransferase), glutathione reductase, glutathione S-transferase, and GSH enzymes.” Finally, EGCG has also been shown to protect our heart mitochondria from the harmful effects of cigarette smoke and fluoride toxicity.[17] [18] [19] [20] [21] [22]

Limited evidence in studies has shown that epigallocatechin gallate improves mitochondrial biogenesis. EGCG increases mitochondrial DNA content and upregulates nuclear respiratory factor 1 (NRF-1) and dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), which all improve mitochondrial biogenesis. NRF-1 is a transcription factor that activates the expression of some key metabolic genes that regulate nuclear genes and cellular growth required for heme production, respiration, and mitochondrial DNA replication and transcription. DYRK1A participates in the modulation of CREB; Nuclear CREB regulates PGC-1α, the master regulator of mitochondrial biogenesis, and SIRT1, which is also essential for mitochondrial biogenesis and energy production, to favor mitochondrial biogenesis.[23] [24] [25]

Epigallocatechin gallate supplementation has benefits when appropriately used to improve your health, but it also has some side effects associated with its use. Chronic green tea ingestion has been found in a study to reduce thyroid hormone utilization within rats; possibly, the cause was debated if it was the caffeine, EGCG, or fluoride in the green tea that caused hypothyroidism. It is unknown if EGCG would worsen hypothyroidism. If you are borderline hypothyroid or suffering from hyperthyroidism, I would avoid supplementing with EGCG. EGCG supplementation may inhibit the COMT enzyme, but studies are mixed, so people with COMT V158M polymorphisms may want to reduce amounts supplemented or avoid its use because it may cause or increase symptoms, including anxiety, increased resting heart rate, and trouble sleeping from increased catecholamine circulation.[26] [27] [28]

Elevated doses of epigallocatechin gallate might harm our liver mitochondria and cause toxicity. Recently, high amounts of supplemental EGCG have been implicated in liver injury. A good recommendation for green tea consumption (one hundred and eighty milligrams per cup brewed, sixty milligrams per cup brewed decaffeinated, and ten to forty milligrams ready-to-drink green tea) is a max of eight hundred milligrams daily. For supplementation, less than eight hundred milligrams daily is recommended.[29] [30] [31]

Recommended Epigallocatechin Gallate Supplement

Dosage recommendation: Take one Designs for Health epigallocatechin gallate capsule upon awakening on an empty stomach and wait to eat breakfast for at least thirty minutes to an hour for maximum absorption.

[1] https://selfhacked.com/blog/worrier-warrior-explaining-rs4680comt-v158m-gene/

[2] https://www.researchgate.net/publication/12291145_Epicatechin_and_Catechin_are_O-Methylated_and_Glucuronidated_in_the_Small_Intestine

[3] https://www.ncbi.nlm.nih.gov/pubmed/27645804

[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4700981/

[5] https://www.ncbi.nlm.nih.gov/pubmed/22127270

[6] https://www.ncbi.nlm.nih.gov/pubmed/21303262

[7] https://selfhacked.com/blog/supplements-foods-exercise-right-type-th1-vs-th2-dominance/

[8] https://selfhacked.com/blog/th17/

[9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509513/

[10] https://www.ncbi.nlm.nih.gov/pubmed/22020144

[11] https://jim.bmj.com/content/64/8/1213

[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC89367/