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Formally known as epigallocatechin gallate, EGCG is a type of plant-based compound called catechin. Catechins may be further categorized into a larger group of plant compounds known as polyphenols (1Trusted Source).
EGCG and other related catechins act as potent antioxidants that may protect against cellular damage caused by free radicals (1Trusted Source).
Epigallocatechin gallate, or EGCG, is a polyphenol found in green tea along with catechin, epicatechin, proathocyanidins and others. A typical cup of tea brewed from dried leaves yields about 300 to 400 mg of polyphenols, but only a small portion of that is EGCG, which is considered the most beneficial compound of the group.
Epigallocatechin gallate possess the most potent antioxidant activity of the catechins. Epigallocatechin gallate may provide health effects by protecting our cells from oxidative damage from free radicals. A number of chronic disease have been associated with free radical damage, including cancer, arteriosclerosis, heart diseases and accelerated aging. Epigallocatechin gallate interferes with many enzyme systems: it inhibits fast-binding and reversible fatty acid synthase, increases tyrosine phosphorylation of the insulin receptor, activation of ornithine decarboxylase.
Epigallocatechin gallate may be effective in promoting fat oxidation and lowering body weight.
EGCG may also promote weight loss, especially when taken alongside the caffeine naturally found in green tea.
Although much of the study results on EGCG’s effect on weight are inconsistent, some long-term observational research noted that consuming about 2 cups (14.7 ounces or 434 ml) of green tea per day was associated with lower body fat and weight (11Trusted Source).
Additional human studies have collectively found that taking 100–460 mg of EGCG together with 80–300 mg of caffeine for at least 12 weeks is linked to significant weight loss and reduction of body fat (12Trusted Source).
Still, changes in weight or body composition are not consistently seen when EGCG is taken without caffeine.
The benefits of green tea catechins on lipid oxidation and related fat-burning pathways are achieved in a dose dependent manner. Significant effects in humans are noted only at high doses, such as 400-500mg EGCG equivalent per day (most Green Tea Extract supplements are roughly 50% EGCG). Fat burning effects are highly synergistic, almost dependent, on not consuming caffeine habitually.
Research has shown that EGCG may help increase calorie burn and help the body use stored fat for energy, although the exact mechanism is unclear. A 2000 study at the University of Chicago showed that rats reduced their calorie intake by 60 percent after seven daily EGCG injections, allowing them to lose 21 percent of their body weight. Researchers believe that the EGCG may alter the levels of “hunger hormones,” thus reducing the appetite. The catch is that the rats were given an injection of EGCG, and the results were not as promising when the EGCG was given orally. It is unclear whether the body may not absorb EGCG fully from the digestive tract, but if an oral extract didn’t work, that leaves little hope for the lower concentrations provided by oral tea consumption.
(-)-Epigallocatechin-3-gallate (EGCG), which is the most abundant catechin in green tea, has many potential health benefits, including decreased weight gain and/or adipose tissue weight. Suggested mechanisms for body weight reduction by EGCG include: (1) a decrease in calorie intake and (2) activation of AMPK in liver, skeletal muscle, and white adipose tissue. However, only one study supports the AMPK hypothesis. To determine the role of AMPK in EGCG-induced reduction of body weight, we administrated 50 mg/kg and 100 mg/kg per day to mice, together with a high-fat diet (HFD), for 20 weeks. EGCG had a significant effect on obesity and decrease in epididymal adipose tissue weight, and also affected serum lipid characteristics, including triglyceride, cholesterol (CHOL), and high- and low-density lipoprotein CHOL (HDL-C, LDL-C) concentrations. In addition, EGCG increased the excretion of free fatty acids from feces. By measuring the mRNA expression levels of genes involved in lipid metabolism, we found that EGCG inhibited the expression of genes involved in the synthesis of de novo fatty acids (acc1, fas, scd1, c/ebpβ, pparγ, and srebp1) and increased the expression of genes associated with lipolysis (hsl) and lipid oxidization in white adipose tissue, in both the HFD and the EGCG groups. However, EGCG significantly increased the expression of genes involved in the synthesis of de novo fatty acids compared with the HFD group. Increased AMPK activity was found in both subcutaneous and epididymal adipose tissues. In conclusion, EGCG can decrease obesity and epididymal white adipose tissue weight in mice, only partially via activation of AMPK.
Researchers found that a compound in green tea called epigallocatechin gallate (EGCG) reduced the development of insulin resistance, obesity, and memory impairments in mice fed a high-fat, high-fructose diet.
Study co-author Xuebo Liu, Ph.D., of the College of Food Science and Engineering at Northwest A&F University in China, and colleagues recently reported their findings in The FASEB Journal.
The Western diet is generally defined as a diet rich in red and processed meats, high in saturated fats, refined sugars, and refined carbohydrates, and low in fruits, vegetables, whole grains, seafood, and poultry.
The new study, however, suggests that the green tea compound EGCG could help to protect against the harms of a Western diet.
At the end of the 16-week study period, as expected, the mice fed the HFFD had gained more weight than the control group. However, the weight gain was much less severe for mice whose HFFD was supplemented with EGCG.
Green tea has been studied extensively for its antimicrobial properties. In particular, matcha’s main catechin, EGCG, has demonstrated activity against a number of viruses, bacteria, and fungi. EGCG has shown activity against diverse families of viruses, including Retroviridae, Orthomyxoviridae, and Flaviviridae, as well as significant pathogens such as HIV, influenza A, and hepatitis C. In in vitro studies, EGCG interfered with the replication cycle of DNA viruses like hepatitis B, herpes simplex, and adenovirus. In addition, EGCG (alone and in combination with different antibiotics) has shown activity against a number of bacteria, including multidrug-resistant strains such as methicillin-resistant Staphylococcus aureus and Stenotrophomonas maltophilia. EGCG has also demonstrated antifungal activity against human pathogens like Candida albicans and Fusobacterium nucleatum.
Providing EGCG is a pharmakon (ancient Greek word meaning at the same time remedy and poison), side effects should also be expected. There is an important lack of clinical studies referring to dose levels for different diseases, daily administration frequency and side effects in long term therapy. A daily dose of 800 mg caffeine free EGCG for 4 weeks was shown to be safe and well tolerated in healthy human subjects . However, inherent to different effects of EGCG in several levels, and due to possible contamination with herbicides and/or pesticides, some degree of side effects can be expected:
4.1. Anxiolytic Activity
EGCG produces some behavioral effects corresponding to a benzodiazepine-like profile, inducing anxiolytic activity which could result from an interaction with γ-aminobutyric acid (GABAA) receptors [35–37].
4.2. Hypoglycemic Activity
EGCG suppresses hepatic gluconeogenesis at concentrations that are not toxic to hepatocytes and are reachable by ingestion of green tea or pure EGCG through 5′-AMP-activated protein kinase mediated by the Ca2+/calmodulin-dependent protein kinase, both dependent on production of reactive oxygen species .
4.3. Hypochromic Anemia
Phenolic compounds such as EGCG are potent inhibitors of iron absorption in a dose-dependent fashion depending on the content of total polyphenols, interfering with its assimilation by the complex formation of the gastro-intestinal lumen [41–43].
4.4. Liver and Kidney Failure
A daily dose of 800 mg caffeine free EGCG for 4 weeks was shown to be safe and well tolerated in healthy human subjects .