EGCG

• Antioxidant protection
• Cellular signaling modulation
• Metabolic health
• Cardiovascular support

• Weight management
• Cognitive function
• Liver health
• Skin protection
• Oral health
• Cancer risk reduction
• Immune function

EGCG (epigallocatechin gallate) exerts its diverse biological effects through multiple mechanisms at the molecular level. As a powerful antioxidant, EGCG directly neutralizes reactive oxygen species (ROS) and free radicals through its hydroxyl groups, which donate hydrogen atoms to stabilize these harmful molecules. Beyond direct antioxidant activity, EGCG upregulates endogenous antioxidant defense systems by activating nuclear factor erythroid 2-related factor 2 (Nrf2), which increases the expression of antioxidant enzymes like glutathione peroxidase, catalase, and superoxide dismutase. EGCG exhibits potent anti-inflammatory effects by inhibiting nuclear factor-kappa B (NF-κB) activation, reducing the production of pro-inflammatory cytokines like tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6).

It also inhibits cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), further reducing inflammatory mediator production. In metabolic pathways, EGCG enhances energy expenditure and fat oxidation by inhibiting catechol-O-methyltransferase (COMT), the enzyme that degrades norepinephrine, thereby prolonging sympathetic stimulation of thermogenesis. It also activates AMP-activated protein kinase (AMPK), a master regulator of cellular energy homeostasis that promotes glucose uptake and fatty acid oxidation while inhibiting lipogenesis. EGCG improves insulin sensitivity by enhancing insulin receptor substrate (IRS) signaling and GLUT4 translocation to cell membranes, facilitating glucose uptake into cells.

In the cardiovascular system, EGCG enhances nitric oxide production by activating endothelial nitric oxide synthase (eNOS), promoting vasodilation and improving blood flow. It inhibits angiotensin-converting enzyme (ACE), helping to regulate blood pressure, and reduces the oxidation of LDL cholesterol, a key step in atherosclerosis development. EGCG modulates numerous cell signaling pathways, including JAK/STAT, MAPK, PI3K/Akt, and Wnt/β-catenin, influencing cell proliferation, differentiation, and survival. This contributes to its potential anti-cancer effects, along with its ability to induce cell cycle arrest and apoptosis in cancer cells while generally sparing normal cells.

In the brain, EGCG crosses the blood-brain barrier and exhibits neuroprotective effects by reducing oxidative stress, inhibiting monoamine oxidase (MAO), and modulating neurotransmitter systems. It promotes neurogenesis and enhances brain-derived neurotrophic factor (BDNF) levels, supporting neuronal health and plasticity. EGCG also inhibits the formation of amyloid-β and tau protein aggregates, which may explain its potential benefits for neurodegenerative conditions. At the epigenetic level, EGCG inhibits DNA methyltransferases (DNMTs) and histone deacetylases (HDACs), potentially reversing aberrant epigenetic modifications associated with various diseases.

It also interacts with and modulates the function of numerous cellular receptors, including the 67-kDa laminin receptor, which may mediate many of its biological effects. Additionally, EGCG exhibits antimicrobial properties by damaging bacterial cell membranes and inhibiting biofilm formation, while also showing antiviral effects by binding to viral proteins and inhibiting viral attachment to host cells.

No Recommended Dietary Allowance (RDA) or Adequate Intake (AI) has been established for EGCG, as it is not considered an essential nutrient. Based on clinical studies, effective doses typically range from 100-500 mg of EGCG per day for general health benefits. This is equivalent to approximately 2-5 cups of brewed green tea daily, as a cup of green tea typically contains 30-100 mg of EGCG depending on brewing method and tea quality. For specific therapeutic purposes, doses up to 800 mg of EGCG daily have been used in research settings, though doses above 800 mg may increase the risk of side effects.

Most commercial green tea extract supplements provide 100-400 mg of EGCG per serving.

EGCG has relatively poor oral bioavailability, with estimates ranging from 0.1% to 12% of an ingested dose reaching systemic circulation in humans. Several factors contribute to this limited bioavailability: EGCG is unstable in the acidic environment of the stomach, with significant degradation occurring before reaching the intestines; it has limited intestinal permeability due to its large molecular size and hydrophilic nature; it undergoes extensive first-pass metabolism in the intestinal mucosa and liver, where it is conjugated through methylation, sulfation, and glucuronidation; and it is subject to efflux back into the intestinal lumen via P-glycoprotein and multidrug resistance proteins. Additionally, EGCG can bind to proteins in the digestive tract and form complexes with dietary components like calcium and iron, further reducing absorption. Once absorbed, EGCG has a relatively short plasma half-life of approximately 3-5 hours, with peak plasma concentrations typically occurring 1.5-2 hours after ingestion.

The bioavailability of EGCG from supplements is generally higher than from brewed green tea, particularly when taken in fasted conditions, though still relatively low compared to many other dietary supplements.

Taking with piperine (black pepper extract) can inhibit intestinal and hepatic glucuronidation of EGCG, potentially increasing bioavailability by 30-60%, Consuming with dietary fats may enhance absorption, though evidence is mixed, Liposomal and phytosomal formulations can increase bioavailability 2-3 fold by protecting EGCG from degradation and enhancing cellular uptake, Taking on an empty stomach generally improves absorption compared to taking with meals (contrary to many other supplements), Consuming with vitamin C may enhance stability and reduce oxidation in the digestive tract, Quercetin may inhibit the methylation of EGCG, potentially extending its half-life, Buffered or pH-modified formulations can protect EGCG from degradation in stomach acid, Nanoparticle and microencapsulation technologies can significantly improve bioavailability, Consuming as matcha (powdered whole green tea leaves) may provide better absorption due to the presence of the entire leaf matrix, Taking multiple smaller doses throughout the day rather than a single large dose may result in higher overall absorption and more consistent blood levels

For general health benefits, EGCG can be taken at any time of day, though absorption may be slightly better on an empty stomach, 30-60 minutes before meals. For weight management, taking EGCG 30-60 minutes before exercise may enhance fat oxidation during physical activity. When using EGCG for its thermogenic effects, morning dosing may be preferable to avoid potential sleep disturbances from the mild stimulant effect, particularly if the supplement also contains caffeine. For blood glucose management, taking EGCG 30-60 minutes before meals may help moderate postprandial glucose spikes.

To minimize potential iron-binding effects, EGCG should be taken at least 2 hours before or after iron-containing foods or supplements, particularly important for those with iron deficiency. For those sensitive to caffeine or using decaffeinated green tea extracts, evening dosing is acceptable and may provide antioxidant support during overnight metabolic processes. When using multiple daily doses, spacing them at least 4-6 hours apart may help maintain more consistent blood levels throughout the day. Consistency in daily supplementation is generally more important than specific timing, as many of EGCG’s benefits develop through regular, long-term use.

• Gastrointestinal discomfort (nausea, stomach pain, constipation, diarrhea) – most common side effect, particularly at higher doses
• Caffeine-related effects when consumed as green tea or non-decaffeinated extracts (insomnia, anxiety, increased heart rate, headache)
• Iron absorption reduction (may contribute to iron deficiency in susceptible individuals)
• Mild headache
• Dizziness (uncommon)
• Potential for liver enzyme elevation at very high doses (>800 mg EGCG daily)
• Rare cases of liver injury with concentrated supplements (primarily with fasting or multiple daily doses)
• Potential for reduced absorption of certain medications
• Mild diuretic effect

• Liver disease or history of liver problems (use with caution and medical supervision)
• Iron deficiency anemia (may worsen condition)
• Bleeding disorders (due to potential antiplatelet effects)
• Anxiety disorders or sensitivity to caffeine (for non-decaffeinated sources)
• Pregnancy and breastfeeding (high doses; moderate tea consumption is generally considered safe)
• Scheduled surgery (discontinue 2 weeks before due to potential blood-thinning effects)
• Severe cardiovascular conditions (for products containing caffeine)
• Known hypersensitivity to green tea or its components

• Anticoagulant/antiplatelet medications (potential additive effect increasing bleeding risk)
• Iron supplements (reduced absorption if taken simultaneously)
• Stimulant medications (additive effects with caffeine-containing green tea products)
• Nadolol and potentially other beta-blockers (EGCG may reduce absorption)
• Certain chemotherapy drugs (variable interactions; may enhance effects of some while potentially interfering with others)
• Hepatotoxic medications (potential additive risk at high EGCG doses)
• Drugs metabolized by CYP3A4 enzymes (potential interaction at high doses)
• MAO inhibitors (with caffeine-containing products)
• Bortezomib (EGCG may reduce efficacy)
• Lithium (caffeine in green tea products may affect levels)

No official Tolerable Upper Intake Level (UL) has been established for EGCG. Based on available research and case reports, doses up to 800 mg EGCG per day appear generally safe for most healthy adults for extended use. The European Food Safety Authority (EFSA) has suggested that supplements providing more than 800 mg EGCG per day may pose potential health concerns. Liver-related adverse events have been primarily associated with doses exceeding 800 mg EGCG daily, when taken in fasted conditions, or with multiple daily doses that maintain high blood levels.

Green tea beverages are generally considered safe even with regular, high consumption (10+ cups daily in some populations), suggesting that the matrix in which EGCG is consumed affects its safety profile. Individuals with liver conditions, on multiple medications, or with other health concerns should use lower doses and consult healthcare providers. As with any supplement, it’s prudent to use the lowest effective dose for the intended purpose, particularly for long-term use.

EGCG is not specifically approved as a food additive by the FDA, but green tea extract containing EGCG is Generally Recognized as Safe (GRAS) for use as an ingredient in foods and beverages. As a dietary supplement ingredient, EGCG falls under the regulations of the Dietary Supplement Health and Education Act (DSHEA) of 1994. The FDA has not approved specific health claims for EGCG or green tea extract supplements. In 2018, the FDA issued a statement expressing concern about potential liver injury associated with high-dose green tea extract supplements, particularly when taken on an empty stomach.

This was not a ban or restriction but a caution to consumers and industry. Green tea as a traditional beverage is recognized by the FDA as safe for consumption.

Eu: The European Food Safety Authority (EFSA) has evaluated green tea catechins and established safety guidelines. In 2018, EFSA concluded that green tea supplements providing more than 800 mg EGCG per day may pose potential health concerns related to liver function. EFSA has rejected most health claims for green tea extracts due to insufficient evidence meeting their standards, though they acknowledge green tea’s antioxidant properties. As a food ingredient, green tea extract is permitted with certain limitations.

Japan: Green tea extracts have a special status in Japan as ‘Foods for Specified Health Uses’ (FOSHU) for certain applications. Japan has approved specific health claims for some standardized green tea catechin products, particularly related to body fat reduction. Japan’s regulatory framework recognizes green tea’s traditional use and has been more accepting of its health benefits in official capacities than Western regulatory bodies.

Canada: Health Canada has approved green tea extract as a Natural Health Product (NHP) ingredient with authorized claims related to its antioxidant properties and traditional use. Health Canada has established specific monographs for green tea extracts that specify quality requirements and permitted claims.

Australia: The Therapeutic Goods Administration (TGA) regulates green tea extracts as listed complementary medicines. The TGA has issued safety advisories similar to other regulatory bodies regarding potential liver concerns with concentrated extracts, recommending that products containing EGCG include warning statements about potential liver effects.

China: Green tea is officially listed in the Chinese Pharmacopoeia and recognized for its traditional medicinal properties. Concentrated EGCG extracts are regulated both as food ingredients and as components of traditional medicine formulations.

Low to moderate

$0.10-$0.50 per day for standard green tea extracts (200-400 mg EGCG); $0.50-$1.50 per day for enhanced bioavailability formulations; $0.05-$0.20 per day for brewed green tea (3-5 cups)

EGCG offers excellent value compared to many other supplements, providing multiple evidence-based health benefits at relatively low cost. Standard green tea extracts standardized to 45-50% EGCG content provide the most economical option for most users, delivering clinically relevant doses at minimal expense. For those seeking specific benefits like weight management or metabolic support, the combination of EGCG with caffeine (either naturally in green tea extract or as added caffeine) typically offers the best value, as this combination has the strongest research support. Enhanced bioavailability formulations command premium prices but may offer superior value for certain applications, particularly neurological and cardiovascular benefits where systemic absorption is critical.

These formulations may allow for lower doses while achieving similar blood levels of active compounds. For general health maintenance and antioxidant support, consuming green tea as a beverage provides exceptional value, delivering not only EGCG but also other beneficial compounds in green tea like L-theanine, other catechins, and trace minerals. High-quality loose-leaf green tea can provide 100-200 mg of EGCG per day at very low cost. Matcha (powdered whole green tea leaves) offers particularly good value as it contains higher EGCG levels than brewed tea and includes beneficial compounds from the entire leaf.

When comparing products, calculate the cost per milligram of EGCG rather than per capsule, as potency varies widely between brands. Decaffeinated green tea extracts typically cost 20-30% more than regular extracts but provide an important option for those sensitive to caffeine or taking EGCG in the evening. For specific therapeutic applications, the value should also consider potential cost savings from reduced need for other interventions. For example, EGCG’s benefits for metabolic health might reduce reliance on other supplements or medications, providing additional value beyond the direct cost.

Properly formulated and packaged EGCG supplements typically have a shelf life of 18-36 months. EGCG is relatively unstable compared to many other supplement ingredients, particularly in solution or when exposed to environmental factors. Dry extract powders in capsules or tablets generally maintain potency longer than liquid formulations. Enhanced bioavailability formulations may have different stability profiles depending on the specific technology used.

Manufacturers often add stabilizers like vitamin C or citric acid to extend shelf life.

Store in a cool, dry place away from direct light and heat (below 25°C/77°F). EGCG is particularly sensitive to heat and light degradation, so opaque containers are essential. Keep containers tightly closed to prevent moisture exposure, as EGCG is also susceptible to hydrolysis in moist conditions. Refrigeration is recommended for liquid formulations and may extend shelf life of all EGCG products, particularly after opening.

Avoid freezing liquid formulations unless specifically recommended by the manufacturer. For brewed green tea, consume fresh when possible; refrigerated tea maintains most EGCG content for 1-2 days if stored in an airtight container.

Heat (accelerates oxidation and epimerization; significant degradation occurs above 40°C/104°F), Light exposure (particularly UV light, causes rapid degradation), Oxygen exposure (leads to oxidation), Alkaline conditions (EGCG is highly unstable above pH 7), Moisture (promotes hydrolysis), Transition metals (iron, copper can catalyze oxidation), Enzymes in saliva and digestive tract (polyphenol oxidases, esterases), Microbial contamination (more relevant for liquid formulations)

Synthesis Methods

Natural Sources

Quality Considerations

While EGCG itself was not isolated and identified until the 20th century, green tea, its primary source, has one of the longest and richest histories of any medicinal plant. According to legend, green tea was discovered in China in 2737 BCE when Emperor Shennong experienced leaves from a wild tea tree falling into his boiling water. The earliest written records of tea consumption for health date to the 3rd century CE in China, where it was initially used as a medicinal beverage before becoming a daily drink. The first comprehensive text on tea, ‘The Classic of Tea’ (茶經) by Lu Yu, was written during the Tang Dynasty (618-907 CE) and described tea’s medicinal properties.

In Traditional Chinese Medicine, green tea was prescribed for headaches, digestive issues, detoxification, and to enhance longevity. It was considered a superior tonic that could ‘brighten the eyes,’ improve thinking, and delay aging. Buddhist monks embraced tea to maintain alertness during meditation, spreading its use throughout East Asia. Green tea reached Japan around the 9th century CE, brought by Japanese monks who had studied in China.

It became integral to Japanese culture, with the development of the tea ceremony (chado) in the 15th century under the influence of Zen Buddhism. In Japanese Kampo medicine, green tea was used to clear heat, remove toxins, improve digestion, and promote longevity. Korean traditional medicine similarly employed green tea for its cooling properties and detoxifying effects. Western awareness of green tea began in the 16th century through Portuguese missionaries and traders, though it remained exotic and expensive in Europe until the 17th century.

The modern scientific study of green tea catechins began in the 1930s, with initial isolation of catechin compounds. EGCG itself was first isolated and characterized in the 1940s, though its specific structure wasn’t fully elucidated until later. The term ‘epigallocatechin gallate’ was established in scientific literature by the 1960s. Significant research into EGCG’s health benefits began in the 1970s and 1980s, with Japanese researchers leading many early studies on its antioxidant properties and potential cancer-preventive effects.

The 1990s saw an explosion of research into EGCG’s molecular mechanisms, particularly after epidemiological studies in Japan and China suggested lower cancer rates among green tea drinkers. The first EGCG-standardized supplements became commercially available in the late 1990s, initially marketed primarily for weight management and antioxidant protection. By the early 2000s, research expanded to explore EGCG’s effects on cardiovascular health, metabolism, and neurodegenerative conditions. Today, EGCG is one of the most extensively researched natural compounds, with thousands of published studies exploring its diverse biological activities and potential applications in chronic disease prevention.

EGCG for prevention of cognitive decline in older adults, Green tea extract for non-alcoholic fatty liver disease, EGCG as adjunctive therapy for metabolic syndrome, Topical EGCG formulations for skin photoprotection and aging, EGCG for exercise performance and recovery, Green tea catechins for oral health and prevention of periodontal disease, EGCG’s effects on gut microbiome composition and function, Combination of EGCG with other polyphenols for synergistic effects, EGCG for endothelial function and cardiovascular risk markers, Green tea extract for weight management in specific populations