Get Your Personalized Supplement StackSupplement Stack Quiz

Green Tea Leaf Egcg

Also known as: EGCG, Green Tea Catechin, Green Tea Polyphenol, Epigallocatechin gallate

Overview

Epigallocatechin gallate (EGCG) is the most abundant and biologically active catechin found in green tea leaves (Camellia sinensis). Classified as a polyphenolic flavonoid, EGCG is widely used as a dietary supplement ingredient due to its diverse health benefits. It is primarily recognized for its potent antioxidant, anti-inflammatory, and metabolic regulatory properties. Research indicates its utility in areas such as weight management, metabolic health improvement, and cardiovascular support. EGCG functions by scavenging free radicals, modulating inflammatory pathways, and influencing lipid and glucose metabolism. The body of research on EGCG is extensive, encompassing numerous randomized controlled trials, systematic reviews, and meta-analyses, providing a high level of evidence for many of its reported effects. While generally safe at recommended doses, its oral bioavailability can be moderate, and formulations may impact absorption.

Benefits

EGCG offers several evidence-based benefits, particularly for individuals with metabolic concerns. For weight and body composition, meta-analyses show that EGCG or green tea extract supplementation significantly reduces body mass, body fat percentage, and body mass index in overweight and obese adults, with moderate effect sizes. It also acts as a powerful antioxidant, increasing total antioxidant capacity and reducing markers of oxidative stress like malondialdehyde. While EGCG consistently decreases pro-inflammatory cytokine TNF-α levels, its effects on CRP and IL-6 are less consistent. In terms of glycemic control, systematic reviews report modest but significant improvements in fasting blood glucose, fasting insulin, HbA1c, and insulin resistance, supporting its role in metabolic regulation. Furthermore, green tea supplementation, rich in EGCG, has been shown to improve cardiovascular risk factors by reducing triglycerides and LDL cholesterol, and improving blood pressure parameters, with effects often being dose- and duration-dependent. Most robust evidence supports benefits in overweight/obese adults and those with metabolic syndrome or cardiovascular risk factors.

How it works

EGCG exerts its effects primarily through its potent antioxidant and anti-inflammatory properties. It scavenges free radicals, thereby reducing oxidative stress, and modulates key signaling pathways such as NF-κB and MAPK, which are involved in inflammation. Metabolically, EGCG influences lipid and glucose metabolism by enhancing fat oxidation and improving insulin sensitivity. It interacts with various enzymes and receptors, including those involved in adipokine regulation, such as adiponectin. While EGCG has moderate oral bioavailability, it undergoes first-pass metabolism, which can impact its systemic availability. Different formulations may be employed to enhance its absorption and efficacy within the body.

Side effects

EGCG is generally considered safe when consumed at physiological doses typically found in supplements. Mild side effects are rare. However, it is crucial to note that high doses of EGCG have been associated with elevated liver enzymes and, in susceptible individuals, potential hepatotoxicity. While no serious adverse events have been directly linked to EGCG in well-conducted randomized controlled trials, caution is advised. Drug interactions are possible, particularly with medications metabolized by liver enzymes, due to EGCG's potential influence on these pathways. Contraindications include pre-existing liver disease, and its use during pregnancy is not recommended unless under strict medical supervision due to insufficient safety data in this population. Similarly, there is a lack of comprehensive safety data for children and other special populations, warranting caution in these groups.

Dosage

Effective doses of EGCG, as observed in randomized controlled trials, typically range from 100 mg to 800 mg daily, often delivered as a green tea extract. The optimal dosage can vary depending on the desired health outcome; for weight loss and metabolic benefits, doses between 300–600 mg per day are commonly observed to be effective. While a maximum safe dose is not firmly established, doses exceeding 800 mg per day may increase the risk of liver toxicity, necessitating caution. The timing of EGCG supplementation is flexible, but taking it with meals may help mitigate potential gastrointestinal discomfort. Formulations designed to enhance bioavailability, such as EGCG combined with piperine, may allow for lower effective doses. No specific cofactors are required for EGCG's efficacy, but adequate hydration and, for higher doses, monitoring of liver function are recommended.

FAQs

Is EGCG safe long-term?

Generally, EGCG is safe at moderate doses for long-term use. However, long-term safety data for very high doses are limited, and monitoring is prudent.

How soon do effects appear?

Benefits on body composition and metabolic markers typically become noticeable within 4 to 16 weeks of consistent EGCG supplementation.

Can EGCG cause liver damage?

Rarely, high doses of EGCG have been linked to elevated liver enzymes and potential liver damage in susceptible individuals. Monitoring is advisable.

Does EGCG work alone or only in green tea?

Both isolated EGCG and green tea extracts demonstrate benefits. While EGCG is a key active compound, whole green tea contains other synergistic compounds.

Is it effective for weight loss?

Yes, EGCG can contribute to weight loss, but its effects are modest and are most effective when combined with comprehensive lifestyle changes.

Research Sources

https://www.alzdiscovery.org/uploads/cognitive_vitality_media/EGCG-Cognitive-Vitality-For-Researchers.pdf – This meta-analysis reviewed 11 RCTs on green tea catechins, including EGCG, in overweight/obese individuals. It found that EGCG reduced the inflammatory marker TNF-α but had inconsistent effects on CRP or IL-6. The safety profile was generally favorable with mild side effects, though high doses were linked to liver enzyme elevations. The review also incorporated findings from three Cochrane meta-analyses supporting the safety and modest weight loss effects of EGCG.
https://pubmed.ncbi.nlm.nih.gov/38031409/ – This meta-analysis included 59 randomized controlled trials (n=3802) investigating the effects of green tea extract on body composition and oxidative stress. It reported significant reductions in body mass, BMI, and body fat percentage, along with decreased malondialdehyde (an oxidative stress marker) and increased adiponectin and total antioxidant capacity. The study noted heterogeneity among studies but concluded with evidence certainty ranging from low to high for various outcomes.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7350188/ – This systematic review and meta-analysis focused on the impact of green tea supplementation on glycemic control. It analyzed randomized controlled trials and found statistically significant improvements in fasting glucose, insulin, HbA1c, and insulin resistance (HOMA-IR). The included studies generally had adequate participant numbers (30+ per group), proper controls, and low heterogeneity, strengthening the evidence for EGCG's role in glucose regulation.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.1084455/full – This systematic review investigated the effects of green tea supplementation on cardiovascular risk factors. It identified improvements in lipid profiles, specifically reductions in triglycerides and LDL cholesterol, and positive effects on blood pressure parameters. The review highlighted that these benefits were often dose- and duration-dependent, with statistical significance achieved in well-powered randomized controlled trials, supporting EGCG's role in cardiovascular health.