# Pharmacokinetics & Metabolism EGCG is the main catechin in **green tea**, but its biggest practical limitation in oncology is poor oral bioavailability. ### Bioavailability Systemic oral bioavailability is very low. Main reasons include: * poor stability in the intestinal environment * limited absorption * extensive first-pass metabolism * rapid conjugation and elimination This is one reason EGCG may be more reliable for local gastrointestinal effects than for high systemic exposure using standard oral dosing. ### Major metabolism pathways EGCG is handled mainly through phase II pathways, including: * catechol-O-methyltransferase (COMT) * UDP-glucuronosyltransferases (UGT) * sulphotransferases (SULT) CYP enzymes appear to play a secondary but still relevant role in practical interaction discussions. ### CYP3A4 interaction relevance EGCG is not mainly cleared through CYP3A4, but it still comes up in interaction discussions because it may inhibit CYP3A4 in preclinical systems. Human data are more mixed, which is why it is best framed as a **possible interaction modifier**, not a predictable strong inhibitor in every real-world setting. For a treatment-specific example, see [Natural Compounds and CYP3A4 — HER2CLIMB Considerations](/myhealingcommunity-docs/breast-cancer/her2-positive/her2climb/natural-compounds-and-cyp3a4-her2climb-considerations.md). ### Strategies that may improve exposure * fasting administration may improve absorption compared with fed use * liposomal and nanoparticle formulations may improve stability and delivery * dairy may reduce absorption because catechins bind proteins ### Half-life and practical implication EGCG has a relatively short half-life, which is one reason divided dosing often makes more sense than single-bolus use. ### Key References Epigallocatechin-3-gallate at the nanoscale: a new strategy to overcome barriers to anti-tumour activity\ Anticancer Molecular Mechanisms of Epigallocatechin-3-Gallate (EGCG)\ Anticancer effects of epigallocatechin-3-gallate nanoemulsion on lung cancer cells\ {% hint style="warning" %} This information is for education only. It is not medical advice, diagnosis, or treatment. Please speak with a qualified clinician before making changes to care, medication, or supplement use. {% endhint %} {% hint style="info" %} © 2026 Abbey Mitchell. All rights reserved. Please share by URL rather than copying page text. {% endhint %} --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://myhealingcommunity.gitbook.io/myhealingcommunity-docs/natural-medicines/egcg-in-oncology/pharmacokinetics-and-metabolism.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.