EGCG / Green Tea Extract

How it works

EGCG (epigallocatechin-3-gallate) is the most abundant catechin in green tea. It helps modulate NF-κB and STAT3 signalling, neutralises reactive oxygen species and supports epithelial barrier function. Most EGCG isn’t absorbed into the bloodstream, so it reaches high concentrations in the gut itself — a natural form of gut-targeted delivery that researchers find especially interesting for bowel inflammation.

Traditional use

Green tea has been consumed in China and Japan for thousands of years and is deeply woven into East Asian health traditions as a daily tonic for digestion and vitality.

Highlights

• In a placebo-controlled pilot, 66.7% of people with ulcerative colitis taking EGCG had a significant improvement in disease activity.
• Benefits were seen even in people who had not responded to 5-ASA or azathioprine.
• A case series reported improvement in hard-to-treat pouchitis.
• Naturally concentrates in the gut rather than circulating widely.
• Concentrated extracts should be taken with food, as high-dose extracts taken fasting have been linked to liver stress.

What the research shows

Every study below links to its original publication so you can read it yourself. Many natural compounds have only been studied in small trials. That isn’t a verdict on them; it reflects how little funding exists for compounds that can’t be patented.

Using it alongside conventional care

EGCG shares an elegant design principle with Entyvio. Entyvio was engineered to act on the gut without broad systemic effects, and EGCG naturally stays concentrated in the gut. In the ulcerative colitis pilot, it helped people who had not responded well to Mesalamine or Azathioprine. Many people start by simply drinking more green tea and move to a standardised extract with their care team’s input. Concentrated extract can reduce iron absorption and has rare links to liver stress, so take it with meals and ask about monitoring.

Never stop or change a prescribed medication without your gastroenterologist. Many people use natural support alongside conventional care, and your care team can help you do that safely.

Amounts used in research

The ulcerative colitis pilot used Polyphenon E providing 400 mg or 800 mg total EGCG daily in divided doses. Brewed green tea delivers roughly 50–100 mg of EGCG per cup — an entirely different exposure from concentrated extract capsules.

Good to know

• Concentrated green tea extract is a recognised cause of idiosyncratic acute liver injury, including cases requiring transplantation. This is the dominant safety consideration.
• Risk is materially higher when taken fasted and at high doses; brewed tea has not been implicated.
• EGCG chelates iron and reduces its absorption — a meaningful problem in a population where iron deficiency is the most common complication.
• Reduces the bioavailability of nadolol and some other drugs via OATP transporter inhibition.
• Liver enzyme monitoring is prudent for anyone taking concentrated extract, particularly alongside methotrexate or azathioprine.

Community experiences

Sources

1. 1

   A pilot study to evaluate the safety and efficacy of an oral dose of (-)-epigallocatechin-3-gallate-rich polyphenon E in patients with mild to moderate ulcerative colitis

   Dryden GW, Lam A, Beatty K, Qazzaz HH, McClain CJ. · Inflammatory Bowel Diseases · 2013 · PMID 23846486

2. 2

   Refractory pouchitis improves after administration of the green tea polyphenol EGCG: a retrospective review

   Cheifetz AS, et al. · International Journal of Colorectal Disease · 2017

3. 3

   Therapeutic effects of epigallocatechin-3-gallate for inflammatory bowel disease: a preclinical meta-analysis

   Preclinical meta-analysis · Phytomedicine · 2024