Does green tea help your gut health?

Green tea contains polyphenols, of which EGCG is the best known. EGCG makes up roughly half of all polyphenols in green tea. It is absorbed in the gut and partly converted by gut bacteria, after which it can influence fat metabolism and inflammatory processes. Most of the evidence for this comes from laboratory and animal studies; in humans this has so far been confirmed only to a limited extent.

A large cohort study of nearly 1,800 people found that regular tea consumption was associated with more favourable levels of certain gut bacteria and bile acids, which also play a role in cardiovascular health. This concerns tea in general, not green tea alone, and it is an association study: the fact that people with more favourable gut bacteria drink more tea does not automatically mean that tea is the cause.

A small randomised study using matcha (green tea in powder form, twice daily for eight to twelve weeks) observed changes in five groups of gut bacteria in healthy men. Three of those changes were associated with increases in muscle strength. The study was small and partly funded by Nestlé Japan, which calls for some caution in interpreting the results.

A literature review of 106 studies identified green tea as a dietary component that is beneficial for the composition of the gut microbiota. The supporting evidence is, however, indirect: higher tea consumption was associated with higher urinary markers that reflect gut diversity, but the bacterial populations themselves were not directly measured in that review.

What you can practically take from this: green tea fits well into a varied diet that supports the gut in other ways too, such as through fibre and fermented products. There is no evidence that you need a specific dose or form (such as matcha) to obtain gut benefits. Do not expect major changes from green tea alone.