Green tea
(catechins)
What it isCamellia sinensis leaf consumed as a beverage or concentrated extract, rich in catechins (notably EGCG) plus caffeine.
Why this oneUbiquitous as a drink and sold as high-dose weight-loss and antioxidant supplements, where concentrated extracts have been linked to idiosyncratic, sometimes serious hepatotoxicity.
What limits itIts catechins inhibit intestinal OATP and efflux transporters, markedly lowering absorption of substrates such as nadolol, while its vitamin K content can blunt warfarin's effect.
NO BOXED WARNINGS
Principal riskNo FDA boxed warning.