Catechins
The antioxidant compounds responsible for tea's health-related effects.
Catechins are a class of polyphenol antioxidants concentrated in tea leaves. Matcha contains four main catechins: EGCG (the most studied), EGC, ECG, and EC. Total catechin content in matcha runs roughly 50 to 140 mg per gram, with EGCG making up about half. Because matcha is consumed as the whole ground leaf rather than steeped, you ingest more catechins per cup than from any infusion-only green tea — typically 2× to 3× more, not the 137× sometimes claimed in marketing.