The main catechins in matcha
Catechins are flavan-3-ol polyphenols. The principal types discussed in green tea are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC). EGCG and ECG contain a gallate group; EGC and EC do not.
These compounds contribute to bitterness and astringency and react in laboratory antioxidant assays. Those properties explain their importance in tea chemistry without making matcha a treatment or assigning a separate clinical benefit to each catechin.
How to read catechin measurements
EGCG is often described as the major catechin in green tea, but a fixed percentage should not be applied to every matcha. Compare the tested sample, extraction method and reporting basis before comparing amounts.
Milligrams of a named catechin are not interchangeable with milligrams of gallic acid equivalents, or GAE. GAE expresses a total-phenolic assay relative to a reference substance; it is not the measured mass of EGCG or the sum of named catechins. Nor does either result state the amount immediately absorbed by a person.
Matcha is consumed as powdered leaf, whereas an ordinary infusion leaves solids behind. A 2003 study used different extraction methods to examine this distinction. Its large EGCG comparison against one tea product does not establish a universal catechin advantage for every serving or grade.
Flavor and cultivation
Gallated catechins are relevant to tea astringency, but other flavonoids also matter. Sensory verification in a two-cultivar matcha study implicated EGCG and several quercetin and kaempferol glycosides.
Shading changes leaf chemistry rather than raising every constituent together. In a Fuding white tea experiment, shading increased theanine and caffeine but decreased EC and EGC. A commercial grade name does not quantify the resulting catechin profile.
Storage and preparation
A two-month matcha storage study found declining catechin content and radical-scavenging assay activity as temperature and time increased. Keeping powder sealed and away from heat, light and moisture is a practical quality precaution, not a guarantee of unchanged composition.
Preparation affects the liquid and sensory experience, but cold water does not remove compounds from the powder you swallow. The storage study does not establish a precise brewing temperature that guarantees the greatest health benefit.
What health evidence can support
Antioxidant assays test chemical behavior under laboratory conditions. They do not show that drinking matcha prevents cancer, reduces arterial disease, treats diabetes or protects against dementia. Animal and isolated-extract results require separate interpretation from whole-matcha human studies.
NCCIH reports that evidence is inconclusive for most promoted green-tea uses. Some cholesterol trials found small changes, but most tested extracts rather than tea as a beverage. Matcha contains caffeine, and concentrated green-tea extracts have been linked to uncommon liver injury. Neither a catechin amount nor a bitter taste establishes effectiveness or safety.
