Green tea and catechins
One of the best-evidenced botanical antioxidants, at an unusually high inclusion in this range — and a stability problem worth understanding.
What is green tea and catechins?
Green tea (Camellia sinensis) is rich in catechins, principally epigallocatechin gallate (EGCG), along with epicatechin, epigallocatechin and epicatechin gallate. EGCG is the most studied and most active, and green tea polyphenols are among the better-evidenced botanical antioxidants in dermatology.
What it does
Antioxidant activity is the foundation, with additional reported anti-inflammatory activity and effects on sebum. There is reasonable evidence for photoprotective benefit when applied before UV exposure — reducing erythema and markers of oxidative damage — which places green tea in the small group of botanicals with a genuine protective rationale rather than only an antioxidant one.
For scalp use, catechins have been studied in relation to follicle biology, though this is considerably less settled than the antioxidant work.
The inclusion here is notable
Vegalab's Scalp Repair Shampoo uses 65% Jeju green-tea water in place of purified water. That is a formulation decision rather than an additive one, and it is unusual — most green tea claims rest on an extract at a fraction of a percent. Replacing the water phase means the catechin content is a function of the tea water's own concentration, so the meaningful figure is the catechin level in that water, which is worth stating if available.
By contrast, Youlief's Setup Cream lists Camellia sinensis leaf water at 0.00035% and declares it as a fragrance ingredient — a trace presence, and not a basis for an antioxidant claim.
The stability problem
Catechins oxidise readily, particularly at neutral to alkaline pH and in the presence of light and metal ions. Oxidised catechins are less active and cause the browning familiar from stewed tea. So a green tea product's real catechin content depends on pH, packaging and age, and a high stated inclusion at manufacture is not the same as a high content at use.
What does green tea and catechins not do?
It is not a sunscreen and does not replace one. Effects are preventive rather than corrective. And oral green tea consumption is a separate question from topical application.