Green Tea Extract

Green tea extract comes from the unfermented leaves of Camellia sinensis, the same plant that produces black and oolong tea. The difference between them is oxidation, and it matters for skincare because oxidation destroys the compounds of interest.

The active constituents

Green tea's activity is attributed largely to catechins, a group of polyphenols. The most studied is epigallocatechin gallate, usually shortened to EGCG, which typically makes up the largest share of the catechin content.

Because black tea leaves are fully oxidised, their catechin content is substantially lower. Green tea is used in cosmetics for that reason rather than for any preference of flavour.

How it works

Catechins are potent antioxidants, scavenging free radicals generated by UV exposure and pollution. Research has also associated EGCG with anti-inflammatory activity, and with an effect on sebum, which is why green tea appears in formulations aimed at oily and congested skin.

It contains caffeine as well, which has mild vasoconstrictive properties, part of why green tea extract turns up in eye products.

The stability problem

Catechins oxidise readily on exposure to air, light and heat, which is the practical limitation on this ingredient. A green tea extract that has degraded in the bottle contributes nothing.

This makes formulation and packaging more consequential than concentration. A well-stabilised extract in opaque packaging is worth more than a higher percentage in a clear jar.

Extract is not standardised

"Camellia sinensis leaf extract" on an ingredient list tells you the plant and the part used. It does not tell you the extraction method, the solvent, or the catechin content, and these vary enormously between suppliers.

Two products listing the same INCI name can differ by an order of magnitude in actual polyphenol content. This is a general limitation of botanical extracts rather than a criticism of any particular product.