A systematic review and meta-analysis published in a recent issue of Molecules found an association between oral intake or topical application of green tea catechins and a reduction in ultraviolet (UV) radiation-induced sunburn, which is an inflammatory reaction of the skin to UV exposure, clinically known as erythema.*

Catechins are a type of flavonoid that occur in plants such as Camellia sinensis (tea). Green tea catechins include (-)-epigallocatechin-3-gallate (EGCG), well known for its anti-cancer and health-promoting effects, (-)-epicatechin, and many other similar molecules. These compounds have been recognized as having anti-inflammatory, antioxidant and photo-protective properties.

“To our knowledge, this is the first meta-analysis to assess the effectiveness of green tea catechins specifically on measures of ultraviolet radiation-induced erythema and related pro-inflammatory mediators,” authors Mahendra P. Kapoor and colleagues wrote. “Regular intake of as low as 540 mg of green tea catechins per day could be beneficial for the protection against ultraviolet radiation-induced erythema, wherein green tea catechin metabolites are bioavailable at the dermis and epidermis levels of the skin, and thus increase the minimal dose of radiation (MED) required to induce erythema.”

Dr Kapoor added that the study “suggests that green tea catechins can strengthen the skin’s tolerance to ultraviolet radiation-induced skin damage from radiation through the prevention of the ultraviolet radiation-induced perturbation of epidermal barrier functions.”

Study details: 12 weeks of green tea intake yields benefits

The meta-analysis included three randomized, double-blind, placebo-controlled trials and one non-double-blind, non-placebo-controlled study that examined potential protective effects of orally administered capsules containing green tea catechins against sunburn (clinically known as erythema) induced by solar-simulated UV radiation. Two additional studies that involved a single dose of topically administered catechins were separately analyzed.

Pooled analysis of data from three studies that evaluated erythema in skin exposed to UV radiation before and after 12 or more weeks of green tea catechin intake revealed a favorable effect in association with catechin intake. Both low and high doses of the green tea capsules were effective at decreasing low-dose UV radiation-induced erythema. It was also noted that a significant favorable effect was seen in the one study which assessed UV radiation-induced erythema after green tea intake for only six weeks, but as none of the other studies assessed this shorter duration of intake, further analysis was not performed.

When green tea catechins’ effects compared to a placebo were analyzed, pooling the data of two placebo-controlled trials confirmed their effectiveness against low-intensity UV radiation-induced erythema.

Pooling data from participants in the studies involving topical green tea catechins revealed significant benefit for green tea at higher UV radiation doses.

*Kapoor MP et al. Molecules. 2021 Jun 17;26(12):3702.