CLEVELAND, OHIO. Animal experiments have shown that extracts from green tea are highly effective in protecting against the damaging effects of ultraviolet light. Researchers at the Case Western Reserve University now report that topically applied green tea extracts also are remarkably effective in protecting humans. Six volunteers were exposed to simulated solar radiation or pure UVA radiation 30 minutes after having had a solution of green tea extract applied to a 5 cm by 5 cm area on the back. The radiation duration was twice that previously established as being required to cause significant redness of the skin. The extent of redness (sunburn, erythema) was measured on protected and unprotected skin 24, 48 and 72 hours after the solar radiation exposure. Excellent protection was observed with a 2.5 per cent solution of extract (in alcohol and water) and complete protection against sunburn was evident with a 10 per cent solution. The number of sunburn cells created by the irradiation was reduced by 66 per cent in the extract-protected skin areas and DNA damage (a precursor to skin cancer) was cut in half.
Immune system function is known to be negatively affected by exposure to sunlight. It is believed that this, at least in part, is due to the destruction of Langerhans cells in the skin. Green tea extracts were also found to be quite effective in preventing this effect. Solar radiation destroyed 85 per cent of pre-radiation cells in unprotected skin, but only 36 per cent in skin protected with green tea extract. It was also found to protect against damaging UVA radiation. The researchers point out that the extract acts in a manner quite different from that of sunscreens. They conclude that green tea extracts may prove to be a valuable new alternative for protection from UV radiation. NOTE: This study was partially funded by Estee Lauder, a cosmetic manufacturer.
Elmets, Craig A., et al. Cutaneous photoprotection from ultraviolet injury by green tea polyphenols. Journal of the American Academy of Dermatology, Vol. 44, March 2001, pp. 425-32 [40 references]