Friday Aug 15, 2014 (foodconsumer.org) -- Sunlight or ultraviolet B (UVS) irradiation induces production of reactive oxygen species (ROS) in the skin, which in turn triggers expression of matrix metalloproteinases and collagen degradation.  Chronic exposure of the skin to UVB irradiation can histologically change the skin leading to the formation of wrinkles, abnormal pigmentation and loss of elasticity.

Korean scientists at Yonsei University in Seoul, Korea tested green tea extract in hairless mice that were exposed to UVB irradiation three times a week for 10 weeks. They found the dietary supplement reduced UVB irradiation-induced wrinkle formation and decreased the density of dermal collagen fiber.  Additionally, supplementation with green tea extract significantly increased the activity of antioxidant enzymes, which was decreased by UVB irradiation.  

Green tea extract dosage:  The doses of green tea extract were 100 mg/kg and 200 mg/kg.  Green tea extract at 10mg/kg did not render any significant protection.  Vitamin C at 100 mg/kg used as a control in the study was also found effective at reducing the skin damage induced by UV rays.

Green tea extract provides other benefits and has been used for weight loss and cancer treatment. (David Liu, PHD)

Lim JY, Kim OK, Lee J, Lee MJ, Kang N, Hwang JK.  Protective effect of the standardized green tea seed extract on UVB-induced skin photoaging in hairless mice. Nutr Res Pract. 2014 Aug;8(4):398-403.