Main Component in Green Tea Protects against UV-radiation
By Evelin Maza
Green tea consumption has its origins in ancient China, where it was believed to affect “the five vital organs”. Nowadays, its health benefits have been scientifically proven: helps fight cancer, boosts brain function, improves celiac disease, etc. (1, 2).
Tea is rich in polyphenols, and green tea is actually 30% polyphenols. Most of this is made up by epigallocatechin-3-gallate (EGCG), one of the most powerful compounds in green tea.
Hence, in 2006, Chinese scientists conducted a study to examine the protective and reparative qualities of EGCG against ultraviolet radiation (UVR).
The experiment consisted in comparing the state of skin cells pretreated with EGCG at varying concentrations to the state of a control group of skin cells. First, these two groups of HaCaT cells, which are similar to human keratinocytes or epidermal cells, were placed in Petri dishes and exposed to ultraviolet B (UVB) irradiation. Then, they were allowed to multiply for 24 hours. Finally, certain elements were measured, such as cell growth and the production of nitric oxide (NO).
The harmful effects of too much sun
Nitric oxide (NO) is synthesized by nitric oxide synthase, which has a form that can be triggered into action by exposure to UVB radiation. The researchers state that, “NO has been implicated in the pathogenesis of various inflammatory diseases, including sunburn and pigmentation induced by ultraviolet irradiation.” NO has also been linked to many other ailments, including heart disease (3).
The analysis performed after 24 hours yielded interesting results. UVB-exposure decreased the amount of cell growth. However, increased cell growth was observed in the groups pretreated with EGCG. Also, the amount of NO produced was much higher in the cells after their exposure to UVB. Yet, EGCG lowered these levels of nitric oxide. The higher the concentration of EGCG, the lower the generation of NO.
Possible protection against the depleting ozone layer
“UVB irradiation can trigger different signals and effects on skin cells, causing photo-oxidative damage resulting in numerous pathologies, including dermatitis, skin photo aging and skin cancer,” added the scientists.
Thankfully, this study has shown that the EGCG found in green tea may provide protection against the harmful effects of UV radiation. The authors stated that “EGCG is a biochemically active compound with known anti-inflammatory, anticarcinogenic and free radical-scavenging properties.” And the findings of their study show that green tea and its components can be an effective treatment against sunburn.
“Green tea polyphenol epigallocatechin-3-gallate inhibits the expression of nitric oxide synthase and generation of nitric oxide induced by ultraviolet B in HaCaT cells”
Authors: Song Xiu-zu et al.
Source: Chinese Medical Journal
Volume 119, Number 4, Pages 282-287.
Evelin Mercedes Maza Guia is a physician from the University of Oriente in Anzoátegui, Venezuela. After completing her primary and secondary education in the United States, she moved back to her native country to pursue higher learning. After 7 and a half years of medical training, Evelin just received her “Médico Cirujano” degree, which is the Venezuelan equivalent to a general physician. Currently, she is also involved with many blogs about medicine and general well-being as a translator and content writer.