Green tea extracts are being promoted as one of the greatest antioxidants due to the high content of polyphenols. The most well-known and researched polyphenols in green tea is epigallocatechin. It has shown positive results in studies measuring antioxidant effects for chronic diseases; skin conditions, and also is effective for weight loss.
Previous studies have shown that green tea is effective at reducing the damage to skin caused by UVA and UVB light. Most studies have been performed in animals, but the evidence is convincing. Today there are many commercially available skin care products with green tea or green tea polyphenols listed in the ingredients.
A study out of Emory University's Department of Dermatology tested the effects of oral and topical green tea on the clinical and cellular changes of facial skin due to photo aging (sun damage). The double blind placebo controlled trial enrolled 40 women with moderate photo aging. They were randomized to receive either a topical cream of 10% green tea extract applied daily and 300 mg/day of oral green tea supplementation or placebo. The duration of the study was 8 weeks.
Outcome measures included clinical appearance of the skin including any changes from baseline to completion of the study. The researchers also performed biopsies of the skin and assessed for any cellular or histological changes from the treatment compared to baseline and placebo.
The study found that there were no significant differences between the two groups in terms of clinical appearance. However, histological analysis revealed a significant change in elasticity in the treatment group. Biopsy showed an increase in elastic content of the cells in women treated with topical and oral green tea compared to baseline and the placebo group.
Green tea has shown in previous studies, namely animal studies, that it is protective against the damage caused by the sun. In this study, clinical evidence was absent, but measurable histological change was found due to the topical and oral green tea. Perhaps the dosage was too low, or the duration of the study was too brief. A larger long-term trial is needed to assess for clinical changes.
Posted by Kristopher Foster on March 15, 2006 03:18 PM
