In recent years, inclusion of green tea in nutritional, anti-aging, and skin care products has been on the rise; mainly because of its rumored ability to reduce the impact of UV radiation on the human skin 1.
The initial move towards green tea supplementation arose from findings conducted on mice. The studies proved that the polyphenolic compounds found in green tea have anti-inflammatory and antibiotic properties, and they can repair and protect the mice skin from the damaging UV rays2. However, there was no empirical study that had proven the clinical significance of green tea relative to its ability to repair or protect the human skin from the damaging effects of UV rays.
A double blinded, placebo controlled study by a group of scientists from Stanford University concludes that Green Tea is clinically significant in repairing and protecting the human skin from photo-aging and damage.
Study Design and Methodology
The researchers selected 40 women with skin age 2-3 on the Glogau scale of photo-aging, Fitzpatrick skin type I-III or both 2. The 40 women were randomly placed into two groups of 20 each (the treatment and the placebo group) to facilitate a double blinded, placebo-controlled study to determine the role of combination regimen of topical and systemic application of green tea extract in the improvement of skin appearance and protection against damage caused by UV radiation. The two groups were subjected to differing treatment regimens:
All the subjects in the study were instructed to use the treatment regimen for eight weeks. They were not informed about the specific ingredients in the creams and oral supplements they were given. Before the study commenced, skin biopsies were taken and subjected to both histological and clinical grading to establish a variety of factors. The research group used a standardized scale based on a University of Arizona study for both histological and clinical grading 3.
35 of the 40 subjects completed the treatment regimen satisfactorily. The researchers obtained 4 millimeter punch biopsies of the subjects' skin at baseline and end of the study. The skin biopsies of both groups were compared at baseline and at the end of the 8 week treatment period.
When the results were compared on the established histological scale, the biopsies of the treatment group taken at the end of the study showed a clear and consistent improvement of up to 0.7 units. The placebo group did not exhibit any improvements on the same scale.
When the baseline and final observations were compared using the clinical scale, neither the treatment group nor the placebo group exhibited any significant improvements.
Application of topical creams, cleaner and sunscreen containing green tea extract as well as oral ingestion of green tea supplements is effective in increasing skin elasticity in a period of two months or less. This is broadly consistent with other studies which have shown that polyphenolic compounds from green tea are suitable for reversing the carcinogenic damage of UV radiation as well as reversing inflammation of the skin 4.
While such histological improvements are welcome and significant, no clinically significant observations were noted after the 8-weeks. This suggests it’s necessary to device a study which spans over a longer period to establish whether there are significant improvements to be gained from green tea extract supplementation and oral application.