Green tea extracts fail to protect skin against UV
Three months of supplementation with encapsulated green tea extract (2700 mg per day) with vitamin C (100 mg per day) was not associated with any reductions in sub burning or reductions in any biomarkers of inflammation compared with placebo.
Previous research has suggested that exposure to sun for people with fair skin (phototype I/II) promotes oxidative stress and inflammation in the skin, and that antioxidants may attenuate skin burning. Previous data from studies using lycopene or superoxide dismutase, for example, have suggested beneficial effects of antioxidants on skin reddening.
However, the new study, performed by, found no benefits of three months of supplementation for reducing skin erythema (sun burn), leukocyte infiltration, or eicosanoid response to ultraviolet radiation. Scientists from the Universities of Manchester, Leeds, and Bradford report their findings in the American Journal of Clinical Nutrition.
The results disagree with an earlier study from the same scientists published in 2013 in the British Journal of Nutrition, which did find that green tea extracts may help protect against sunburn and the longer-term effects of UV damage.
The 2013 study was an open, uncontrolled study and the effects were modest, noted the researchers in the newest paper. Also, the dose used in the 2013 was half that used in the current study.
“It is important to acknowledge the limitations of open, uncontrolled studies, particularly the inability to allow for changes in outcome measures during the course of supplementation that are unrelated to consumption of the supplement,” wrote the authors in the AJCN. “There is also the possibility of a nonlinear dose-response effect, because higher concentrations of nutritional supplementation are sometimes reported to be less effective.
“Future studies might examine EGCG dose effect, discuss the impact on other chemokines, and explore the skin content of GTCs and their metabolites,” they concluded.
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi:10.3945/ajcn.115.107995
“A randomized controlled trial of green tea catechins in protection against ultraviolet radiation–induced cutaneous inflammation”
Authors: M.D. Farrar, A. Nicolaou, K.A. Clarke, et al.