The clinical effect of glutathione on skin color and other related skin conditions: A systematic review

Summary Background Glutathione is one of agents which is commonly used to lighten skin color in Asia as a dietary supplement. Previous studies suggest its potential effect of glutathione on skin color. However, the clinical efficacy of glutathione in oral form is still questionable due to its limited absorption and bioavailability. Aim To determine the clinical effects of glutathione on skin color and related skin conditions. Patients/Methods A systematic review was conducted using PubMed, CINAHL, Scopus, EMBASE and Cochrane library were searched from inceptions to October 2017. All clinical studies evaluating the effect of glutathione on any skin effects in healthy volunteer were included. Results A total of four studies were included. Three studies were RCTs with placebo control, while one was a single‐arm trial. One study used topical form, while others used oral form of glutathione with 250 to 500 mg/day. We found that both oral glutathione with the dosage of 500 mg/day and topical 2.0% oxidized glutathione could brighten skin color in sun‐exposed area measured by skin melanin index. No significant differences in the reduction in skin melanin index were observed in sun‐protected area for any products. In addition, glutathione also has a trend to improve skin wrinkle, skin elasticity, and UV spots. Some adverse events but nonserious were reported. Conclusions Current evidence of the skin whitening effect of glutathione is still inconclusive due to the quality of included studies and inconsistent findings. However, there is a trend that glutathione might brighten skin color at skin‐exposed area.