Glutathione has multiple physiological effects. It inhibits melanin production by inhibiting tyrosinase activity, and oral GSH in humans reduces melanin production in the skin. However, glutathione in aqueous solution is extremely unstable and easily decomposes. In contrast, GSSG is not easily decomposed in aqueous solutions and is suitable for use in liquid form, so it is mostly used for external use.
A research team selected 30 healthy adult women between the ages of 30 and 50 to study the effects of topical oxidized glutathione on skin whitening and improving skin condition. The study design was a randomized, double-blind, matched, placebo-controlled clinical trial. Subjects applied GSSG 2% (weight/weight [w/w]) lotion to one side of the face and placebo lotion to the other side twice daily for 10 weeks. The study objectively measured changes in melanin index values, stratum corneum moisture content, smoothness, wrinkle formation and skin elasticity. Studies have also investigated skin whitening, wrinkle reduction and smoothness.
From the first few weeks after the start of the trial to the end of the study period, the melanin index of skin treated with GSSG was significantly lower than that of placebo (P<0.001 at 10 weeks). In addition, during the second half of the study, the moisture content of the stratum corneum in the GSSG-treated site was significantly increased, wrinkle formation was inhibited, and skin smoothness was improved. There were no apparent adverse effects from GSSG application. Studies have proven that topical GSSG is safe and effective in whitening skin and improving skin condition in healthy women.
▲Changes in melanin index value after GSSG treatment
Of course, there are also studies demonstrating that a combination of topical and oral glutathione may be superior to monotherapy.