In vivo efficacy of a stabilized Vitamin C-based serum at pH 6 on some ageing facial signs of women of different ages and phototypes.

Abstract

Objective: To assess, clinically and instrumentally, the efficacy of a stabilized 12% Vitamin C (VC)-based serum (pH 6) on skin photoageing of women of various age and phototype.

Materials and methods: Eighty women, with Phototypes I to VI, of various age (45-70y) living in Mauritius, participated in an open, uncontrolled study. After a two-week period of washout, they applied the Vitamin C-based serum twice a day for 2 months onto their whole face as well as a hydrating cream every evening to ensure a comparable skin hydration level in all subjects. At set time intervals (D0, D immediate, D14, D28 and D56), a local dermatologist graded eight facial signs by visual or tactile assessments, using a 0-9 structured scale. At each time interval, the facial skin was imaged by standardized technique (Colorface™) and through echography (Dermascan™) to record its thickness and density. Skin elasticity was recorded by a the Cutometer® device under a controlled suctional stress. A questionnaire was filled out by all subjects recording their self-assessments of the serum's effects and several organoleptic properties.

Results: Compared with the baseline values (D0), the skin of all subjects showed progressive and significant changes in glow, tone evenness, radiance, firmness, softness and smoothness, associated with a reduction in fine lines. Deep wrinkles, only observed on 26 subjects, were found to be reduced. Self-assessments corresponded well with both clinical and instrumental results and indicated excellent skin tolerance. Ultrasound recordings exhibited significantly thicker and denser skin at D56.

Conclusion: If certain changes in some skin facial signs (skin tone and related items, firmness, sagging…) are linked to the high concentration of VC, a complementary impact of increased skin hydration remains possible due to the glycerol present in the serum and hydrating cream. These significant performance results in vivo showed that a very acidic medium (∼pH 3) is not a prerequisite to an efficient VC cosmetic formula, as has long been accepted in the cosmetics industry. Such a low pH can fragilize the skin equilibrium over time. As second originality, the studied formula seemed to fit all phototypes.