Cosmetics formulations containing vitamin C and the instability challenge

Vitamin C (ascorbic acid) is widely used in skin care products, yet it is a challenging compound due to its physical and chemical instability. Several strategies have been applied to improve the stability of vitamin C, such as the addition of other antioxidants in the system (e.g., Vitamin E, ferulic acid, and sodium metabisulfite). In addition, clay minerals have been used in cosmetic preparations due to their high ion-exchange capacity, thermal stability, softness, the small size of their particles, and their attractive adsorptive properties. In this study, we proposed the association of kaolin clay and well-known antioxidants and chelators to improve the stability of vitamin C. Although the kaolin clay alone did not improve the stability of the vitamin C, the clay mineral in association with certain chelators and/or antioxidants could improve the stability of formulations containing vitamin C.