Zoe Diana Draelos, M.D.Why do some Vitamin C preparations turn orange on the skin?
Many of the state-of-the-art cosmeceuticals contain vitamin C, a potent antioxidant important in skin health. Vitamin C is a secondary antioxidant in the skin, able to donate an electron to vitamin E, which is the primary antioxidant. As part of the electron donation process, the vitamin C itself becomes oxidized. This process can be observed on a daily basis when cut fruit is left on the dinner table. Freshly cut peaches have a vivid orange/yellow color due to their high vitamin C content. However, left on the table for several hours at room temperature, the peaches will turn brown. This browning is due to oxidation of the vitamin C and the color change is due to a chemical reaction occurring as the electron is lost. Once the electron is lost, the vitamin C is no longer an active vitamin, meaning the vitamin C content of a fresh cut peach is much higher than the vitamin C content of a browned peach.
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Now consider the vitamin C serums for facial antiaging purposes. When in the vitamin C is in high concentration, the serum will have a yellowish color, but as it oxidizes, it will turn brown/orange. Cosmetic vitamin C preparations that have discolored should be discarded as they have already oxidized and cannot provide skin benefits. Vitamin C preparations can also discolor on the skin surface as they contact oxygen in the environment. This accounts for the orange color that may emerge on the skin in the morning after wearing a vitamin C preparation overnight. For this reason, vitamin C serums should be in light and oxygen impermeable packaging. It is also important that consumers not repackage or leave the serums open to the air for enhanced spoilage.
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