Also known as: Vitamin C
Found in: Lotions, face washes, anti-aging products, skin-lightening serums and creams
Where it comes from: Since extracting enough vitamin C from natural sources, like citrus fruits, is expensive, L-asorbic acid is made in the laboratory. It's the chemical equivalent to vitamin C.
What it does: This antioxidant protects against environmental damage and reduces inflammation. It also stimulates the production of collagen, a protein that gives skin its smooth, firm appearance.
In higher doses (roughly a 10 percent concentration), it can lighten skin and fade dark spots. L-asorbic acid is harmless, but high doses may lead to skin irritation in some people. If exposed to air, products with the compound can turn brown over time. They're still safe to use, but they may not be as effective as they once were.
Expert source: Art Georgalas, a cosmetic chemist in Warwick, New York, and owner of Georgalas Endeavors, LLC
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