One of the most influential voices in cosmetic chemistry today, Stephen Alain Ko lives and breathes skin-care ingredients and their scientific idiosyncrasies—just take a peek at his blog, KindofStephen.com. One he’s particularly savvy with? Vitamin C. “It’s a game changer in skin care,” he says. “Outside of prescription topical ingredients, it’s one of the most impactful and well-studied.”
Ko loves vitamin C for its ability to protect skin from free-radical damage, including that from UV exposure, environmental pollutants, smoke, alcohol, and even some fried foods. “It’s backed by a large sum of research that shows it can improve sallowness and dark spots to brighten the skin, while also stimulating collagen production,” he explains. “These effects help minimize changes in the skin associated with aging, such as fine lines and sun damage.”
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Ko also shared three things you probably haven’t heard about the ingredient, but should know before buying or using it:
1. Modified versions of ascorbic acid are not more effective.
Ascorbic acid (aka L-ascorbic acid) is the pure form of the vitamin, but it’s very unstable and prone to oxidation—it’s sensitive to heat, light and oxygen, especially in the presence of water. This also means it has a shorter shelf life. To improve its stability, cosmetic chemists developed derivatives of ascorbic acid—ascorbyl palmitate and sodium ascorbyl phosphate are the two most common—and often use them in products instead of ascorbic acid. “However, this requires a modification of the chemical structure of the vitamin to make it more stable, and research proving this modified version is more effective is scant, if not inconclusive,” Ko says. “That’s why I prefer using vitamin C in its pure ascorbic acid form, despite its stability issues.”
2. Combining vitamin C with specific ingredients makes it work that much harder.
Studies show that skin-care products containing a blend of ascorbic acid, ferulic acid and vitamin E are best for protecting skin from UV rays. “This ingredient combination is based on research by Dr. Sheldon R. Pinnell, the founder of SkinCeuticals. It was patented and is commonly referred to as the Duke Antioxidant Patent,” he says. “In a group of experiments, Dr. Pinnell and a team of researchers found that the addition of 1 percent vitamin E to 15 percent vitamin C doubled the photoprotection offered compared to just vitamin C alone. Later, they found that the addition of ferulic acid to the combination doubled the level of photoprotection once over.”
3. Vitamin C can be combined with niacinamide in most cases.
According to Ko, one ingredient many experts have said shouldn’t be combined with vitamin C is niacinamide (vitamin B3). “The concern is that niacinamide converts into niacin when mixed with vitamin C, which can cause a flushing of the skin. However, the conversion of niacinamide to niacin takes time and heat, so it is more of a concern for product manufacturers, not consumers,” he says. “In my opinion, this was based on a misunderstanding of the research—the combination is actually fine for most people. Additionally, not everyone is sensitive to niacin flushing, which is often confused with redness caused from an irritation to the product.”
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