The popular antioxidant may be even more powerful in its powder form. Here's what you need to know before adding it to your routine.
The benefits of vitamin C for skin have turned the ingredient into a cosmetic darling—and deservedly so. It brightens the face, evens out skin tone, limits UV damage, and increases collagen production. (Related: The Best Anti-Aging Tips for Better Skin)
But there's one downside: The star antioxidant is notoriously unstable and thus has a limited shelf life.
"Vitamin C is inherently a biologically unstable molecule that oxidizes upon exposure to air, light, and heat," explains Julia Tzu, M.D., a New York–based dermatologist and founder of Wall Street Dermatology. So when serums or lotions are not stored in cool, dark, and dry conditions, that can speed up oxidation, causing the "degradation of the molecule," she says. And when the vitamin oxidizes, there's no benefit to the skin.
Enter vitamin C powder, which is exactly what it sounds like: a powdered version of vitamin C that cosmetics makers claim can be added to any moisturizer and dissolves to have the same effects, without the instability.
Powdered versions of the miracle ingredient solve a clear problem when it comes to vitamin C—it's difficult to create serums or creams that don't come into contact with heat or light, making the effectiveness of these products unpredictable, says Ron Robinson, a cosmetic chemist and founder of BeautyStat in New York. When the antioxidant is stored as a powder, it's more stable and less likely to degrade with light.
But the other big reason for the popularity of powdered vitamin C—which you mix at home into your existing skin-care products—is the overall hype around DIY beauty and creating a customized skin-care routine by combining various ingredients, Robinson says. "Companies are capitalizing on the do-it-yourself trend," he says. (Another big anti-aging skin trend right now? Copper.)
Derms agree that they may actually be on to something, but that consumers should proceed with caution: It's not as simple as ordering the first vitamin C powder you can find online. "Powdered vitamin C must be mixed in the right vehicle in order to be absorbed and then released into the skin," says Vivian Bucay, M.D., a San Antonio–based dermatologist. So mixing it in the right serums and proportions is key.
Part of this is about getting the right pH levels, which can be tricky when going the DIY route, Dr. Bucay says. "The pH of the vitamin C needs to be acidic (around 3.0) to absorb, which can cause some irritation when it comes into contact with skin," she says. Another word of caution: "The problem when someone prepares their own vitamin C product at home is that the vitamin C can crystallize on the skin before it ever penetrates for any beneficial effects."
Most derms advise against simply buying a box of the ingestible kind of ascorbic acid powder to use on your face. Instead, look for powders that can be used daily when blended with a lotion or serum that has the needed water content to help the vitamin absorb into the skin. Both the Vitabrid C¹² Face Brightening Powder ($60; barneys.com) and Philosophy's Turbo Booster C Powder ($39; sephora.com) can be mixed into a serum, moisturizer, or even sunscreen for a last-minute dose of vitamin C. Mary Kay's TimeWise Vitamin C Activating Squares ($24; marykay.com) make it simple to tote the powder around and need to be dissolved in water before being added to serum. Another important detail to note: Make sure the powders use the most natural version of the vitamin, the water-soluble L-ascorbic acid, which is less stable but more powerful than other synthetic versions including sodium ascorbate and ascorbyl palmitatem, Dr. Bucay says.
This isn't to say you should abandon your vitamin C–packed lotions and serums. After all, some studies show that vitamin C works best when combined with other antioxidants such as vitamin E or ferulic acid, which is only available in a serum. You should, however, beware of packaging and storage (or look for serums with newer forms of vitamin C that are oil-soluble and more stable). If you notice your vitamin C serum has oxidized and changed to a yellowish color, it's time to replace it—and consider a powdered version—to reap those glowing skin benefits.