Everything You Ever Wanted To Know About Vitamin C

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Nowadays, vitamin C is a very well-known skincare ingredient. Ask any beauty buff or skincare enthusiast, and it's likely they'll be able to recite the following...Vitamin C, when applied topically, brightens dull and sun-damaged skin and stimulates collagen production to ward off fine lines and wrinkles. It's also a powerful antioxidant, meaning it fights free radicals that could cause future signs of aging (which is why it's often a core ingredient in anti-pollution skincare regimens). But let's take a step back. What exactly are free radicals? It’s a term that’s thrown around a lot in the beauty industry, yet for many of us it's unclear how they affect our skin or why they're so feared. We spoke with celebrity esthetician and skincare expert Renée Rouleau, dermatologists Whitney Bowe and Lisa Pruett, and cosmetic chemist Ginger King—founder of product development firm Grace Kingdom Beauty—for more on the effective (if used correctly) ingredient.

Type of ingredient: Antioxidant

Main benefits: Brightening, alleviates hyperpigmentation, neutralizes free radicals.

Who should use it: In general, anyone struggling with sun-damaged skin or those looking to prevent dark spots in the future.

How often can I use it? Most dermatologists recommend using vitamin C once daily, but everybody's skin is different.

Works well with: Ferulic acid and vitamin E

Don’t use with: Retinol, copper peptides, Alpha Hydroxy Acids—all of which can destabilize Vitamin C, rendering it ineffective

What is Vitamin C?

According to Pruett, a dermatologist with U.S. Dermatology Partners, vitamin C is "the most common antioxidant applied topically for its anti-aging effects in the U.S.," as it has been found to neutralize free radicals. Free radicals such as reactive oxygen species (ROS)—found in everything from smog to cigarette smoke—damage the dermis of the skin and alter DNA, the moisture barrier, skin texture, color, and cell functioning.

The powerhouse ingredient does more than just protect against pollution, though. "Vitamin C has reached hero status in the world of skincare because of three proven benefits for the skin, all of which have been demonstrated in clinical trials: it acts as a powerful antioxidant, boosts collagen production, and brightens dark spots," says New York-based Bowe.

benefits of vitamin C
Alison Czinkota/Byrdie

Benefits of Vitamin C for Skin

• Promotes collagen production: Vitamin C is a potent antioxidant, helping to promote collagen production (studies have found that it has the potential to accelerate bone healing after fractures).

• Prevents premature aging: Lighter, more even skin looks fresher. Thanks to its ability to plump and smooth skin—and lighten sun damage—vitamin C usage can result is a naturally more youthful appearance.

• Lighten dark spots: Scientific studies have found that not only can vitamin C prevent future photo-damage, but—when applied topically—it can actually treat UV-induced damage.

• Neutralize free radicals: As an antioxidant, vitamin C helps to heal damaged skin cells.

• Firms skin: Hyaluronic acid has been touted for its abilities to speed recovery time among those who are injured; vitamin C just so happens to be a critical component to the synthesis of hyaluronic acid. Because it boosts collagen, the result is a naturally more firm skin surface.

• Reverses oxidative damage: To demonstrate the effects of ROS and oxidative stress to the naked eye—and to prove how vitamin C works to combat them—Rouleau devised a simple experiment involving an apple. She cut out a single slice and coated one end with a thin layer of Vitamin C&E Treatment ($70). The other she left completely untouched. Then she waited three hours. This is what happened…

How Does Vitamin C Work
Renée Rouleau

As you can plainly see, the side of the apple that was coated with the vitamin C serum didn't oxidize at all. "This shows how topical vitamin C can prevent oxidation and therefore slow down the visible appearance of aging," Rouleau says.

In the video above, skincare vlogger @gothamista used SkinCeuticals C E Ferulic ($166), which just so happens to be one of team Byrdie's all-time favorite serums. She starts out the experiment by applying a couple of drops to one half of an apple. After time goes by, we see that the other side of the apple is brown while the serum side is bright and fresh-looking. The serum had effectively protected the apple from oxidizing. 

She then applies a few drops of the C E Ferulic Serum to the browned half of the apple which, over time, visibly reverses the oxidation damage of the apple, taking it from brown and over-ripe to fresh and bright. That, our friends, is the perfect demonstration of the brightening, preventative, and rejuvenating effects of vitamin C.

Side Effects of Vitamin C

Vitamin C, although not known to be particularly irritating, is also not known for its complete lack of side effects. It won't give you a rash, most likely, but it could be a cause for redness or a slight increase in redness, at least at first.

Use a barrier booster or hydrating serum to help protect your skin against redness when you start your Vitamin C regimen.

If you experience severe itching or hives, however, wash your face and make a doctor's appointment—you might have an allergy.

How to Use Vitamin C

When shopping for a truly effective vitamin C product, the most important thing to consider is type, explains King: "The best kind is vitamin C Ester, commonly seen as Tetrahexyldecyl Ascorbate, or 3-O-Ethyl-L-Ascorbic Acid—both are my preferred choice, due to proven stability." While pure vitamin C degrades in water—rendering it ineffective—Tetradecyl Ascorbate and Ethyl Ascorbic Acid can be more readily absorbed into the skin. Packaging is also important. King recommends looking for vitamin C products packaged in amber glass containers, which won't let in light (and therefore destabilize the product).

Now for the best type of usage. Bowe recommends that patients apply vitamin C "after they cleanse and before they moisturize in the morning," and to slowly build up a tolerance over time. "If you don't experience any stinging, burning or sensitivity after two weeks of using it every morning, you can consider using a second application at night."

King advises not mixing vitamin C with retinol, copper peptides, and Alpha-Hydroxy Acids. "In general, you don't want to overburden skin with multiple actives that are known to give irritancy," she says. "Stable vitamin C has a narrow range of preferred pH (5-6)." Combining it with the wrong ingredients could lead to inefficiency.

Vitamin C does, however, get along just fine with some other ingredients, and works particularly well when used in conjunction with CoQ10. "In one study, use of both together in non-skin tissue worked better than each alone," says Pruett. "It can be applied to the skin daily and there are no major interactions with other topicals so it plays well as an addition to your current skincare routine."

The Best Products with Vitamin C

SkinCeuticals C E Ferulic
SkinCeuticals C E Ferulic $166

We could never forget the Skinceuticals serum. Although its star ingredient is vitamin C, it's also formulated with vitamin E and ferulic acid (and housed in an amber bottle, to better preserve efficacy). The former smoothes the skin, while the latter enhances the protective powers of the vitamin C. Ferulic acid also addresses dullness and loss of firmness, so you can be fighting aging both preemptively and retroactively.

True Botanicals Vitamin C Booster $90

True Botanicals' Vitamin C Booster is not only packaged in amber, it also comes in the form of a powder—ensuring it doesn't destabilize in water. Of course, since it's kind of a DIY product (the directions advise mixing the powder with your serum of choice), you'll need to pay close attention to what you mix it with.

truth serum vitamin c serum in an orange bottle with a white pump
Ole Henriksen Truth Serum $24

Ole Henriksen's Truth Serum is one of those products you've seen so many times, it's probably what you picture when you read the words "vitamin C serum." Henriksen's orange frosted-glass bottle with the white pump is nearly synonymous with the rise of skincare as a self-care practice. Not only is it that popular, it just works that well.

C-Firma Day Serum
Drunk Elephant C-Firma Vitamin C Day Serum $80

Another vitamin C serum whose popularity is so great it's near-synonymous with the category is this one from clean beauty brand Drunk Elephant. The founders of the brand believe that their line can be used by anyone, and complaints about this serum are fewer and further between than they are for most vitamin Cs. If you have super sensitive skin, start out with this one.

CEO vitamin C rich hydration cream in a tub
Sunday Riley C.E.O. Vitamin C Rich Hydration Cream $65

Just like we loved the oil and serum that preceded it, we absolutely love Sunday Riley's C.E.O. cream. It's rich and hydrating, which is perfect for the time of year when you need the biggest brightening kick: winter. But this is a year-round moisturizer; the Vitamin C helps get rid of and stave off any hyper-pigmentation issues the sun brings in summer, too.

lucent facial concentrate
Aesop Aesop Lucent Facial Concentrate $115

Vitamins C and B3 (niacinamide) work together in this hyper-conditioning serum from cult brand Aesop. Unlike many vitamin C products, it doesn't have that distinct vitamin C smell, and the flower oils it contains are far enough down in the ingredients list that it shouldn't pill when used under a silicone moisturizer or face product.

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