When it comes to glowing, radiant skin, a lot of my patients reach for the bottle. As in, that bottle of the latest skin serum, expensive moisturizer, or high-tech night cream.
Where does Vitamin C excel?
It provides an extra layer of protection against free radical damage
It boosts the protective effects of sunscreen
It helps prevent freckles and dark spots by running interference with melanin-producing cells and the enzymes that produce melanin
Where is the hype stronger than the science?
We just don't have strong evidence that topical vitamin C actually firms up collagen in those who consume a healthy diet
Topical vitamin C is not the best choice for erasing fine lines and wrinkles
Topical vitamin C isn't the best choice for erasing dark spots
Vitamin C Has Long Been Known To Be Critical For Healthy Skin
We've actually known for centuries about the importance of vitamin C for skin health. Centuries ago, sailors were at high risk for scurvy, a disease caused by a deficiency of vitamin C in their diet. Without enough vitamin C, sailors would develop a whole slew of problems, including bleeding gums and wounds that just wouldn't heal. That's because vitamin C is a critical component in the production and maintenance of collagen. That's one of the reasons that researchers have looked so closely at vitamin C as an anti-aging ingredient in skin care formulations.
Vitamin C: Before You Reach For a Skin Cream, Make Sure You're Getting Enough Vitamin C in Your Diet
Your skin is an amazing organ, and most of the time it functions beautifully. It protects you from the elements, from the cold and the heat, and from all of the different chemicals and objects that we brush up against all day long.
It is also the major line of defense against UV radiation.
In fact, your skin is under siege every minute of every day, from UV radiation, smoke, pollution, and other forces. These forces all act to increase the production of free radicals. Free radicals are molecules that contain an unpaired electron, and they're very dangerous to the lipids, proteins, and DNA in your skin. In fact, one of the major causes of skin cancer is the accumulation of DNA damage that results from the free radicals produced by UV radiation.
Your body, thankfully, has wonderful systems in place to fight these free radicals. These systems include certain enzymes in the skin, such as superoxide dismutase and glutathione peroxidase. These protective systems also include plenty of antioxidants, including vitamins C and E.
Although these antioxidants are constantly being used up, they're also constantly being replenished: the foods that you eat provide a consistent supply of these important chemicals. (That's why the antioxidants in your food are so critical to healthy skin.)
The antioxidants found naturally in certain foods make their way from your digestive system, to your blood supply, and from there to the tiny blood vessels that supply your skin. They then diffuse into the epidermis and dermis, where they protect your skin from free radicals. That's the "inside-out" approach to skin protection.
Research has also documented that an extra dose of antioxidants from your skin care products can also help replenish your skin's supply.
Hype Alert: Any Study of Topical Vitamin C and Its Effects On Collagen Needs To Look At Dietary Intake
Which brings us to one of the major unanswered questions with vitamin C in skin care. If you're getting enough vitamin C in your diet, does using it topically actually increase the vitamin C content any higher in your skin? Good question, and we still don't know for sure.
We do know that if you don't have enough vitamin C in your diet, then that extra dose from a topical application may help your skin. And this may be where all the hype about vitamin C originated.
In one study, topical vitamin C was used on the forearm, and then levels of a marker of collagen production were measured via skin biopsies. While the topical vitamin C did seem to increase the production of skin collagen, there was a major caveat. This increase in activity was much more apparent in women with the lowest levels of vitamin C in their diet.
That's why the first step in skin care starts from the inside: you need to ensure a diet that's naturally rich in antioxidants. That's the foundation of glowing, radiant skin.
Vitamin C products in your skin care products may add a little extra insurance
The Science of Skin Care: What Do the Studies Show? Vitamin C and other antioxidants provide an extra layer of protection against free radical damage
Free radicals are molecules that contain an unpaired electron, and they're dangerous. I think of them as ping ponging around your epidermis and dermis, and leaving a lot of damage in their wake. They directly harm your skin's proteins, lipids, and DNA. They also activate harmful enzymes called MMPs: matrix metalloproteinases. These MMPs include collagenase and elastase, and I call these "scissor enzymes". These scissor enzymes snip away at the collagen and elastic fibers that support your skin. Without strong intact collagen and elastic fibers, your skin starts to lose its strength and elasticity, ultimately leading to wrinkling and sagging of skin.
Topical vitamin C can block this harmful sequence of events. In one study of healthy adults, a mixture of vitamin C and other antioxidants were applied to the skin after exposure to ozone. This topical mixture helped to prevent the activation of these scissor enzymes, thus protecting the skin.
In another study, volunteers used a skin cream containing vitamin C that was encapsulated in liposomes. They were then exposed to UV radiation. The researchers found that the use of this skin cream resulted in increased vitamin C levels in the skin's epidermis and dermis, AND resulted in increased protection against UV radiation.
Vitamin C boosts the protective effects of sunscreen
Studies have found that using sunscreen with antioxidants provides greater protection against UV-induced skin damage than just using sunscreen alone. In one study, using a sunscreen that contained vitamins C and E provided greater protection against photodamage than just sunscreen alone. These results held true for both UVA and UVB damage. (UVA and UVB are the major types of UV radiation that damage the skin.) Remember, even the best sunscreens allow some penetration of UV radiation, and antioxidants do a great job of battling UV-induced skin damage.
Vitamin C helps prevent dark spots by interfering with the production of melanin
In one animal study, a topical formulation containing both vitamin C and vitamin E was used on the skin, and then followed by UV radiation exposure. Usually, UV radiation leads to increased activity of melanocytes, which are the melanin-producing cells in the skin. This leads to tanning, and eventually to permanent freckles and "sun damage spots" called solar lentigos. In this study, however, this particular topical formulation was able to reduce the activity of the melanocytes.
Laboratory studies have also looked at this process. Studies have looked specifically at human melanocytes, and whether treating these cells with vitamin C derivatives could help reduce their production of melanin. These studies have confirmed that this works: in one experiment, melanocytes reduced their production of melanin by 50% following treatment with a vitamin C derivative.
A Few Caveats: Where The Hype Is Stronger Than The Science
Topical vitamin C is not the best choice for erasing fine lines and wrinkles
We just don't have strong evidence that topical vitamin C actually firms up collagen.
The studies right now indicate that using vitamin C topically can certainly help protect collagen, especially if you're not getting enough in your diet. That extra dose from your skin cream can increase levels of vitamin C in your epidermis and dermis, and that can protect your collagen. Beyond that, though, we just don't have good evidence that topical vitamin C will REPAIR collagen damage.
To actually repair collagen damage, dermatologists are far more likely to recommend ingredients that have much more research supporting them. Derivatives of vitamin A, including retinol and prescription-strength tretinoin, have much more supportive evidence when it comes to effective collagen remodeling.
Topical vitamin C isn't the best choice for erasing dark spots
The research has found that they can certainly prevent the development of dark spots following UV exposure, but the research showing that they can lighten dark spots is much less robust. While they may help somewhat, most dermatologists will advise stronger treatments if you're trying to lighten dark spots. These include prescription strength vitamin A derivatives such as tretinoin, or bleaching creams that contain safe concentrations of hydroquinone.
Choosing a Product
If you'd like that extra layer of protection against free radical skin damage, or would like a protect that helps reduce the activity of skin melanocytes, then you may be reaching for a skin care product that contains vitamin C. Before you do, though, make sure you choose the right product.
Judge a Product By Its Package
Vitamin C is very prone to oxidation. It's a strong antioxidant, because it donates an extra electron to neutralize free radicals. However, that also means that it's prone to oxidation itself. In the presence of light, heat, and even oxygen, the vitamin C molecule can start to destabilize. That means it loses its effectiveness. Some researchers are even concerned that an unstable vitamin C molecule can actually create MORE skin damage.
That's why the proper packaging is so important. You want to make sure the vitamin C product is protected from light, heat, and oxygen. Some of products come in an opaque glass bottles with a stopper, which helps address some of these issues.
The Proper Formulation Is Critical
Just because it contains vitamin C, doesn't mean that it will be effective. For vitamin C especially, the proper formulation is critical. Vitamin C is a water-soluble molecule, and your skin barrier is meant to repel water. In some cases, though, vitamin C is able to penetrate the skin barrier effectively. Studies have demonstrated some penetration at the right pH (less than 4). The concentration matters also: the optimal concentration for absorption, efficacy, and tolerability is thought to be between 10% and 20%. What that means is that at this level you'll have absorption (penetration through the skin barrier), efficacy (effective results), and tolerability (not too much irritation).
There are also different forms of vitamin C. While ascorbic acid can penetrate the skin barrier, it's not the most stable molecule, so researchers have studied other forms of it. [More on that in a moment.]
Finally, although vitamin C is a potent antioxidant, it's only one of the major players. Research has found that vitamin C functions much better in the presence of vitamin E. The combination functions even better when combined with ferulic acid. Researchers are looking at other combinations of antioxidants, so keep an eye out for advances in this area.
Choosing An Effective Formulation: Research Into Derivative Molecules
When formulating an effective topical vitamin C product, cosmetic chemists have to deal with several major issues relating to the product's effectiveness. With a vitamin C product, you need to make sure it's able to handle these issues:
It needs to penetrate the skin barrier
The molecule has to be stable, meaning it's able to resist oxidation
The molecule must either be in the form of ascorbic acid, or in a form that the body can covert to ascorbic acid
While chemists have created other formulations, there are potential issues with each one:
You can add a phosphate group to ascorbic acid to help stabilize the molecule, but that seems to interfere with its absorption through the skin
You can use a glucoside form of the molecule because it's stable and it penetrates the skin, but it's unclear as to how effectively the body is able to convert that molecule
You can use a palmitate version, because that's lipid soluble, which translates to increased uptake through the skin and animals, but there are still a few questions about this formulation. Is it truly stable, and is the body able to convert it?
Liposomes are another formulation, and due to the addition of lipids, they may be better able to penetrate through the lipid skin barrier. This is one formulation to keep an eye on.
Designing a Skin Care Regimen
Should you add vitamin C to your skin care regimen? If you'd like an extra layer of protection against UV-induced skin damage, or you'd like to limit the formation of dark spots, then a vitamin C product may be a good addition.
However, you do need to be aware that some of the hype about vitamin C is just that: hype.
What does that mean for you? It means that a topical vitamin C product isn't likely to be your dermatologist's first choice to erase fine lines and wrinkles, firm up collagen, or erase dark spots. For these issues, you'd need to use your vitamin C product in conjunction with other products.
The foundation of a skin care regimen is:
Cleansers and moisturizers suited to your skin type
A diet naturally rich in antioxidants and other powerful substances
For anti-aging skin care regimens:
Your dermatologist will often recommend a vitamin A derivative used at bedtime
If you're using a vitamin C product, the most effective ones are formulated in combination with other antioxidants
The Bottom Line
As a dermatologist, one of my major guiding principles is this: Your skin care regimen should always be customized to YOUR skin type and YOUR skin care concerns.
If you'd like that extra layer of protection against free radical skin damage, or would like a product that helps reduce the activity of skin melanocytes, then you may be reaching for a skin care product that contains vitamin C.
Before you do, though, make sure you choose the right formulation in the right package. Speak to your dermatologist about their recommendations.
Dr. Rajani Katta is the author of Glow: The Dermatologist's Guide to a Whole Foods Younger Skin Diet. To receive future updates on preventive dermatology and the role of diet, sign up here.