What is L-ascorbic Acid?
Most people know vitamin C for its benefits when fighting the common cold or to treat scurvy. But vitamin C also plays a significant role in maintaining the healthy functioning of the skin. L-ascorbic acid is one of the two forms of vitamin C found in nature and is the most biologically active, meaning it is the most beneficial. L-ascorbic acid’s potency makes it the preferred form of vitamin C for most dermatological and skincare products. L-ascorbic acid’s full name may look a little daunting, but it just refers to a specific structure of vitamin C. Ascorbic acid is the name of vitamin C in the body and the “ L” in L-ascorbic acid refers to the way the molecule rotates to light.
L-ascorbic acid is the most abundant antioxidant in the body, but humans cannot produce it on their own unlike other mammals. Instead, we extract vitamin C through our diet or supplementation. Vitamin C is involved in many processes within our bodies, so the vitamin C we absorb gets distributed to all cells. However, the skin is often the last organ to receive vitamin C and does not receive it at the concentrations required to affect the skin in any significant way.
L-ascorbic acid is found in fruits and vegetables such as oranges, broccoli, leafy greens, grapefruit and peppers, they are a great source of dietary vitamin C. L-ascorbic acid is also found in kakadu plum and hibiscus, which are often used in clean vitamin C beauty products. Unfortunately, the amount of vitamin C in these sources is impacted by heating and its freshness. This is partly due to the breakdown of L-ascorbic acid that occurs when it is exposed to air, high temperatures and water. Most balanced diets will provide the body with enough vitamin C to support health.
However, naturally occurring sources aren’t stable enough or contain enough vitamin C to be used in skincare and improve the skin’s appearance. This is why L-ascorbic acid used in products is often synthetically sourced.
Applying vitamin C to the skin in serum, powder or oil form may help the skin receive the benefits of vitamin C. This is why topical vitamin C treatments are used by dermatologists to help improve the appearance of textured skin, pigmentation, acne and firmness.
the good: Helps to maintain skin barrier integrity, fights pigmentation, may be involved in inflammation processes in the skin, is involved in collagen production, and protects against sun damage.
the not so good: Highly unstable molecule that makes formulating difficult. This is why it is important to know what to look for when purchasing a vitamin C product.
Who is it for? All skin types. People with sensitive skin types should use a lower concentration of vitamin C and reduce the frequency of use.
Synergetic ingredients: Vitamin E and ferulic acid.
Keep an eye on: The source of vitamin C, the concentration and type of vitamin C product. Product types include gels, serums, and powders.
What Are the Benefits of L-ascorbic Acid?
L-ascorbic acid is a powerhouse ingredient that can help improve the appearance of the skin in multiple ways, making it an ideal product to bring into any skincare regime. Studies discussed in the Journal of Clinical and Aesthetic Dermatology have outlined the benefits of topical vitamin C treatments. Their research found evidence that topical vitamin C can help diminish the visibility of pigmentation, is involved in the collagen production process, may be involved in inflammation, reduce the sun’s effects on the skin, and maintain skin barrier integrity.
Environmental factors such as radiation from the sun, UVA and UVB, pollution, smoking, and diet can put the skin in a state of oxidative stress. Oxidative stress produces an imbalance in the levels of molecules called free radicals. This imbalance may lead to damage of cells and tissues within the body. Free radicals, also called reactive oxygen species or ROS, are a natural by-product of the body’s chemical processes. Think of them as your body’s waste. Free radicals can accumulate and create an imbalance. This imbalance has been studied for its links with many diseases and its role in the aging process. As an antioxidant, vitamin C is thought to reduce the effects of oxidative stress by neutralizing the free radical molecules and rebalancing their levels in the body.
Vitamin C and sun damage
When skin is exposed to UV light, it can produce free radicals as part of a process called oxidative stress. Free radicals are involved in a cascade of events that may reduce the amount of collagen the body produces, increase cellular damage, and may cause harm to the DNA within the cell. The effects of free radicals on the skin result in the appearance of deep wrinkles, pigmentation and loss of elasticity. These changes also tend to be associated with the natural decrease in collagen production and sun damage as we age.
As an antioxidant, vitamin C neutralizes the free radicals formed by exposure to the sun, giving vitamin C protective and restorative qualities against sun damage. Sunscreen remains the most effective way of reducing the effects of sun exposure. Still, studies have shown that vitamin C can enhance the protective abilities of sunscreens and help fight some of the visible pigmentation associated with sun damage.
Evidence from several studies displayed the protective properties of vitamin C against the sun’s harmful effects. These studies suggest that vitamin C and another antioxidant, vitamin E, heighten the protective abilities against the sun in sunscreen formulations. Dermatologists might recommend using a vitamin C serum containing vitamin E before a sunscreen to harness vitamin C’s ability to neutralize or rebalance the free radicals in the skin.
Vitamin C also helps to replenish vitamin E levels in the skin. Vitamin E, an antioxidant like vitamin C, has been studied for its involvement in immune function, maintaining skin health and its abilities in supporting the skin to protect itself from UV damage.
As we age, collagen production decreases. From age 20, the amount of collagen produced reduces by 1% per year. As a molecule, L-ascorbic acid has been studied for its role in pathways that produce collagen in the body. Collagen forms crosslinked fibers in the deeper layers of the skin which creates a net-like structure. It is thought that collagen may provide the skin with structure, firmness or elasticity.
Vitamin C acts as a cofactor or a helper molecule in the body’s natural collagen forming process. Studies have looked at L-ascorbic acid’s ability to crosslink and stabilize collagen fibers. Vitamin C has also been investigated for its involvement in the production of a molecule called procollagen mRNA. This molecule signals the production of collagen and is responsible for signaling to the cell that collagen is needed. While several studies support vitamin C’s involvement in the processes that produce collagen, research is ongoing as to whether skincare products containing vitamin C have significant effects in improving visible firmness and elasticity of the skin.
As the skin is the last organ to receive dietary vitamin C, topical L-ascorbic acid products such as powders and serums may be beneficial to improve the appearance of the skin. A study of vitamin C in skincare identified that topical L-ascorbic acid products increased L-ascorbic acid levels in the skin. The study also found that vitamin C products could improve the appearance of the skin at any age.
Pigmentation and L-ascorbic acid
Pigmentation occurs on the surface of the skin for a multitude of internal and external reasons. These can range from pregnancy or melasma, hormonal imbalance and sun damage to genetic predispositions, injury or inflammation. Melanin is the molecule responsible for giving skin color or pigment, and the uneven production of melanin results in pigmentation areas on the surface. Vitamin C works to reduce the visibility of pigmentation through inhibition of the enzyme responsible for producing melanin in the skin. By inhibiting the irregular production of melanin, vitamin C, at the right concentration and pH, can help minimize pigmentation’s appearance. Dermatologists might recommend concentrated vitamin C products alongside retinol and laser for pigmentation. Using vitamin C to reduce the appearance of pigmentation can take time and depend on the product’s strength and frequency of use. It is crucial to use sunscreen alongside vitamin C products to avoid further pigmentation from the sun.
Inflammation in the skin is common but some people experience it on a daily basis. Conditions such as acne, psoriasis, rosacea and eczema may cause the skin to be chronically inflamed.
Vitamin C is thought to inhibit a molecule that activates pro-inflammatory cytokines. Cytokines are involved in immunity and help produce the inflammation reaction in the body to heal – think of healthy wound healing. In conditions where the skin is chronically inflamed, the cytokines react inappropriately, often working in overdrive. Currently, topical vitamin C products are being examined for how it is involved in inflammation, wound healing and post-inflammatory linked pigmentation.
Skin barrier integrity
The skin barrier includes the outermost layers of the skin, and is essential for maintaining a healthy, clear complexion. It is responsible for protecting the skin’s deeper layers from damage, allergens, bacteria and moisture loss. When issues with the skin barrier occur, it may suggest conditions such as atopic dermatitis or eczema.
Vitamin C has been used in combination with other skincare ingredients and dermatological therapies to treat conditions that affect the skin barrier. Vitamin C is thought to maintain the skin barrier by enhancing the ability of keratinocyte. Keratinocytes are a type of skin cell that produces keratin. Vitamin C helps to specialize the function of the keratinocyte.
What should you consider when choosing a vitamin C product?
Stability of your vitamin C product
L-ascorbic acid is a highly unstable molecule. It requires a water-based environment, a low pH and antioxidants to increase its ability to deeply penetrate the skin. Those conditions are important for creating a stable and active vitamin C product. It is essential to understand why L-ascorbic acid requires these conditions when choosing a vitamin C product in order to find one that is effective and long lasting.
L-ascorbic acid has a reduced ability to penetrate the skin at its natural pH which is a result of its molecule structure. L-ascorbic acid is a charged molecule and is hydrophilic. These two characteristics mean that L-ascorbic acid will readily bind to water molecules, making it hard for the molecule to pass through the skin’s hydrophobic layers.
Reducing the pH of a product to less than 3.5 or less makes it more acidic, allowing for L-ascorbic acid to penetrate deeper and be stable for longer. However, reducing the pH of the product may lead to sensitization of the skin, as the natural pH of the skin is around. It is important to know the concentration of the product (more on that below).
To create a more stable product that lasts longer, some formulations use different forms of vitamin C. This includes magnesium ascorbyl phosphate or ascorbyl-6-palmitate, which are more stable at a neutral pH. However, a study conducted by Duke University Medical Center found that these two substitutes did not increase the natural vitamin C levels in the skin.
Some formulations include other antioxidants to help stabilize the L-ascorbic acid. Studies have suggested that incorporating ferulic acid and vitamin E can increase the stability and improve the product’s ability to penetrate deeply into the skin. A study published in the Journal for Investigative Dermatology found that ferulic acid stabilized the formulation and increased the protective capabilities of vitamin C to the sun’s effects.
In poorly designed products or formulations, the L-ascorbic acid can destabilize in the bottle, often leaving the product with a yellow hue. Oxidation is the process that causes this discoloration. In poorly designed formulations, the oxidation can also occur on the skin’s surface, leaving the skin with a buildup of free radicals and acidic by-products or waste. This can affect the health of the skin mantle barrier, interact with other products and hasten the aging process.
L-ascorbic acid will only stay active in skincare products for a short period once opened. Even well-designed products will experience this, as exposure to the air will oxidize the L-ascorbic acid. To increase a product’s longevity, look for powder formulations, products in vial form, or small product sizes. Look for products formulated with antioxidants such as ferulic acid.
Concentration is another critical element when considering which L-ascorbic acid products would best suit your needs. Some brands advertise a high level of vitamin C in their product, such as 100% L-ascorbic acid. While it may seem appealing to have concentrated products, formulas with more than 20% L-ascorbic acid can irritate the skin. Most dermatological studies have found that a range between 8-20% produces the best results with limited irritation.
A study conducted by Duke University Medical Center found that the concentrations of L-ascorbic acid above 20% do not have increased skin benefits.3 The study determined that conversely, higher levels can negatively impact the skin’s condition. Sensitive skin types should use vitamin C products in the lower part of the range.
Synthetic or plant-based vitamin C
Occasionally brands won’t advertise the strength of the vitamin C content in the product but instead focus on the source. This lack of information regarding concentration tends to occur with formulations utilizing kakadu plum, hibiscus or plant-based vitamin C sources. The issue with plant-based sources of vitamin C is that they tend to be low in concentration and are generally unstable. The strength of L-ascorbic acid in kakadu plum is about 2% which means it cannot affect the skin in any significant way. The low concentration of L-ascorbic acid in plant-based sources and the instability of most natural sources is why most effective vitamin C products use a synthetic form of L-ascorbic acid in their formulations, including most clean beauty brands.
Vitamin C products
Many product types can deliver vitamin C to the skin, including gels, serums and powders. L-ascorbic acid is a water-soluble molecule that requires a low pH and the inclusion of stabilizers and antioxidants, which means that most L-ascorbic acid formulations will be in a water base or dried form. Some are formulated in an oil base.
L-ascorbic acid delivered in gel or serums is absorbed quickly without adding extra moisturizing products which makes them suitable for oily or acne prone skin. They also work well with an established skincare routine, as they avoid disrupting a working regime. Powder forms of L-ascorbic acid prevent the need for many stabilizers. They reduce the risk of decreased effectiveness through exposure to the sun and air as the product becomes active only when mixed with water.
Other types of vitamin C
The type of vitamin C often varies between formulations. As a vitamin C source, L-ascorbic acid is the most well-researched source and the source that has shown the most benefits to the body. Other forms of synthetic vitamin C used in skincare are mineral ascorbates, calcium ascorbate, magnesium ascorbate, ascorbyl palmitate or tetrahexyldecyl ascorbate. The type of vitamin C and the type of product can have a significant effect on the efficacy of the product.
Studies have indicated that tetrahexyldecyl ascorbate might equal L-ascorbic acid in terms of effectiveness. Tetrahexyldecyl ascorbate is an oil-soluble form of vitamin C that works alongside other products such as retinol. In a review conducted by the Cosmetic Ingredient Review, evidence indicated that tetrahexyldecyl ascorbate is more stable in solution, less irritating and able to penetrate deeper into the skin, making it a promising vitamin C treatment.
What are other uses of L-ascorbic acid?
L-ascorbic acid might be used as a combination therapy for other skin conditions. Vitamin C has been used to support treatments for progressive pigmented purpuric dermatosis (PPPD), allergic contact dermatitis, scarring and vitiligo. Both the topical and oral form are often used alongside other drugs and supplementation.
References:Al-Niami, F & Chiang, N 2017. ‘Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications’, The Journal of Clinical and Aesthetic Dermatology, vol. 10, is. 7, pp. 14-17.
Chen, L, Hu, J, Wang, S 2012. ‘The role of antioxidants in photoprotection: A critical review’, Journal of the American Academy of Dermatology, vol 67, is. 5, pp.1013-1024.
Murray, J, Burch, J, Streilein, R, Iannacchione, M, Hall, R & Pinnell, S 2008. ‘A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid, provided protection for human skin against damage caused by ultraviolet radiation’ Journal of the American Academy of Dermatology, vol. 59, is. 3, pp. 418-425.
Pinnell, S, Yang, H, Omar, M, Monteiro-Riviere, N, DeBuys, H, Walker, L, Wang, Y & Levine, M 2001. ‘Topical L-ascorbic Acid: Percutaneous Absorption Studies’, Dermatol Surg, vol.27, is. 2, pp.137-142.
Pullar, J, Carr, A & Vissers, M 2017. ‘The Roles of Vitamin C in Skin Health’ Nutrients, vol. 9, is. 8, pp. 866.
Telang, P 2013. ‘Vitamin C in dermatology’ Indian Dermatology Online Journal, Vol. 4, is. 2, pp. 143-146.
Yatskayer, M, Oresajo, C, Bhushan, P, Yano, S & Stephens, T 2011. ‘Clinical evaluation of an antioxidant gel cream containing vitamin c, ferulic acid and phloretin on photodamaged skin’, Journal of the American Academy of Dermatology, vol. 64, is. 2, pp. 24.
Wang, K, Jiang, H, Li, W, Qiang, M, Dong, T & Li, H 2018. ‘Role of Vitamin C in Skin Diseases’, Frontiers in Physiology, vol. 9, pp. 819.