In-depth ingredient analysis: Vitamin C (ascorbic acid)

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  1. Documented benefits of topical vitamin C on skin
  2. Bioavailability of topical vitamin C for skin 
  3. Vitamin C derivatives
  4. Bibliography

Did you know? This might surprise you, but the most abundant antioxidant naturally found in human skin is vitamin C. Moreover, an adequate concentration of vitamin C in the skin is essential for the organ to be fully functional, making it a key factor to support the overall health and look of skin.

Anti-aging superstar, vitamin C is a science-backed skincare ingredient you can be sure will benefit your skin. The effects of topical application of vitamin C on skin have been documented by numerous studies that have confirmed its benefits. Not just another ephemeral hype, the use of this antioxidant in skincare is here to stay. Vitamin C now plays a central role in premature skin aging prevention strategies, thanks to its wide range of proven benefits.

1. Documented benefits of topical vitamin C on skin

  • An effective free-radical scavenging antioxidant

Every day the skin’s surface is exposed to a multitude of external aggressors, regardless of an individual’s lifestyle choices, healthy or not. Exposure to UV light, air pollution and secondhand cigarette smoke, for example, all generate free radicals that can accelerate skin aging. Indeed, free radicals are strongly unstable and toxic molecules. They cause oxidative stress, which exposes the skin tissue to significant damage like compromised cell membranes, alterations of the cellular DNA or collagen destruction. But don’t panic! You can protect your skin from daily oxidative stress by integrating topical vitamin C into your skincare routine. The antioxidant will neutralize free radicals, rendering them harmless.

  • UV protection optimization (photoaging protection)

Let’s be clear: Vitamin C is in no way an alternative to sunscreen. The latter (which we should all wear daily!) protects skin from sunlight exposure by absorbing or reflecting harmful UVA and UVB radiation; vitamin C doesn’t.

However, here’s another surprising fact: sunscreens only block 55% of the free radicals generated by exposure to UV light (Telang, 2013).

That’s why it’s recommended to apply sunscreen in conjunction with a topical antioxidant product for the ultimate sun protection. Vitamin C neutralizes the UVA and UVB induced free radicals that sunscreen would otherwise let through. Tests under laboratory conditions using a 10% topical vitamin C product showed a reduction of sunburn cell formation by 40 to 60% (Telang, 2013). Not bad. Finally, UV rays also deplete the vitamin C levels of skin tissue, making it interesting to apply some more at night, after sun exposure. This will support the skins nighttime reparative process.

PS: It’s a well-known and researched fact that chronic exposure to UV light (even if minimal) is the most significant cause of premature skin aging. It’s also extremely common. This is probably why specific terms are used to designate sunlight related aging, like photodamage and photoaging. The visible consequences are dramatic: early formation of wrinkles, multiplication of dark spots and destruction of the skin’s structure (hello sagging, sallow and rougher skin). Then there’s the very serious risk of developing skin cancer. Nonetheless, photodamage isn’t a fatality. You can protect yourself! You are worth the effort 🙂

  • Reducing signs of sun damage (photoaging treatment):

A study I came across evaluated the effects of topical vitamin C on photoaged skin. Optical profilometry image analysis was used to evaluate 2 parameters of skin roughness (Ra and Rz) after 3 months of use. The research demonstrated a 73.7% greater improvement in the Ra parameter for the treated group versus the control group, as well as 68.4% greater improvement in the Rz parameter for the treated group compared to the vehicle control (Traikovich, 1999). However, another much more recent study supported the effectiveness of topical vitamin C in the prevention UV radiation damage but qualified the treatment of photoaged skin after chronic sun damage as “much more problematic” (The Roles of Vitamin C in Skin Health, 2017).

// As always, prevention is key  //

  • Increase volume and quality your skin’s collagen production

Scientific studies all agree on the essential role of vitamin C in collagen production. Treating skin with topical vitamin C increases the volume of collagen synthesis, stabilizes collagen fibers (enhances their quality) and decreases collagen degradation (Al-Niaimi, F., & Chiang, 2017). Amazing right?  Don’t we all love producing collagen 😉

Another interesting fact: A clinical study demonstrated that topical Vitamin C increases collagen production in young as well as aged human skin (Farris PK, 2005).

  • Boost the skin’s radiance and luminosity

Nourishing the skin with vitamin C will energize dull-looking skin. You might be amazed by the healthy and youthful glow it gives you. This is usually the most direct and visible benefit of vitamin C for skin. Works wonders to get a perfectly vibrant skin tone.

See, you don’t ever need to tan to look healthy.

  • Reduce hyperpigmentation (dark spots / uneven complexion):

Vitamin C is categorized as a depigmenting or anti-pigmenting agent because it’s proven to decrease the production of melanin by the skin. It actually interrupts key steps of melanogenesis. By doing so, the antioxidant should reduce hyperpigmentation in the long run – patience will be required (Al-Niaimi, F., & Chiang, 2017)

Although vitamin C can help fade away hyperpigmentation, it’s not as effective as Hydroquinone or Licorice extracts to treat this particular issue.

  • Support skin tissue healing:

A few studies mention the potential of topical vitamin C to assist skin tissue in its healing process for a better-looking wound. It would even minimize the formation of raised or keloid scars (The Roles of Vitamin C in Skin Health, 2017).

2. Bioavailability of topical vitamin C for the skin

  • Particularities of Ascorbic Acid (AA) and  L-Ascorbic Acid (LAA)

Both terms are used to designate the same molecule: pure vitamin C. It is the most chemically active form of vitamin C, meaning it’s the most potent one. It’s also the most studied form. This is what you should look for in order to enjoy the full benefits of topical vitamin C. The water-soluble molecule also happens to be highly unstable. When buying or using an AA/LAA labeled product, it’s essential to make sure to respect certain requirements ensuring the stability and effectiveness of this active form of vitamin C.

  • Product conservation: minimize exposition to light, air, and heat

To preserve the integrity of the unstable molecule, an opaque container is mandatory. It should also be the most airtight possible. Be extra careful not to leave it open after using it. Finally, keep your vitamin c serum in the refrigerator to extend its lifespan (very effective!). If the serum oxidizes (meaning it turns bad), it will change color to turn yellow. Throw it away, it won’t provide your skin any benefit after that.

  • Product pH level: under 3.5

The stability of (l-)ascorbic acid is greatly increased when contained in a product with a pH of less than 3.5. A low pH level also significantly increases the skin penetration capacity of the molecule (permeability).

  • Waiting time before applying other products: 20 mins

To ensure the full effectiveness of most (l-)ascorbic acid serums, it is recommended to wait for the skin to fully absorb the serum (ideally 20 mins), before applying other products that would make the pH level of the skin surface go up.

The antioxidant should be applied right after washing your face with a low pH cleanser, or after applying a low pH toner.

  • The optimal concentration level of vitamin C in facial serums: Between 10% and 20%

Clinical studies have revealed that the maximal absorption level of (l-)ascorbic acid was attained with serums formulated at a concentration of 20%. Higher concentrations of (l-)ascorbic acid might even lower absorption level (4)Significant results have been observed with concentrations as low as 10%. (1)

  • Combining Vitamin C, vitamin E, and ferulic acid in skincare:

Several studies have put forward the positive synergy between these antioxidants. The combination of Vitamin C and vitamin E makes them particularly effective at preventing UV light damage and reducing oxidative stress to the skin. Ferulic acid greatly helps to maintain the stability of (l-)ascorbic acid.

  • Oral vitamin C supplementation VS topical vitamin C skincare:

The studies I’ve read indicate that applying a topical vitamin C serum is the most effective and direct way to deliver vitamin C to the skin. It’s the way to go if you want to provide skin extra UV protection. One of the research papers consulted clearly states that the bioavailability of Vitamin C for skin is insufficient if taken orally. Topical application of (l-)ascorbic is to be preferred in dermatology.

3. Vitamin C derivatives (esters) 

Because of the inherent difficulties surrounding the conservation and application of (l-)ascorbic acid, recent research has been focused on finding stable forms of vitamin C and new methods of delivery into the dermis. As a result, a lot of new  Vit. C derivatives have been introduced to the market in the last years, like:

  • Magnesium ascorbyl phosphate (MAP)
  • Ascorbyl 6 palmitate
  • Disodium isostearyl 2-0
  • Ascorbic acid sulfate
  • sodium ascorbate
  • Tetraisopalmitoyl ascorbic acid

The synthetic derivatives have been designed to be stable, but present clinical studies suggest they have a mostly insignificant impact on skin. The derivatives need to be converted into (l-)ascorbic acid by the skin in order to be used, with limited results. Absorption of derivatives by the skin is poor. (1)

4. Bibliography

(1) Al-Niaimi, F., & Chiang, N. Y. Z. (2017). Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. The Journal of Clinical and Aesthetic Dermatology10(7), 14–17.

(2) Farris PK. (2005) Topical vitamin C: a useful agent for treating photoaging and other dermatologic conditions. Dermatol Surg. 2005;31(7 Pt 2):814–817

(3) Pullar, J. M., Carr, A. C., & Vissers, M. C. M. (2017). The Roles of Vitamin C in Skin Health. Nutrients, 9(8), 866.

(4) Telang, P. S. (2013). Vitamin C in dermatology. Indian Dermatology Online Journal4(2), 143–146.

(5) Traikovich SS. (1999). Use of topical ascorbic acid and its effects on photodamaged skin topography. Arch Otolaryngol Head Neck Surg. 1999 Oct;125(10):1091-8.

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