Skincare and Vitamin C
Vitamin C provides benefits to the body both orally (see Benefits of Oral Vitamin C) as well as topically. As a skincare ingredient, vitamin C has become pretty popular lately. Here are some reasons why vitamin C is a sought-after topical ingredient.
Vitamin C is important for skin health and is one of the most powerful antioxidants found in the skin[1,2]. It increases collagen production, stabilizes collagen fibers, and decreases collagen break down; it reduces fine lines and wrinkles; it decreases the production of melanin; and it helps protect against UV light-induced damage[1,2,3]. Because of these abilities, vitamin C has a range of clinical uses including antiaging, reducing pigmentation, and photoprotection.
Reducing free radical damage. Vitamin C is found in high amounts in the dermal and epidermal layers of the skin, amounts which decreases as we age or are exposed to UV light and pollutants. UV exposure can result in the production of free radicals, toxic molecules that can damage proteins, cell membranes, and nucleic acids (which are important for DNA). These free radicals also lead to reduced collagen production and increased collagen destruction, which in turn can result in pigmentation, telangiectasias, coarse skin texture, photoaging, and deep wrinkles. Vitamin C has a role in reducing this damage.
Protective immune cell response. Epidermal cells in the skin also have a protective immune response, which can be negatively affected by acute and chronic UV exposure. Topical vitamin C solutions have been shown to prevent decreases in these important immune cells.
Reducing pigmentation. Pigmentation can occur in the skin when tyrosine is converted to melanin. An enzyme called tyrosinase is responsible for this conversion. Vitamin C actually blocks the action of this enzyme, resulting in decreased melanin formation and reduced pigmentation.
Finding a Stable & Effective Formulation
For vitamin C to be useful topically, it must be formulated so that it remains effective over time. Exposure to both air and light can affect its stability, so packaging of vitamin C is also important. Product should be stored in opaque containers that restrict air, like a pump, not a dropper bottle or tub that is continually opened and exposed to the air. A vitamin C serum should be colourless or a light beige; if yellow or brown, it has likely been oxidized and won’t be as effective. If it’s brown, it’s time to toss it!
Products can contain different concentrations of vitamin C. In most situations, the concentration of vitamin C must be higher than 8% to be useful. However, for dry/sensitive skin, lower concentrations are less irritating (eg around 5%). If using for hyperpigmentation, concentrations up to 20% can be used - studies have shown there is usually no added benefit for concentrations higher than this, and they are more likely to cause irritation[1,2,4]. Therefore, most trusted products have a concentration between 10-20%[2 ].
Another important factor to consider is how well the formulation is absorbed into the skin. The most common form of vitamin C, L-ascorbic acid, is the most effective for topical application and the most well-studied, but is also the least stable[1,2,3]. It is water soluble, which means it does not penetrate into the skin very well - the upper skin layer, the stratum corneum, is hydrophobic, meaning it repels water. By decreasing the acidity of L-ascorbic acid to a pH below 3.5, both stability and permeability can be improved, helping with penetration. This is why you may see some vitamin C products contain ferulic acid - this is used to help adjust the formulation to a desirable pH. Other common topical formulations of vitamin C include ascorbyl-6-palmitate and magnesium ascorbyl phosphate (MAP). Disodium isostearyl 2-0 L-ascorbyl phosphate, ascorbic acid sulphate, and tetraisopalmitoyl ascorbic acid are other stable derivatives. Some small studies have also shown that penetration into the skin can be increased with laser resurfacing, microdermabrasion, ultrasound, and nanoparticles.
Using Vitamin C Properly
As vitamin C can help protect against free radicals from UV radiation, you may get the most benefit from applying a vitamin C product in the morning. Don’t use vitamin C at the same time as benzoyl peroxide, which decreases vitamin C potency. Exfoliating scrubs or acids with vitamin C are also not a good idea as skin is more easily irritated. Retinol also works similarly to vitamin C, so it is best to also avoid combining these ingredients. If you are using a vitamin C product as well as a retinoid, it’s best to space them apart (ie one in the morning, the other in the evening)!
Hopefully this gave you a basic understanding of topical vitamin C benefits for the skin. For more information, check out my other blog post on oral vitamin C, or my review of vitamin C skincare products (coming next)!
Michels, A.J. Vitamin C and Skin Health. Linus Pauling Institute. Oregon State University, September 2011. Retrieved 14Mar2021 from https://lpi.oregonstate.edu/mic/health-disease/skin-health/vitamin-C
Al-Niaimi, F. and Chiang, N.Y.Z. Topical vitamin C and the skin: Mechanisms of action and clinical applications. J Clin Aesthet Dermatol. 2017;10(7):14-17.
Ngan, V. Topical vitamin C. DermNet NZ, 2002. Retrieved 14Mar2021 from https://dermnetnz.org/topics/topical-vitamin-c/.
Jacoby, S. 9 Things you need to know before using vitamin C for your skin. SELF, January 29, 2020. Retrieved 14Mar2021 from https://www.self.com/story/vitamin-c-for-skin-tips.
DISCLAIMER: The contents of this blog are for educational purposes and are not intended as medical advice. I enjoy researching but the information is general and not comprehensive. Please seek the advice of your healthcare provider (pharmacist/physician etc) with any questions you may have regarding your personal health. Never disregard professional medical advice or delay in seeking it because of something you have read online. Any mention of specific products or personal recommendations are my opinion and not to be taken as medical advice.