22 June 2022
Highly favoured and recommended by doctors, vitamin C skincare is an easy and effective way to also brighten your skin, lighten pigmentation and age-proof skin. However, information regarding topical vitamin C is often confusing and sometimes, inaccurate. Adding to this confusion is the vast array of choices of vitamin C skincare available; making it overwhelming for consumers when it comes to selecting a vitamin C product for their skin. So here this is, a guide to the science, benefits and recommendations for vitamin C in skincare. I hope you find this roadmap useful!
1. Vitamin C is a potent antioxidant that protects the skin
Free radicals from UV rays and the urban environment (e.g. pollution and smoking) cause oxidative stress to the skin cells and structures. The structural damage to the skin and DNA damage to the cells accelerate signs of ageing in the skin. Some examples of early signs of ageing are hyperpigmentation, fine wrinkles and sagging. Vitamin C in the skin neutralises free radicals preventing damage to the skin.
2. Vitamin C protects against skin cancer
Excessive sun exposure is a risk factor for skin cancer. UV rays damage the DNA of cells and a very important gene called the p53 gene. The p53 gene is the key to our body’s defenses against cancer by repairing of mutated DNA in cells. Topical vitamin C (when used together with vitamin E) shows some protection against UV-induced DNA damage by affecting the p53 repair pathways.
3. Vitamin C protects the skin against UV rays of the sun including sunburns
Laboratory studies have shown that topical application of 10% vitamin C reduces UV induced sunburn by 40-60% and sunburns by 52%. To maximise UV protection in the day, combine the use of a sunscreen with a topical vitamin C.
4. Vitamin C for anti-aging effects and collagen synthesis
Vitamin C is essential for collagen synthesis in the skin. Collagen fibres form the structural framework in the skin to keep it firm, bouncy and healthy. Collagen, elastin and hyaluronic acid are depleted in the skin as we age; hence skin becomes drier, thinner, crepey and less elastic. Vitamin C is often found in skincare products to enhance the skin’s natural collagen production.
5. Vitamin C lightens hyperpigmentation
Acquired hyperpigmentation like melasma, lentigenes and post inflammory hyperpigmentation are the top 3 causes of hyerpigmentation that I see in my clinic in Singapore. One simple way to lighten these blemishes is with vitamin C. L-ascorbic acid, the active form of vitamin C reduces hyperpigmentation by inhibiting a key enzyme in the formation of melanin. You can learn more in How to Lighten Hyperpigmentation and Dark Spots with Skincare and Hyperpigmentation Disorders: Causes, Types & Treatments.
6. Vitamin C replenishes other antioxidants in the skin
Besides these benefits, vitamin C also replenishes vitamin E in the skin. Vitamin E is another antioxidant that protects cells against free radicals and maintains collagen levels in the skin. When combined together, vitamin C and E have synergistic effects on enhancing their antioxidant benefits for the skin.
Unfortunately, humans lack the ability to synthesise vitamin C and therefore we have to rely on external sources of vitamin C- either as topical vitamin C in skincare or as part of a Skinbooster cocktail that is injected into the skin1,2. More about vitamin C in Skinboosters in this review, Skinboosters: All You Need to Know About It.
Let us first discuss the topical vitamin C in skincare to reap the benefits of vitamin C on our skin. The great thing about this is that you can get vitamin C in various formulations in skincare over the counter at affordable prices.
My recommendation would be to use vitamin C at least once daily (preferably, L-ascorbic acid- and you will understand why as you read on below). Vitamin C/L-ascorbic acid is commonly found in serums or moisturiser as a long as the concentration is adequate. This is where things start to become confusing- how do you choose a vitamin C serum for your skin?
Let us first understand the basics of vitamin C so that we can understand how to choose the type of vitamin C.
There is a wide array of vitamin C serums available and a look at in the ingredient list of drugstore vitamin C serums will unveil these familiar suspects:
1. L-ascorbic acid 2. Vitamin C derivatives/ L-ascorbic acid derivatives/esters • Magnesium ascorbyl phosphate (MAP) • Sodium ascorbyl phosphate • Ascorbyl glucoside • Ascorbyl tetraisopalmitate (and many more)
Vitamin C is also known as ascorbic acid and ascorbic acid exists in 2 forms which are mirror images of each other (isomers), L-ascorbic acid and D-ascorbic acid. The only chemically active form of ascorbic acid is L-ascorbic acid; this is the form that acts on the skin to bring about all the dermatological benefits mentioned above1. D-ascorbic acid on the other hand, does nothing to the skin. L-ascorbic acid is in fact the bona fide vitamin C that works on our skin and you can consider L-ascorbic acid as ‘1st generation’ vitamin C.
Active vitamin C (L-ascorbic acid) is unstable, with sunlight exposure and high temperatures reducing its efficacy and shelf life. Skincare companies have been trying to improve the shelf life of L-ascorbic acid by introducing vitamin C derivatives or the more stylishly named ‘2nd generation vitamin C’. These derivatives supposedly promise the same results of L-ascorbic but with greater stability and longer shelf lives. Despite the popularity of ascorbic acid derivatives, the efficacy of these derivatives is still questionable.
Thankfully, there are ways to overcome L-ascorbic acid’s troublesome nature without compromising its effectiveness. One way is to reduce the pH to below 3.54. This improves both the stability of L-ascorbic acid and permeability to reach the deeper layers of the skin. A second way method would be the addition of ferulic acids (another antioxidant) to achieve both stabilisation of L-ascorbic and a pH below 3.55,6. Examples of L-ascobic acid serums that contain ferulic and a pH 3.5 are Skinceuticals’ C E Ferulic; Drunk Elephant’s C Firma.
On the other hand, Vitamin C derivatives or 2nd generation vitamin C are not always physiologically effective7,8. This is because these derivatives need to be enzymatically converted back to L-ascorbic acid to act on the skin9. On their own, these ascorbic acid derivatives or ‘2nd generation vitamin C’ are of no use to the skin when applied to skin by themselves. Exactly how much of these derivatives get eventually converted to L-ascorbic acid is also unclear9. In other words, MAP 20% is not equivalent to an L-ascorbic acid concentration of 20%.
For vitamin C or L-ascorbic acid to have an appreciable effect on your skin, the minimum effective concentration is 8%4. As the concentration of L-ascorbic acid increases, the effectiveness increases, up to 20%1,4. Beyond 20%, any additional benefit is negligible and the increased concentration might even cause skin irritation. So, look for L-ascorbic acid concentrations between 10% to 20% for best results! As for L-ascorbic acid derivatives, the idea concentration is still unknown due to a lack of rigorous trials and clinical data9.
Besides the type of vitamin C (i.e. L-ascorbic acid versus vitamin C derivatives) and the concentration of the vitamin C (ideally 10-20%), look for vitamin C formulations that also contain vitamin E and Ferulic. The addition of these two antioxidants have been found to result in a fourfold increase in protection against UV induced skin damage5,6.
Most vitamin C/L-ascorbic acid topical formulations are in the form of a serum or moisturiser. A basic sequence would be facial cleanser-serum-moisturiser-sunscreen (in the day). To learn more about how to build a skincare routine and the essentials that you need, check out my post 3 Essential Skincare Steps for Healthy Skin.
The top layer of the skin is a protective barrier designed to minimise loss of water and uptake of toxins from the environment. This presents an obstacle to skincare ingredients including vitamin C. However, by pre-treating the skin with lasers, chemical peels; the absorption of vitamin C through the skin can be enhanced10.
You might ask about taking high doses of oral vitamin C; but only a small fraction of vitamin C will be available and active in the skin11. Hence, vitamin C in skincare and as part of Skinboosters are preferred.
Intravenous vitamin C drips in Singapore for whitening is a controversial topic. Although these intravenous vitamin C drips or intravenous vitamin drips are performed in countries such as Taiwan and the US (celebrities Cara Delevingne, Rihanna and Barbie Hsu are reported to be fans of these vitamin C drips); intravenous vitamin drips for whitening and aesthetic purposes are banned by the Ministry of Health in Singapore.
These vitamin drips are known as intravenous micronutrient drips and the report benefits of these vitamin drips include: • Strengthened immune system • Improved energy levels • Improved nutrition • Faster recovery from illnesses
These benefits have been attributed to the higher levels of vitamin C in the blood that can be achieved with intravenous vitamin C than can be achieved with consuming vitamin C from food and supplements because these micronutrients are delivered directly into the blood; bypassing the absorption barrier in the gastrointestinal tract.
The use of high doses of intravenous vitamin C as a complementary treatment for cancer is currently being studied and the results have shown to be promising so far12. However, the use of intravenous vitamin drips for aesthetics in Singapore, especially for lightening complexion remains controversial as the safety and efficacy of these intravenous vitamin C drips lack sufficient data to support its use in Singapore. More about skin lightening drips in my review on Whitening Drips and Skin Bleaching Treatments.
Image credit: Newsweek
Covid-19 Update April 2020
Do Intravenous (IV) Vitamin C Drips Cure Covid-19 infections?
The use of intravenous vitamin C drips to treat infections including the flu has been controversial. Intravenous (IV) vitamin C drips deliver larger amounts of vitamin C directly into the bloodstream, as opposed to consuming oral vitamin C supplements that may not be 100% absorbed by the gastrointestinal tract.
Most of you might have heard of the advice to take vitamin C if you are unwell. The popularity of this piece of advice rose in the 1970’s when Nobel Prize winner, Dr Linus Pauling, advocated consuming vitamin C as a cure for cold. This quickly took off because it seemed to be an easy and cost effective way to strengthen one’s immunity against the cold. Now that the global spread of Covid-19 (Coronavirus) has reached unprecedented levels in modern times and there is still no cure or vaccine against Covid-19 in sight; high doses of intravenous vitamin C seem to be making a comeback in the news.
The big question is: Do IV vitamin C drips cure covid-19 infections? The short answer is no; that has yet to be proven. Research on the effect of IV vitamin C drips and the cold have also been equivocal and so the role of IV vitamin C drips in treating colds, infections and Covid-19 is not a part of mainstream treatment. There are currently trials underway to study the effects of IV vitamin C in infections, including whether IV vitamin C reduces the severity of infections.
In summary, vitamin C/L-ascorbic acid is a potent antioxidant that protects the skin from UV rays, lightens pigmentation and building collagen in the skin. Topical use of vitamin C is also very safe, making it a popular choice for dermatologists and skincare companies in anti-aging skincare and as a supplement to clinic treatments.
The only form of vitamin C that can bring about benefits to the skin is L-ascorbic acid, so remember to scrutinise the ingredient list of the skincare that you purchase. An effective concentration to choose from would be between 10-20%. Including vitamin E and ferulic in the vitamin C formulation also increases the efficacy of topical vitamin C. I would not recommend using any of the derivatives because they do not act on the skin and the conversion back to L-ascorbic acid if at all, is unknown.
Shifting the focus of this post to a little project I’ve been working on for 8 months now; my own vitamin C serum that I’ve formulated after countless revisions (and rejections). One the perks of my job is creating and curating skincare that I would use for myself and my patients. My vitamin C serum contains 20% L-ascorbic acid, 1% vitamin E and 0.5% Ferulic.
So there you go, all the essentials of vitamin C in dermatology and how to pick a vitamin C product if you would like to include it in skincare routine!
1. Cosmetical Vitamins: Vitamin C. In: Draelos ZD, Dover JS, Alam M, editors. Cosmoceuticals. Procedures in Cosmetic Dermatology. 2nd ed. New York: Saunders Elsevier; 2009. pp. 51–56. Farris.
2. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. Niaimi and Chiang. J Clin Aesthet Dermatol. 2017 Jul; 10(7): 14–17.
3. Vitamin C in Dermatology. Telang. Indian Dermatol Online J. 2013 Apr-Jun; 4(2): 143–146.
4. Topical L-ascorbic acid: percutaneous absorption studies. Pinnell et al. Dermatol Surg. 2001;27(2):137–142
5. Ferulic acid stablizes a solution of vitamins C and E and doubles its photoprotection of skin. Lin et al. J Am Acad Dermatol 2003; 48: 866–74. 33
6. Ferulic acid stabilizes a solution of vitamins C and E and DOUBLES its photoprotection of skin. Lin et al. Soc Investig Dermatol 2005; 125: 826–32.
7. Cosmeceuticals. Talakoub et al. Cosmetic dermatology. Vol. 1. Requisites in Dermatology. 1st ed. Gurgaon: Saunders Elsevier; 2009. pp. 13–4.
8. Use of Topical Ascorbic acid and its effects on Photo damaged skin topography. Traikovich. Arch Otorhinol Head Neck Surg. 1999;125:1091–8.
9. Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives. Stamford. Journal of Cosmetic Dermatology, 11, 310—317.
10. Lasers and microdermabrasion enhance and control topical delivery of vitamin C. Lee et al. J Invest Dermatol. 2003;121(5):1118–1125.
11. UVR-induced oxidative stress in human skin in vivo: effects of oral vitamin C supplementation. McArdle et al. Free Radic Biol Med. 2002;33(10):1355 –1362.
12. High Dose Vitamin C. National Cancer Institute. https://www.cancer.gov/about-cancer/treatment/cam/hp/vitamin-c-pdq