Vitamin C (ascorbic acid) is one of the four most important ingredients in skin care products.

• It is proven to increase collagen production when applied topically to skin.

• It inhibits tyrosinase to even skin tone and has a strong antioxidant activity.

• It is absorbed well orally, but not enough gets to the skin.

• It is best absorbed at a pH of 2.0.

• It is unstable when exposed to light and air. Instruct patients to discard 6 months after opening.

In addition, the proper formulation is patented and expensive. Stick with brands you trust. Use vitamin C on skin prior to procedures to speed healing. It will sting when used on inflamed skin because of the low pH.

In my opinion, all patients need to be on the proper skin care regimen for their skin type. This includes a daily sun protection factor (SPF), a cleanser, a retinoid, and an antioxidant. Ascorbic acid is one of my favorite antioxidants because it is the only one shown to increase the production of collagen by fibroblasts and inhibit tyrosinase while scavenging free radicals. Sure it is expensive – but that is because formulating and packaging it properly is expensive. Unfortunately, many subpar brands have entered the market. Ask to see the company’s research data on its formulation before choosing to recommend or sell ascorbic acid/vitamin C in your practice.

An essential water-soluble nutrient for the development of bone and connective tissue, vitamin C is found in citrus fruits and green leafy vegetables. It is produced in most plants and animals, but a mutated gene in humans has resulted in a deficiency of L-gulono-gamma-lactone oxidase, the enzyme required for its production.1,2 Although ascorbic acid cannot be synthesized by the human body, dietary consumption renders it the most abundant antioxidant in human skin and blood, and vitamin C plays an important role in endogenous collagen production and the inhibition of collagen degradation.3-6 Ascorbic acid also is known to regenerate alpha-tocopherol (vitamin E) levels and, therefore, is thought to protect against diseases related to oxidative stress.7

Epidermal vitamin C can be depleted by sunlight and environmental pollution, such as ozone in urban pollution.8,9 Known to exhibit a wide range of biologic activities, ascorbic acid has been shown to deliver rejuvenating effects on skin wrinkles, texture, strength, and evenness of tone through its antioxidant, tyrosinase-inhibiting, and collagen production-promoting activities.10 Indeed, as a topical agent, vitamin C has been used to prevent photodamage, and to treat melasma, striae alba, and postoperative erythema in laser patients.11,12 It is regularly used to treat aging skin, and as a depigmenting agent.2,10,13 This column will discuss the antioxidant, antiaging, and depigmenting activity of vitamin C in the context of recent human studies.

Antioxidant and anti-aging activity

Vitamin C is unique among antioxidants because of its ability to increase collagen production in addition to its free radical scavenging antioxidant activity. Due to its capacity to interfere with the UV-induced generation of reactive oxygen species by reacting with the superoxide anion or the hydroxyl radical, vitamin C has become a popular addition to “after-sun” products,14,15 and been shown to be effective in mitigating the effects of UVB, such as erythema and signs of photoaging, on porcine and human skin.2,16-17

A 2001 study in 10 postmenopausal women by Nusgens et al. found that daily topical application of 5% L-ascorbic acid enhanced the levels of procollagen types I and III, their posttranslational maturation enzymes, and tissue inhibitor of matrix metalloproteinase.18 This led to increased levels of collagen in the skin.

In 2003, Humbert et al. conducted a 6-month, double-blind, vehicle-controlled trial with 20 healthy female volunteers showing that patients treated with 5% vitamin C cream experienced significant improvements in deep furrows on the neck and forearms.19

In a small study of nine adults with Fitzpatrick skin types II or III in 2008, Murray et al. studied whether a stable topical preparation of 15% L-ascorbic acid, 1% alpha-tocopherol, and 0.5% ferulic acid could protect human skin in vivo from UV-induced damage. They found that the antioxidant formulation supplemented the antioxidant pool of the skin and conferred significant photoprotection, guarding the skin against erythema and apoptosis as well as effectively suppressing p53 activation and reducing thymine dimer mutations known to be associated with skin cancer.13

In 2012, Xu et al. evaluated the efficacy and safety of topical 23.8% L-ascorbic acid on photoaged skin in a split-face study of 20 Chinese women. Significant improvements in fine lines, dyspigmentation, and surface roughness were observed, without adverse side effects.20

In a 2015 study of 60 healthy female subjects, Crisan et al. used high-frequency ultrasound to determine that the use of a topical vitamin C formulation yielded significant increases in collagen synthesis, revealing the solution to be an effective rejuvenation therapy.21

Skin lightening activity

Melasma

In 2004, Espinal-Perez et al. conducted a double-blind randomized trial of 5% ascorbic acid, compared with 4% hydroquinone (HQ) water–oil emulsion in 16 female patients with melasma, aged 23-43 years (mean 36 years). Of those treated with vitamin C, 62.5% exhibited good or excellent subjectively assessed skin lightening. There was no statistically significant difference in depigmenting activity in the HQ group, of which 68.7% experienced irritation whereas vitamin C was well tolerated.22

In a randomized, double-blind, placebo-controlled study, researchers used iontophoresis to enhance the penetration of vitamin C into the skin and significantly reduce pigmentation, compared with placebo.23

Although ascorbic acid is viewed by many as ineffective as a depigmenting agent alone, particularly in 5%-10% concentrations, when used in combination with other ingredients such as HQ, it is considered effective.24 In the magnesium-L-ascorbyl-2-phosphate esterified form, however, vitamin C is among the most popular prescribed depigmenting agents around the world, especially in countries where HQ and its derivatives are prohibited.25 In a 2009 16-week open-label study by Hwang et al. of 25% L-ascorbic acid and a chemical penetration enhancer for treating melasma in 40 patients, researchers observed significant reductions in pigmentation.26

In a small split-face study early in 2015, Lee et al. showed that the combination of 1,064-nm Q-switched neodymium-doped yttrium aluminum garnet (QS-Nd:YAG) laser and ultrasonic application of vitamin C was more effective than was the laser treatment alone in achieving a cosmetically acceptable treatment for melasma.27

PIPA

Vitamin C can be used to diminish or prevent post-inflammatory pigment alteration (PIPA) after procedures because it inhibits tyrosinase, lowers inflammation, and quenches free radicals. In a study of 10 patients, the application of topical vitamin C 2 or more weeks after surgery reduced the duration and degree of erythema after skin resurfacing with a carbon dioxide laser.28

Stretch marks

The depigmenting effects of vitamin C can lighten the pigmentation associated with stretch marks and its anti-inflammatory activity can contribute to blunting related redness.12

Conclusion

Although orally administered ascorbic acid is readily bioavailable, ascorbic acid in the skin is quickly depleted and oral supplementation alone does not yield optimal skin levels. Therefore, topical use of vitamin C is desirable. In fact, I tell my patients to use it topically in the morning and add a vitamin C supplement to their diet. Numerous formulation considerations (e.g., packaging, exposure to air or light during use, skin sensitivity, and user preference) are involved in the stabilization and effective penetration of ascorbic acid into the skin, and the process of developing, manufacturing, and packaging of effective, stable vitamin C products is expensive.

Vitamin C, particularly when combined with other ingredients, has been shown to be an integral constituent in topical antioxidant, antiaging, and depigmenting formulations that show promise in the dermatologic armamentarium. It is a great choice for use in a prep-procedure skin care regimen to speed healing. Use after a procedure is prohibited by the stinging associated with the low pH of properly formulated products.

References

1. J Biol Chem. 1994 May 6;269(18):13685-8 .

2. Dermatol Surg. 2001 Feb;27(2):137-42 .

3. J Invest Dermatol. 1994 Jan;102(1):122-4 .

4. Dermatol Surg. 2005 Jul;31(7 Pt 2):814-7 .

5. Annu Rev Nutr. 1994;14:371-91 .

6. J Drugs Dermatol. 2008 Jul;7(7 Suppl):s2-6.

7. J Am Acad Dermatol. 2003 Jun;48(6):866-74.

8. J Invest Dermatol. 1994 Apr;102(4):470-5.

9. Free Radic Biol Med. 1997;23:85-91.

10. J Drugs Dermatol. 2014 Oct;13(10):1208-13.

11. J Am Acad Dermatol. 1996 Jan;34(1):29-33.

12. Dermatol Surg. 1998 Aug;24(8):849-56.

13. J Am Acad Dermatol. 2008 Sep;59(3):418-25 .

14. J Biol Chem. 1983 Jun 10;258(11):6695-7.

15. J Phys Chem. 1983;87:1809-12 .

16. Br J Dermatol. 1992 Sep;127(3):247-53.

17. J Invest Dermatol. 1991;96:587.

18. J Invest Dermatol. 2001 Jun;116(6):853-9.

19. Exp Dermatol. 2003 Jun;12(3):237-44.

20. J Drugs Dermatol. 2012 Jan;11(1):51-6.

21. Clin Cosmet Investig Dermatol. 2015 Sep 2;8:463-70

22. Int J Dermatol. 2004 Aug;43(8):604-7.

23. Dermatology. 2003;206(4):316-20.

24. Am J Clin Dermatol. 2011 Apr 1;12(2):87-99.

25. Phytother Res. 2006 Nov;20(11):921-34.

26. J Cutan Med Surg. 2009 Mar-Apr;13(2):74-81.

27. Lasers Med Sci. 2015 Jan;30(1):159-63.

28. Dermatol Surg. 1998 Mar;24(3):331-4.

Dr. Baumann is chief executive officer of the Baumann Cosmetic & Research Institute in the Design District in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote the textbook “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002), and a book for consumers, “The Skin Type Solution” (New York: Bantam Dell, 2006). Her latest book, “Cosmeceuticals and Cosmetic Ingredients,” was published in November 2014. Dr. Baumann has received funding for clinical grants from Allergan, Aveeno, Avon Products, Evolus, Galderma, GlaxoSmithKline, Kythera Biopharmaceuticals, Mary Kay, Medicis Pharmaceuticals, Neutrogena, Philosophy, Topix Pharmaceuticals, and Unilever.

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