Skin Lightening Properties of Ascorbic Acid

Popularly known as vitamin C in its primary form, L-ascorbic acid has a proven track record for improving the appearance of aging skin; no wonder it is the most common antioxidant ingredient in OTC skin care products. Vitamin C stimulates formation of collagen, which is the natural cement and scaffolding found throughout the body. It also plays a role as a water-soluble antioxidant that helps prevent free radical damage to cells.

This column will briefly review the skin lightning properties of vitamin C.

Skin Lightening

Vitamins C and E behave as antioxidants by protecting cells from oxidized compounds and free radicals by giving up their electrons to compounds that need them. This action keeps those compounds from going out and injuring other molecules. Humans lack the enzyme necessary for synthesizing vitamin C, so they must obtain it through oral ingestion or topical application.¹

Topical application has shown to be superior for replenishing skin concentrations of vitamin C.2 Researchers have identified three vitamin C derivatives— magnesium ascorbyl  phosphate,  sodium ascorbyl  phosphate and ascorbyl-glucoside—all with improved stability that efficiently convert to L-ascorbic acid in the skin to leave it firmer, healthier and more youthful.^3,4 OTC creams that contain vitamins C and A, and/or soy, all have a mild pigment-lightening effect. This lightening process can be accelerated using home peels and home micro-dermabrasion as exfoliation enables actives to more effectively penetrate skin. Clinical studies have shown that ascorbyl glucoside safely modulates common forms of hyper-pigmentation such as: age spots and difficult-to-treat melisma.^5,6 This stems from its ability to block the action of tyrosinase, a key enzyme involved in the formation of new melanin.^7,8

In one clinical study, patients ages 30 to 50 with facial hyperpigmentation applied an ascorbyl glucoside topical formula to one side of their face daily for four weeks. At the end of the study, the treated side of the panelists’ faces showed a significant reduction in total area of hyper pigmented spots. Furthermore, 70% of subjects treated with ascorbyl glucoside reported lighter skin compared to 16.6% in the untreated group.⁹

Another popular ingredient is a stabilized derivative of vitamin C called magnesium ascorbyl phosphate or MAP. It inhibits tyrosinase, the main pigment forming enzyme.
Research has shown that MAP enhances the skin’s ability to retain water, making it visibly softer and smoother.^10,11 In a controlled clinical study, human volunteers applied topical MAP to their forearm skin daily for four weeks. Researchers used corneometry and cutometery to objectively measure skin hydration. By these measures, MAP significantly increases hydration in both the outer and deeper layers of the skin, thereby demonstrating sustained effects.¹⁰ This finding was later confirmed in yet another trial.¹¹

Formulations

Vitamin C inhibits tyrosinase, but not as effectively as other agents. MAP is a stable derivative of ascorbic acid and can suppress melanin formation at levels of 3-10%. It is converted to vitamin C in the skin by non-specific esterases. Barnet Products supplies BV-OSC (Tetrahexyl decyl ascorbate), a very stable oil-soluble vitamin C. It penetrates the cells more effectively which is confirmed by data on keratinocytes, and fibroblasts. It reduces melanin synthesis by 80%. It is approved as a quasi-drug skin lightener in Japan.

Vitamin C-based products should be formulated at a low pH to help skin absorb the vitamin. Product jars should be kept airtight to prevent oxidation. These products have been shown to penetrate the skin and protect against free radical formation. Although adverse effects are minimal, ascorbic acid is relatively ineffective when used alone. Therefore it is usually combined with other agents such as licorice extract, according to Zoe Diana Draelos, MD. It helps to formulate the product with ferulic acid, a powerful free radical scavenger slows down the breakdown of vitamin C and enhances its protective effects against ultraviolet damage. When added to a combination of vitamin C and E, ferulic acid doubled its photo-protection properties from 4- to 8-fold.¹²

To be effective, lightening products must be formulated in a high concentration of at least 5% or greater strength of active material. There are brightening formulations that combine retinol and vitamin C for brightening. Every clinical study has proved that stabilized forms of vitamin C in its active form as L-ascorbic acid has multiple skin benefits, but its susceptibility to oxidation limits its stability in topical preparations. 

References:

1. Naidu, K.A., et. al., Nutr. J. 2003: 2:7
2. Telang, P.S., Indian. Derm. Online J. 2013:4 (2):143-6
3. Austria, R., et. al., J. Pharm. Biomed. Anal. 1997:15(6) 795-801
4. Knaggs, H. Cosmet. Derm. 2009:8(2) 77-82
5. Taylor, M.B., et. al.,  J. Drugs. Derm. 2013:12(1) 45-50
6. Kinetiktech.com/brochures/pdf/rahn leaflet
7. Sarkar, R., et. al.  J. Cutan. Aesth. Surg. 2013, 6(1): 4-11
8. E Banks, J.P., et. al, Int. J. Mol. Sci 2009: 10(9):4066-87
9. Hakozaki T., et al. Skin Res. Tech. 2006-12(2): 105-13.
10. Campos P.M., et al. Skin Res. Tech. 2008:14(3): 376-80
11. Campos P.M., et al. Photochem. Photobiol.2012:88(3): 748-52
12. Lin F. et al. J. Invest. Derm. 2005:125(4) 826:32

---

Navin M. Geria
Senior Technical Advisor and Principal Doctors Skin Prescription
tokuho02@gmail.com 

Navin Geria, ex-Pfizer Research Fellow, is senior technical advisor and principal of the dermatological research company, Doctors Skin Prescription (DSP), Boston, founded by dermatologist David J. Goldberg, MD JD and plastic surgeons William P. Adams, MD FACS and Jason Pozner, MD. Geria has more than 30 years of experience in the personal care industry and was previously with Clairol, Warner-Lambert, Schick, Bristol-Myers and most recently, Spa Dermaceuticals. He has earned nearly 20 US patents, has been published extensively and has been both a speaker and a moderator at cosmetic industry events. www.dspskincare.com