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