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Vitamin C for Skin Discolorations, Wrinkles and Antioxidant Support

What is Vitamin C and why is it so good for the skin? 
Vitamin C, also known as Ascorbic Acid, is a much beloved ingredient in clinical skincare, and for good reason. It’s one of relatively few ingredients in skincare that has a number of published clinical studies demonstrating its ability to improve the appearance of skin discolorations and wrinkles. It is also a powerful antioxidant, helping to support skin against free radicals produced by exposure to sun and pollution.

Vitamin C for Skin Discolorations, Wrinkles and Antioxidant Support

Ascorbic acid is naturally found in the body, including in the skin, where it serves as one of skin’s main antioxidants. Interestingly, while most animals can produce their own ascorbic acid, humans (along with other primates and guinea pigs) have lost this ability, and therefore must obtain their ascorbic acid from dietary sources. While the ascorbic acid that we obtain through eating fruits and vegetables does eventually reach our skin, it would be impossible to reach the high levels obtained by saturating skin with ascorbic acid topically. Research demonstrating the benefits of topical application of ascorbic acid most often used concentrations between 5% and 25%. 

Note: Ascorbic acid is the biologically active and most well-researched “form” of Vitamin C. Derivatives of Vitamin C are numerous and vary in the amount of evidence behind them. 

Vitamin C and Skin Brightening: What the Research Says

There are a number of studies that support ascorbic acid’s reputation for improving the appearance of skin discolorations and brightness. Though not an apples-to-apples comparison because of the different delivery systems, the data directionally points to a concentration of 5% to 25% ascorbic acid used over a period of 12-16 weeks as being potentially efficacious and well-tolerated when used to improve the appearance of skin tone evenness.

In 2004, Liliana Elizabeth Espinal-Perez and team conducted a 16-week, positive-controlled, split-face clinical study comparing 5% ascorbic acid and 4% hydroquinone in their ability to improve the appearance of skin discolorations on the faces of 16 participants. Improvement was measured by instrumentation (DermaSpect) and subjective self-assessments (4-grade scale of improvement). Improvement in the appearance of discoloration was evaluated as being comparable when measured by instrumentation, though subjective self-assessments rated the improvement with hydroquinone as being greater than with ascorbic acid. However, ascorbic acid had the advantage of considerably less irritation. 

In 2009, Seon-Wook Hwang and team conducted a 16-week clinical study to evaluate a 25% ascorbic acid treatment’s ability to improve the appearance of skin discolorations on the faces of 40 participants. Improvement was measured by clinician grading and instrumentation (Mexameter). After 16 weeks, there was a significant improvement in the appearance of discolorations as measured by both clinician grading and instrumentation. Out of the 40 patients, 30 experienced stinging, 23 experienced burning, 8 experienced redness, 6 experienced itchiness and 5 experienced scaling. The researchers noted that these effects did not prevent any participants from completing the study and that the side effects resolved within 2 weeks. 

In 2011, Abdallah Kehmis and team conducted a 3-month, negative-controlled, split-body study (with application on face, hands and arms), with an 2-month follow-up phase, to evaluate the ability of a 10% ascorbic acid and 2% phytic acid combination treatment to improve the appearance of skin discolorations in 30 participants. Improvement was measured by clinician grading and instrumentation (Chromameter and Dermascopy). After 12 weeks of treatment, the improvement in the appearance of discolorations was significant as measured by both clinician grading and instrumentation. 2 subjects experienced redness, 2 experienced tingling, and 1 experienced itching. The researchers considered these to be mild and described the treatment as being well-tolerated. 

Vitamin C and Skin Wrinkles:  What the Research Says

A number of studies in the published literature demonstrate ascorbic acid’s potential to improve the appearance of fine lines and wrinkles. Though the data is not perfect because of differences in delivery systems and study design, the data directionally points to a concentration of 5% or greater of ascorbic acid used over a period of 12-weeks or more as being potentially efficacious and well-tolerated when used to improve the appearance of wrinkles and fine lines.

In 1999, Steven Traikovich conducted a 3-month, negative-controlled, split-face study, to evaluate the ability of a 10% ascorbic acid treatment to improve the appearance of wrinkling and other signs of photoaging in 19 subjects as measured by both clinician grading and instrumentation (optical profilometry image analysis). After 12 weeks of treatment, the improvement in the appearance of wrinkling was significant as measured by both clinician grading and instrumentation. Adverse effects were described as being mild and resolving within the first 2 months of treatment, and included stinging (55%), redness (24%), and dry skin (.05%). 

In 2002, Richard Fitzpatrick and Elizabeth Rostan conducted a 12-week, negative-controlled, split-face study to evaluate the ability of a 10% ascorbic acid and 7% tetrahexyldecyl ascorbate combination treatment to improve the appearance of wrinkling and other signs of photoaging in 10 subjects as measured by clinician grading. Biopsies were also performed in 4 patients and studied for epidermal thickness and collagen content. After 12 weeks of treatment, the improvement in the appearance of wrinkling was significant as measured by clinician grading. Researchers did not comment on adverse effects other than to note that there was no clinical or histologic evidence of inflammation. 

In 2003, Philippe Humbert and team conducted a 6-month, negative-controlled, split-body study (with application to the lower neck and forearms), to evaluate the ability of a 5% ascorbic acid treatment to improve the appearance of wrinkling in 20 participants. Improvement in the appearance of wrinkling was measured by clinician grading and instrumentation (topographic measurements of wrinkling via silicone skin molds). Skin biopsies were also collected for analysis. Improvements in the appearance of wrinkling were significant as measured by both clinician grading and instrumentation. Researchers did not comment on any adverse effects. 

Vitamin C and Antioxidant Support:

Ascorbic acid is well-known as an antioxidant and free radical scavenger. What this means in the context of actual skincare use can sometimes feel vague. Of the studies demonstrating ascorbic acid’s antioxidant power, there are two that are particularly notable for their real-life applicability.

In 2008, John Murray and team conducted a 5-day study to evaluate the antioxidant effect of a 15% ascorbic acid, 1% alpha-tocopherol and .5% ferulic acid treatment in 9 subjects. The treatment and a placebo were applied to the skin on the backs of participants for 4 consecutive days, and then exposed to controlled doses of solar-simulated energy on day 4. One day later, skin was visually evaluated by clinicians and biopsy specimens were collected for analysis. Results indicated that the ascorbic acid, alpha-tocopherol and ferulic acid combination treatment resulted in significantly less signs of free radical damage than the placebo, as measured by skin redness and histological analysis.

A similar study in 2008 by Christian Oresajo and team sought to evaluate the antioxidant effect of a 10% ascorbic acid, .5% ferulic acid and 2% phloretin treatment in 10 subjects. The treatment and a placebo were applied to the backs of participants for 4 consecutive days and then exposed to controlled doses of solar-simulated energy on day 4. One day later, skin was visually evaluated by clinicians and biopsy specimens were collected for analysis. Similar to Murray and team’s study, results indicated that the ascorbic acid, ferulic acid and phloretin combination treatment resulted in significantly less signs of free radical damage than the placebo, as measured by skin redness and histological analysis.

Vitamin C and Stability

It’s important to note that ascorbic acid is very unstable, and is rapidly oxidized when exposed to light air, and water. Therefore, limiting its exposure to these elements via innovative packaging, as well as waterless delivery systems, can be beneficial when trying to maximize its shelf-life. 

 

Source:
DOI: 10.1111/j.1365-4632.2004.02134.x
DOI: 10.2310/7750.2008.07092
DOI: 10.1111/j.1473-2165.2011.00588.x
DOI: 10.1001/archotol.125.10.1091
DOI: 10.1046/j.1524-4725.2002.01129.x
DOI: 10.1034/j.1600-0625.2003.00008.x
DOI: 10.1016/j.jaad.2008.05.004
DOI: 10.1111/j.1473-2165.2008.00408.x
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