Three products for a radiant, customizable tan — without UV rays

Three products for a radiant, customizable tan — without UV rays

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Temps effets vitamine C.

How long does it take to see the results from using products containing Vitamin C?

Summary
Published February 20, 2024, by Stéphanie, Doctorate in Life and Health Sciences — 5 min read

The vitamin C (INCI name: Ascorbic Acid) is a water-soluble antioxidant suitable for all skin types. Used for many years in skincare formulas, it is recognized for its various benefits.

  • Antioxidant : It protects cells from oxidative damage caused, among other things, by UV rays by eliminating free radicals and reactive oxygen species. Oxidative stress and the damage it causes can lead to premature aging and pigmentation, and can also damage the DNA of cells.

  • Brightening : By inhibiting melanogenesis, vitamin C can help fade brown spots visible with its anti-tyrosinase effect. It also stimulates blood flow through the endothelial production of nitric oxide (NO) by increasing the chemical stability of tetrahydrobiopterin, a cofactor of constitutive NO synthase, resulting in an increase in its half-life in aqueous solution. Thus, this activity of vitamin C helps to restore radiance and brightness to the skin. As a reminder, a dull complexion can be related to poor blood circulation, associated with poor cell renewal.

  • Moisturizer: Recent studies have reported new functions for Vitamin C: it is suggested to contribute to the formation of the epidermal barrier by enhancing epidermal differentiation and stimulating the production of sphingolipids.

  • Firming : Vitamin C also accelerates the production of collagen and elastin, which help to keep the skin firm, elastic, and bouncy. It has been shown that ascorbic acid acts on dermal fibroblasts to stimulate the synthesis of collagen and elastin, being necessary for the enzymatic activity of prolyl hydroxylase (procollagen-proline dioxygenase) for the formation of hydroxyproline by hydroxylation of proline residues in procollagen and elastin. Indeed, hydroxyproline represents about 25 to 30% of the total amino acids of these proteins. It also has an effect on the stabilization of collagen fibers and the reduction of their degradation.

How long does it take for Vitamin C to work?

  • After 4 months of daily use, the skin's complexion is improved. In other words, pigmentation flaws are diminished and the skin regains its uniformity. For instance, ESPINAL-PEREZ & al. (2004) examined the depigmentation effect of topical ascorbic acid on the facial skin of 16 patients suffering from melasma over a period of 16 weeks (4 months). They conducted a comparative study: the patients were required to apply a 5% vitamin C emulsion on one side of their face and a 4% hydroquinone emulsion on the other side of their face. As a reminder, hydroquinone is known for its skin whitening effect. The researchers compared the pigmentation changes on the sites where vitamin C was applied with those on the hydroquinone sites. Ascorbic acid showed a lightening effect similar to that of hydroquinone on the hyperpigmented areas of the skin.

  • After 3 to 6 months of daily application, benefits are visible in terms of skin aging. The ability of vitamin C to synthesize collagen and protect against UV-induced oxidative damage has been examined in clinical studies on volunteers over a 6-month period. An oil-in-water emulsion containing 5% vitamin C was applied once a day to the sun-exposed skin of the lower neck and forearm, while a control formulation without ascorbic acid was applied to the other side. This led to a statistically significant reduction in clinical signs of photoaging compared to a placebo formulation. Indeed, biopsies performed on the "treated" sites revealed an increase in type I and III collagen mRNA, as well as mRNA of three extracellular procollagen transforming enzymes on the "treated" sites with ascorbic acid compared to the control.

This progression depends on the concentration of vitamin C in the skincare product and the frequency of application. Similarly, everyone's skin improves at a different pace: some may see immediate results, while others may have to wait longer. Regarding the derivatives of vitamin C, almost the same time frame is observed.

Sources

  • LAPIERE C. M. & al. Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue 1 inhibitor of matrix metalloproteinase 1 in the human dermis. The Society for Investigative Dermatology (2001).

  • ZAHOUANI H. & al. Topical ascorbic acid on photoaged skin. Clinical, topographical and ultrastructural evaluation/ double-blind study vs. placebo. Experimental Dermatology  (2003).

  • CASTANEDO-CAZARES J. P. & al. A double-blind randomized trial of 5% ascorbic acid vs 4% hydroquinone in melasma. International Journal of Dermatology (2004).

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