The various forms of Vitamin C.

The vitamin C in its pure form, also known asL-ascorbic acid (INCI name: Ascorbic Acid), appears as yellowish crystals or powder. This type of ascorbic acid is the most well-known of all and allows for excellent results in terms of overall skin and complexion improvement. However, its acidic pH around 3.5 must be maintained to avoid oxidation problems. Indeed, unstable vitamin C can have effects contrary to those originally sought and promote the formation of free radicals, causing oxidative damage to skin cells and accelerating their overall ageing.

However, reducing the pH of a cosmetic formula can lead to skin sensitisation, as the natural pH of the skin is around 5.5 - 6. To incorporate vitamin C into a cosmetic formula that respects the skin's pH, certain derivatives exist. Even though their effectiveness cannot be compared to that of pure L-ascorbic acid, they still provide relevant benefits to the skin, particularly for brightening dull complexions and combating signs of ageing.

Generally, these derivatives are combinations of ascorbate (vitamin C in a non-acidic form) with alkalising minerals (calcium, magnesium, sodium, etc...). Here are examples of vitamin C derivatives frequently used in the formulation of skincare products:

• The sodium ascorbyl phosphate (INCI name: "Sodium Ascorbyl Phosphate"):

  This refers to a water-soluble form of pure Vitamin C, which is much more stable against oxidation. It is particularly interesting and widespread in skincare because it has the ability to transform into ascorbic acid once applied to the skin. This form of Vitamin C also has the advantage of being less irritating, making it more suitable for sensitive and atopic skin.

• The Magnesium Ascorbyl Phosphate (INCI name: "Magnesium Ascorbyl Phosphate"):

  This is one of the most stable forms of vitamin C. However, a study conducted by the Duke University Medical Center found that this substitute did not increase the natural levels of vitamin C in the skin.

• Thetetraisopalmitateofascorbyl (INCI name: "Ascorbyl Tetra Isopalmitate"):

  This is a oil derived from pure L-ascorbic acid ; it easily penetrates the skin and can be used topically at high concentrations without risk.

Furthermore, there are other derivatives of vitamin C in skincare, whose I.N.C.I. names are "Ascorbyl Palmitate", "Tetrahexyldecyl Ascorbate", "Ascorbyl Glucoside" and "3-O Ethyl Ascorbate".

The ascorbyl tetraisopalmitate is present within the tinted serum. Formulated without nanoparticles and without silicones , the tinted serum is composed of 99% naturally derived ingredients. It provides light coverage and evens out the complexion. Each tinted serum can correspond to a wide spectrum of skin tones. The six shades of the serums have been developed according to the FITZPATRICK phototype scale.

The sodium ascorbyl phosphate is the active derivative of Vitamin C present in the following four treatments:

• Radiance Tonic :

  Enriched with active ingredients to balance the skin's pH, brighten the complexion, and reduce the appearance of pigmentation spots, this toner also contains lemon verbena water that imparts a slight fruity scent. After the stages of makeup removal and skin cleansing, soak a cotton pad with the radiance lotion and apply it all over your face, avoiding the eye contour, morning and evening. Do not rinse. You can then apply your daily serum and day cream.

Note : The radiance lotion may naturally yellow over time, but this does not affect its effectiveness.

• Radiance Serum :

  This is a treatment that boosts radiance and helps you combat dull complexion. Morning and evening, apply 3 to 4 drops of this serum on a previously cleansed and dried face. Gently massage the skin with circular movements. Then apply a moisturising cream suitable for your skin type. We recommend using your vitamin C serum for at least 4 weeks to see its effects.

Note :This vitamin C serum naturally yellows over time. This effect does not diminish the product's effectiveness.

• Firming & Radiance Complex with 5 Vitamins :

  This is a gelified aqueous serum concentrated with antioxidant actives. This skincare product provides both preventive and corrective action against the appearance of ageing signs. The epidermis is toned, the complexion even and luminous.

• Antioxidant Face Cream :

  Less concentrated in vitamin C than the serum, the face cream can be a good alternative for sensitive skin. Like the serum, it fights against free radicals, prevents the appearance of fine lines and gives a glow to the skin. We advise you to apply a small amount morning and evening on the face previously cleaned and dried, after your usual serum. Then, gently massage in circular motions to perfect the cream's penetration through the skin.

• Wrinkle and firmness loss serum:

  Comprised of 99% natural ingredients, this skincare product contains plant-based collagen (1%) and vitamin C (10%). The hydrolysed plant collagen, known in the I.N.C.I. as " Cocoyl Hydrolyzed Collagen/Collagen Amino Acids" is a biotechnological active ingredient that mimics type I human collagen. It works in synergy with vitamin C to stimulate fibroblasts, which produce collagen fibres, thereby reducing the depth of wrinkles.

• CHIANG N. & al. Topical vitamin C and the skin: Mechanisms of action and clinical applications. Journal of Clinical and Aesthetic Dermatology (2017).

• VISSERS M. C. M. & al. The role of vitamin C in skin health. Nutrients (2017).