Everything you need to know about Vitamin C.

Also known asascorbic acid, vitamin C is essential for the proper functioning of the metabolism but is not produced by it. It is crucial to supply it to the body through diet (citrus fruits, chestnuts, spinach, peppers, strawberries...) and/or dietary supplements. According to health authorities, to maintain good health, it is important to consume approximately 200 mg per day. Vitamin C is vital as it stimulates the immune system as well as tissue repair and contributes to bone development. Moreover, a prolonged deficiency in ascorbic acid (around 3 months) can lead to a deadly disease called "scurvy", characterised by a significant haemorrhagic syndrome.

Several studies concur that the epidermis is often deficient in vitamin C ; the reason being that only 1/3 of this molecule absorbed by the body is found in the skin. Moreover, when applied topically, vitamin C is much more effective for the skin than when it is ingested orally. Hence the success of cosmetic treatments formulated with this active ingredient.

In skincare, vitamin C is brimming with benefits; notably, it contributes to collagen production, brightens the complexion, and protects the skin from damage caused by sun exposure and harmful free radicals. Thus, this powerful antioxidant is found in many serums, facial cleansers, oils, and moisturisers. It also has excellent virtues for hair.

Pure Vitamin C, also known as L-ascorbic acid, is the one that provides the best results in terms of overall skin and complexion improvement. However, its acidic pH of around 3.5 must be maintained in a cosmetic formula to avoid oxidation issues.

This parameter can be restrictive, hence certain derivatives of Vitamin C are utilised such as "Magnesium Ascorbyl Phosphate", "Sodium Ascorbyl Phosphate", "Ascorbyl Palmitate", "Tetrahexyldecyl Palmitate", "Ascorbyl Glucoside" and even "3-O Ethyl Ascorbate".

When applied topically, vitamin C is far more effective than when ingested through diet.

• Antioxidant, it slows down skin ageing. By acting at the epidermis level, it strengthens the skin barrier and neutralises free radicals generated by pollution, stress or sun exposure;

• It enhances the appearance of the dermis and epidermis by regulating excess melanin for a visibly luminous complexion;

• She boosts the production of keratinocytes in order to optimise the skin's elasticity and minimise the pores;

• She reduces wrinkles by combating cell inflammation and by increasing the density of the dermal papillae;

• She hasimproved blood circulation and skin oxygenation to give a boost to the healing process and cellular renewal.

• It assists in reducing and preventing under-eye circles by strengthening the skin, which is generally thinner in this area of the face. Its action conceals the underlying blood vessels, helping to visibly diminish puffiness.

• It accelerates the production of collagen, which is responsible for the firmness and elasticity of the skin.

Vitamin C is generally safe when consumed in foods or applied topically. However, individuals with sensitive skin or allergies may experience a yellowish discolouration. This phenomenon is particularly noticeable on dry, dehydrated or sensitive skin, which tends to react poorly to acidic pH levels. Although rare, these individuals may experience irritations such as tingling, itching, and dryness after using vitamin C in skincare. This issue can be addressed by layering a moisturiser over the vitamin C treatment you are using. If you have sensitive skin, it is recommended to start with a low concentration of vitamin C to monitor any potential skin reactions. In all cases, it is important to test vitamin C before incorporating it into your daily beauty routine.

• OHSGIMA H. & al. Effects of vitamin C on dark circles of the lower eyelids: quantitative evaluation using image analysis and echogram. Skin Research and Technology (2009).

• TELANG P. S. Vitamin C in dermatology. Indian Dermatology Online Journal (2013).