What you need to know about ceramides.

Ceramides belong to a heterogeneous class of lipids found in the stratum corneum, the outermost layer of the epidermis. They were first described and characterised in the early 80s by researchers WERTZ and DOWNING, followed by Peter ELIAS. Today, 11 classes of ceramides have been identified.

Structurally, ceramides are sphingolipids : the fatty acid is linked to sphingosine by an amide bond. Ceramides are in cohesion with other lipids such as cholesterol and form a highly ordered lamellar structure known as skin barrier. This barrier helps to limit transepidermal water loss, also known as insensible water loss. In other words, it is essential for maintaining a good level of skin hydration and protecting the skin from external aggressions. A decrease in ceramide content or a change in their chemical structures can lead to various skin disorders.

In cosmetics, ceramides are increasingly being used in the formulation of various skincare products. They can be of synthetic or plant-based origin.

Ceramides are renowned skin care agents for the following two properties:

• Strengthening the skin barrier and preventing dehydration.

  Ceramides have molecular structures similar to certain lipids found in the corneal layer; these molecules are thus described as biomimetic and are very well tolerated by the epidermis. They easily integrate into the natural lipid barrier to strengthen its protective action and reduce transepidermal water loss.

• Normalise the natural desquamation process of the skin.

  Type VI ceramides are also alpha-hydroxy acids (AHA). They therefore have an exfoliating action and stimulate cellular renewal, resulting in a smoothed skin texture and unclogged pores.

In the field of hair care, ceramides are also increasingly favoured. The lipids of the hair cuticle and cortex are degraded due to the numerous aggressions suffered by the hair (colouring, shampooing, brushing...) and cannot be naturally replaced. Ceramides, due to their biomimetic nature, insert themselves into the lipid cement of the hair fibre and restore the cohesion of the cuticle. The flaws, also called "scales", are filled, the cuticle is smoothed and the cortex is better protected. The split ends are thus filled, the hair is less brittle, smoother and shinier.

In relation to the scalp, ceramides strengthen the skin barrier, thus combating dehydration, thereby preventing the onset of itching and dandruff.

Whether derived from plant or synthetic sources, this active ingredient has no contraindications. Ceramides are recognised for their safety and excellent skin tolerance. Therefore, they can be applied to all skin types, even the most sensitive ones.

In topical application, ceramides are found in facial sheet masks, restorative creams, protective winter creams for hands, feet and face, as well as in shower gels. In terms of hair care, ceramides can be found in protective shampoos and conditioners, fortifying restorative treatments, balms and masks, as well as in styling products for curly, frizzy, straightened hair, and so on.

Typology has developed two treatments based on plant-derived ceramides obtained through biotechnology:

• The hair mask restorative with 0.3% biomimetic ceramides and avocado oil to deeply repair and nourish the hair fibre, smooth and soften the hair, and prevent the appearance of split ends.

• The Dryness & Blemishes Serum with 1% ceramides and lavender extract to repair the skin barrier and reduce skin eruptions.

• DOWNING D.T. & al. Ceramides of pig epidermis: structure determination. Journal of Lipid Research (1983).

• ELIAS P. M. Epidermal lipids, barrier function, and desquamation.,Journal of Investigative Dermatology. (1983).