Topical Application: What are the dangers of ceramides?

The ceramides are a family of lipids naturally present in the skin, characterised by the combination of a fatty acid (saturated or monounsaturated), which may or may not be hydroxylated, with a sphingoid base via an amide bond. They account for 50% of the skin's composition.

They play a key role in the function of the epidermal barrier, where they constitute an essential component of the stratum corneum, the outermost layer of the skin. The role of ceramides is therefore to protect the skin from external aggressions and to prevent dehydration. Studies have even shown that a decrease in ceramide levels in the intercellular lipid lamellae of the stratum corneum is associated with a dry skin.

However, with age and sun damage among other things, the level of ceramides decreases, associated with a damaged skin barrier, fine lines, dry and rough skin, redness, a dull complexion, dehydration... Therefore, it is necessary to compensate for this deficiency with ceramide-rich treatments of natural or synthetic origin in order to strengthen the protective barrier of the epidermis.

As of now, ceramides are not classified as restricted-use ingredients in cosmetics by the United States (FDA), Canada (Health Canada), member countries of the European Union (EC) or South Korea (KFDA). Indeed, the use of ceramides is not subject to any restrictions and is considered safe in cosmetics in current practices of usage and concentration.

No skin reactions or systemic effects were observed during patch tests on animals or humans at repeated doses. Furthermore, although ceramides are lipophilic and likely to be absorbed by the skin, studies have shown that ceramides remain in the stratum corneum and do not penetrate any deeper.

Precautions to be taken?

• Origin: When ceramides are derived from the central nervous system of cattle (brain, spinal cord), they could pose a risk of transmitting infectious agents, such as bovine spongiform encephalopathy. The United States' "Food and Drug Administration" (FDA) and the European Union prohibit the use of ingredients derived from these tissues in cosmetic products.

• Tolerance: Before incorporating a new ceramide-based treatment into your routine, we recommend performing a tolerance test. This is done by applying a small amount of the treatment to the inside of your elbow, behind your ear, or on the inner side of your wrist. If you do not notice any adverse reaction within the next 24 hours, you can use the treatment.

• HELDRETH B. & al. Safety evaluation of ceramides when used in cosmetics. Cosmetic Ingredient Review (2015).

• LEE B-M. & al. Safety and risk assessment of ceramide 3 in cosmetic products. Food and Chemical Toxicology (2015).