What are the causes of dry skin?

The outermost horny layer of our skin (stratum corneum) plays the key role when it comes to storing moisture in the skin. It is basically made up from horny, non-viable skin cells (corneocytes) and fat-based substances (lipids). The lipids act like an adhesive, connecting the corneocytes to a  rm yet  exible layer – the surface of our skin. This physical phenomenon is often referred to as “brick and mortar model”. Apart from providing a protective shield for the subjacent skin layers and body, the stratum corneum retains naturally-occurring water and oil (sebum) in the skin, performing a barrier function.

What happens when healthy skin turns to dry skin?

A disrupted or lipid-de cient horny layer will allow water molecules from subjacent skin layers to evaporate away. This so called trans-epidermal water loss (TEWL) directly causes the skin to dry out.

What are natural moisturizing factors?

A second factor in this context are the so called natural moisturising factors = NMF. These substances (e.g. amino acids and lactic acids) attract and hold water molecules in the skin, thereby increasing the ability of the skin to bind and store water. Providing NMFs in a suitable formulation to the skin surface can be part of an effective therapy

against dry skin.

What are the external factors impacting the skin?

Apart from the physiological background, it is important to be aware of conditions that can cause or accelerate dehydration of the skin. These include: