The importance of hydration

Firmness and resilience in the skin are synonymous with youth. These factors depend on the amount of water contained in the skin, or skin hydration

The skin holds 20% of the water in our bodies, and, of this 20%, 70% is contained in the dermis, the so-called "water tower" of the skin. From the deep layers of the dermis, where it is most abundant, water continuously rises to the layer above, the corneum. Here is where we "lose" water through aprocess both of evaporation and of perspiration (perspiratio sensibilis and perspiratio insensibilis).

Through these physiological mechanisms, the skins loses about 500 ml of water a day. The corneum layer creates a barrier that prevents more loss of water, using its multi-layer structure and working together with the hydro-lipid film, a protective, transparent cover surrounding the corneum. If it weren't for these, we would lose about 8 litres of water in 24 hours! The hydration and wellbeing of the skin depends on the amount of water present in the corneum layer. The corneum layer in young skin is 13% water and this level lowers to 7% with age. An American researcher has set 10% as the "critical threshold" of hydration, below which a change in the skin's texture and the properties of the hydro-lipid film give rise to the phenomenon of dry skin.

The phenomenon of dehydration constantly increases, because the hydrolipid film and corneum layer are worn down daily. Inevitably, their function as a barrier is diminished. The result of this decrease in protection is an excessive loss of water that affects the skin, making it rough, opaque and less elastic.

The enemies of skin hydration are the environmental factors that all of us experience on our skin: increased city living, excessive exposure to the sun's rays, the use of chemical cleansers that are often too harsh, hot water, and the frequent use of air conditioning and heating, as well as more personal factors such as anxiety and the stress of modern life. These are added to physiological aging, making the phenomenon of dry skin more important today than in the past, more diverse and more likely to become chronic.