Since 90% of the skin is impermeable, we can't deeply moisturize it by draining it of water. For proper hydration, you need to supply water to the various epidermal layers, ensuring that the skin can retain it and prevent it from evaporating too quickly. The degree of water impregnation depends partly on the moisture in the deeper layers, but mainly on the amount of perspiration released by the sweat glands at the surface, and also on the ambient atmosphere. Water in the skin evaporates if the air is dry. Superficial dehydration of the skin is characterized by slight exfoliation, and is often associated with skin that also lacks oil. Lack of water deep down causes skin to look dull, flabby, withered and sometimes parchment-like. All skin types can suffer from dehydration, even oily and combination skins, and is characterized by a rough, powdery appearance, highly visible on the surface.
Water is essential for the proper functioning and renewal of epidermal cells. The superficial cells of the stratum corneum are responsible for the skin's appearance and texture. When skin is dehydrated, its quality is altered, and it typically becomes rough, dull and lacking in suppleness. Under these conditions, dehydrated skin is more susceptible to the passage of potentially toxic or allergenic substances. It is therefore more sensitive and reactive. All skin types, even oily skin, can be dehydrated.
Causes of skin dehydration
- The environment: heat, dry air and wind aggravate water loss due to evaporation. Conversely, a humid environment reduces water loss.
- Unsuitable skin care: the use of cleansers containing harsh chemical soaps that are not offset by a high-quality natural cream. Frequent cleansing and exfoliation alter the hydrolipidic film.
- Aging: the main factor aggravating cutaneous dehydration is the reduction in sebum production with age and menopause.
- An unbalanced diet: lack of oils rich in fatty acids.
The natural regulation of skin hydration
Water is constantly supplied to the skin by blood circulation in the dermis, then by diffusion to the epidermis, hence the importance of drinking enough water every day. Also, the skin is unable to draw water from the outside. At the same time, water is continually lost through perspiration and evaporation. Hydration of the epidermis therefore depends on the balance between water loss and supply. The lipid cement, the cell membrane and the hydrolipidic film slow down water evaporation, and this is what we call the « cutaneous barrier ».
Replacement elements in cosmetics
As the skin is almost impermeable to external water, only a small quantity is able to penetrate between the dead cells in the desquamation phase.
In cosmetics, moisturizing products work by reproducing the skin's natural functions. They reduce water loss by counteracting evaporation through film-forming and/or emollient agents, and humectants which, like tiny sponges, retain and draw water from the dermis into the cells. Humectants have a deeper action. Emollient agents smooth, soften and protect the skin's surface by filling the micro-cracks that form between the cells of the epidermis' superficial layers.
Natural moisturizing cosmetic ingredients
Many natural ingredients are treasures for our skin. Film-forming, emollient and humectant ingredients play complementary roles.
Every day
Skin hydration is closely linked to the hydration of the body itself. With this in mind, we recommend drinking 1.5 liters of water a day. Dry, dehydrated skin can also be the result of a dietary imbalance. Try consuming raw, organic, first cold-pressed oils rich in unsaturated fats, or including in your diet a one- or two-month supply of borage, evening primrose or other omega capsules. As water loss is permanent, the skin needs to be moisturized morning and night. Choose a skincare product suited to your skin type.