Skin hydration is perceived mainly on the skin surface. If a skin lacks moisture, this has a very strong impact on its qualities including radiance, elasticity, youthfulness and comfort. Generally a well-hydrated skin appears younger as the ‘plumpness’ of the dermis and cells within the epidermis reduce the appearance of wrinkles.
Managing dehydration is therefore an essential element to be taken into consideration with cosmetic treatments.
Every skin type may one day or another be affected by dehydration. This can be a temporary and reversible condition, as dehydrated skin is not a skin type. Dehydrated skin is also not necessarily a dry skin as dehydration typically indicates a lack of water in the horny layer as apposed to a lack of lipids. A change in the hydrolipidic film can however cause a deficiency in water captors leading to trans-epidermal water loss (TEWL), and therefore dehydration. Normal to combination, oily, fragile capillary or sensitive skins may all lack water and suffer from dehydration.
Dehydrated skin presents with a slower metabolism and its protective barrier is altered. It is thus more fragile and can result in collagen and elastin degradation in the dermis. This means the skin’s ability to preserve its moisture levels declines and the stratum corneum quickly becomes dehydrated.
This can be seen or felt in several ways:
- Sensations of discomfort, tightness, lack of suppleness and elasticity.
- Appearance of dehydration wrinkles.
- Uneven skin texture which can no longer reflect light correctly, and lacks radiance.
- Roughness, flaking.
The result of all of this is accelerated ageing. The appearance of fine lines and wrinkles becomes more apparent.
The more dehydrated the skin is, the more obvious the wrinkles are.
Accelerating external factors:
- Climate conditions such as: cold, wind, sun exposure, hard water and air conditioned environments.
- Incorrect homecare: aggressive exfoliation, excessive peeling products, shaving or products containing alcohol.
Accelerating physiological factors:
- Ageing: the horny layer becomes dehydrated as the skin becomes thinner. Its water concentration declines from 13 to seven percent.
- Skin type: dry skin is the most susceptible to dehydration as a lack of lipids results in compromised intercellular cement and this leads to TEWL. This also includes those prone to dermatitis or psoriasis.
Water: where in the skin is water found?
Water follows a well-defined path through the different cutaneous layers. It is obtained primarily by diet and circulates as far as the dermis via a network of blood vessels. It then travels from the dermis towards the epidermis in order to maintain skin hydration.
Water in the skin is not evenly distributed. The cutaneous hydric gradient shows a gradual decline from 80 percent in the dermis, to 13-15 percent in the horny layer. 40 percent should be present at the border between the granular and horny layers and 70 percent in the viable epidermis.
The rate of stratum corneum hydration can drop rapidly in the presence of certain climate factors. The critical threshold is 10 percent.
“Dermal” water is essentially “non-mobile”, it is linked to dermal macromolecules known as glycosaminoglycan’s (GAGS) one of which is hyaluronic acid (HA).
“Epidermal” water moves by diffusion, travelling towards the surface of the skin and saturating the epidermal layers as it goes. The presence of water in the horny layer is necessary for the normal function of enzymes involved in corneocyte desquamation. The biochemical qualities of the skins extensibility, flexibility and resistance are due to the links made between the keratin fibres and water. This is aided by the natural moisturizing factor (NMF).
Water: How is it regulated?
The skin’s natural hydration is the result of two complementary phenomena:
- Static regulation: Barrier function.
- Dynamic regulation: Water flows from dermis to epidermis.
Static regulation: Barrier function
Hydric flows conclude with evaporation on the skins surface. For skin to be well hydrated, this evaporation must be perfectly controlled: the role of the epidermal barrier function must be in balance.
By reinforcing the lipid barrier, structural proteins and the NMF via an external supply and/or by stimulating the endogenous synthesis, it is possible to reduce TEWL.
- Natural moisturising factor (NMF) is able to maintain water on the skin surface acting like an ‘epidermal sponge’.
- Structural proteins these include filaggrin and keratin which help in structuring the corneocytes forming the horny layer of the skin, thus reinforcing the epidermal barrier function.
- Lipids those most involved in hydration are found in the upper levels of the skin. Sebum pairs with water to create a hydrolipidic film on the stratum corneum. Ceramides, fatty acids and cholesterol create the intercellular cement. A ‘hydrophobic barrier’ is created, preventing water loss.
Dynamic regulation: Water flows and cellular communication
The flow of water from the dermis to the epidermis is regulated by the skins cell structure and cell-to-cell communication. If these elements function correctly, the skin will be optimally hydrated.
This diffusion of water initially requires intercellular communication between the dermis and epidermis via the DEJ. Within the epidermis communication is carried out through the keratinocyte membranes, and water passes through two different paths:
• The peri-cellular path “around the cells” (1/3 of tissue water) involving tight junctions.
• The intracellular path “through the cells” (2/3 of the water is intracellular) involving aquaporins.
With age osmotic flows become irregular and some structures are deprived of the water they need.
• Hyaluronic acid (HA) has the ability to harness up to 1,000 times its weight in water making it an integral part of maintaining the skins moisture levels. It is also responsible for providing support, suppleness and anti-free radical properties within the dermal and epidermal architecture.
• Aquaporins are protein membrane channels that facilitate the passage of water through cellular membranes.
• Tight junctions semi-permeable links connecting one cell with its neighbours. They are located in the granular layer of the epidermis and prevent water rushing out through the intercellular spaces similar to how a canal operates. Tight junctions therefore play a vital role in keeping the skin barrier intact, regulating hydric flows and hydration of various layers of the epidermis.
Many hydrating products include exogenous ingredients such as emollients or humectants to deliver immediate hydration. The challenge to be met by cosmetologists involves not only delivering immediate hydration, but also guaranteeing long-lasting, high quality hydration. The objective to reach to ensure immediate, high quality and long-lasting hydration is practically unchanged: reinforce the barrier function and optimise hydric flows.
The various ways to manage this have evolved over the years and scientific progress now allows for unparalleled results in treating this condition.
The Sothys brand is reinventing the approach to the hydration issue in an innovative and exclusive way. Their advanced research team has made new discoveries on the patented 1055 Boletus Extract and have revealed its actions on dermal and epidermal hyaluronic acid! The active ingredients selected are derived from the most recent scientific breakthroughs in the fields of genomics (the study of gene action), proteomics (the study of proteins), lipodomics (the study of lipids) and glycobiology (the study of sugars).
The combination of the exclusive Sothys patented 1055 Boletus Extract with high molecular weight hyaluronic acid (HMW) and low molecular weight (LMW) effectively creates a Triple Hyaluronic Acid. This has a unique action on all components or key mechanisms involved in hydration: hyaluronic acid, NMF, tight junctions, aquaporins, intercellular cement lipids, structural proteins/filaggrin, intercellular communication and epidermal stem cells.
This provides the complete solution to the dehydrated skin concern.