|Definition of Dehydrated Skin|
Surface dehydration is a crippling enemy of the skin affecting up to 98% of the populations in varying degrees, and is associated with problems as diverse as scaly, taut skin, superficial lines and premature aging. Given the singular importance of dehydration, it is necessary to understand the function of the skin in order to treat it properly. How the skin is moiturized, how water is lost from the horny layer, and ways to prevent water loss.
|How the Skin is Moisturized|
Interstitial (between cells) fluid reaches all body tissues through the blood, and makes up approximately 70 % of the body. It penetrates capillaries and circulates within and among cells, carrying with it nutrients and water vital to cellular function. It then acts as a waste collector for the cells and eventually becomes lymph, flowing back through the lymph vessels with the accumulated wastes. Without this proper exchange of nutrients, water and wastes, cells cease to function and eventually die.
Although sufficient water intake is critical in maintaining metabolism, it will not by itself correct existing surface dehydration. The main water reservoir of the skin is located in the two lower layers, the dermis and hypodermis, and is regulated by the antidiuretic hormone (APH) secreted by the pituitary gland. The epidermis, the location most vulnerable to fluid deprivation, cannot compensate by drawing moisture from below, as interstitial circulation ceases where epidermal cells become keratinized. The epidermis can receive moisture indirectly only by the production and upward movement of new cells (containing adequate amounts of fluid) from below, or topical moisturizing of the horny layer.
The purpose of sebum, a hydrophilic fat, is to mix with water from the atmosphere and secretions from the sudoriferous glands and form the hydro-lipid film, which ensures cohesion and flexibility of the horny layer. The constituents of this film, and its slightly acid pH, create an ideal surface ecology that is vital for skin health and beauty.
|Causes of Surface Dehydration |
The horny layer provides the clue to surface dehydration. Since one of the major functions of the skin is to provide a barrier against moisture infiltration, and because hydrophobic fats in the horny layer constitute this barrier, wetting the epidermis does not allow moisture into the skin. The horny layer, then, prevents transfer in both directions. Surface dehydration can occur for several reasons:
A) Poor cleansing: Any cleanser leaving the skin "squeaky clean" or even taut is dehydrating. Soap is harsh because it is alkaline, stripping the hydro-lipid film from the surface of the epidermis and leaving the horny layer exposed, unprotected and subject to moisture loss. Other alkaline washes, such as foaming cleansers and alcohol solutions used for oily and problem skin, are even worse since they produce closed comedones (clogging) which ultimately become blackheads and possible pustules.
B) Skin damage: This may result from using harsh acne treatments like hydrogen peroxide, retinoic acid, benzoyl peroxide, hexachlorophene, etc. These substances alter the keratinization process and weaken the ability of the cells in the horny layer to bond together. A similar process results from continual sun exposure, and in addition dermal tissues which affect the transfer of moisture to the epidermis break down and do not function properly. In both instances the damaged skin takes on a withered look, and affected persons need assistance at the level of the horny layer.
C) Neglect: This covers a wide area, from failure to drink sufficient amounts of fluid, to applying protective creams on a regular basis, to deliberately hampering the body's ability to function normally. Cigarette smoking, for example, is directly associated with wrinkle formation by constricting blood flow in the capillaries, which reduces the flow of moisture and nutrition to the cells.
D) Medication and illness: Certain illnesses may cause internal dehydration and ultimately affect the epidermis. Diuretics and many cold and flu remedies that dry up mucous have their side-effects on the skin's surface. The use of cortisone also induces dehydration and may produce permanent effects since it acts in the dermal layer.
E) Inadequate moisturizers: Light textured and milky moisturizers that "disappear" into the skin offer little or no protection. The water soon evaporates and does not penetrate the horny layer due to the presence of hydrophobic fats and the "Electro-Physical Barrier of Rein". The superficial wetting only impregnates squamous cells, and the constant evaporation of water can itself cause severe dehydration and fissures to form in the horny layer.
F) Scrubs: The regular use of scrubs can break down cell cohesion in certain skin types, which reduces the capacity to retain moisture and places capillaries at risk.
G) Astringents: Alcohol based tonics wiped on skin remove sebum and act like strong cleansers. Use toners only on dry, sallow skin that does not show couperose tendencies, and pat them on following application of a day protective or lipid cleanser.
H) Air conditioning and climate: Moisture evaporates quickly within the dry atmosphere of air conditioned and/or overheated rooms, and adequate protection must be taken. Similar precautions are necessary in very hot or cold climates.
I) Hot showers: The friction and heat of hot water remove sebum from the skin's surface, inviting capillary damage and dehydration. Always wash the face separately using lukewarm water only.
J) Diet: An excessive intake of table salt (sodium chloride) can have a dehydrating effect. It transfers water from the interior of the cell to the interstitial fluid, creating water retention and bloating at the same time. Coffee, in addition to other negative effects, can also contribute to dehydration.
|Steps to Reduce Moisture Loss |
Identifying the causes of dehydration then see if corrective action is possible. Additionally, several types of protective products or moisturizers should be considered carefully, since they may be useless or harmful.
A) Oil-in-water (o/w) emulsions with a high water content: tend to evaporate easily and may accelerate dehydration by drying the epidermal surface. These products are generally sold over the counter in drugstores and department stores and should not be recommended if dehydration is evident.
B) Oil-in-water emulsions containing natural moisturizing factors (NMF): such as amino acids, glucose or electrolytes, are better as they help to retain moisture on the skin's surface. They are insufficient, however, if used under harsh climatic conditions (hot or cold dry winds, for example).
C) Protective creams with a high lipid content: are the true protectives. They are chemically similar to the skin's own surface film and only small quantities need to be patted on (not massaged in). Inferior creams must be avoided, though, because their low quality raw materials may be comedogenic and cause harm, particularly on oily skin.
D) Humectants containing glycerin or sorbitol: may be adequate in many instances. Caution must be exercised because they attract moisture indiscriminately and under certain conditions may draw water from lower skin layers. They should not be used by individuals already suffering from dehydration, or living in a dry climate.