Ending the Drought

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by Diana L. Howard, Ph.D.

Like other organs in the human body, water is the primary component of the skin. Over time and with physiological changes and exposure to the environment, we often find the moisture content of the skin declines resulting in dry skin. Dry skin can be so mild we hardly notice it or so severe it leads to a breakdown in the skin structure and integrity. It may manifest itself in many forms, from a dull, gray-white skin discoloration to dry, rough, scaly patches with cracks or fissures that can cause burning and stinging. When left untreated, the condition invariably worsens. As water continues to be lost from the skin, the skin deteriorates further with a loss of corneocyte cohesion causing increased cell detachment and scaling or flakiness. To the touch, the skin may feel rough with reduced elasticity. The latter is due to the fact that water helps maintain skin pliability and elasticity. Think of a dry kitchen sponge that is hard to the touch, with little elasticity. Once you wet that sponge it becomes extremely pliable enabling you to twist it into almost any shape you like.

What is Dry Skin?
When we look at a section of the epidermis and measure the water content through the different layers, we find that deeper layers (such as the stratum basale) have a higher concentration of water than the outermost layers. By the time we reach the outer stratum corneum layer, there is only about 10 percent of water remaining. When the water level drops below 10 percent, we end up with a dry skin condition. What causes the loss of water from our tissues? Intrinsic factors such as physiological disorders, illness, stress, etc. as well as extrinsic or environmental culprits are generally to blame. The latter category includes exposure to hot water, soap, chemicals (i.e. acetone), air conditioning, heating, frequent bathing, airplane travel, even friction from clothing, all of which can contribute to an increase in transepidermal water loss (TEWL) by compromising the skinÃ¢â‚¬â„¢s natural lipid barrier allowing excessive water loss. When the skin loses too much water, the outer layers may stiffen and develop fine cracks or fissures that become irritated or itchy; as you might expect this is exacerbated in areas of the body such as the arms, legs, and torso where there are fewer sebaceous glands present. Compounding the situation is the tendency for skin to dry more as we age; this is most likely due to a decrease in sebaceous gland activity and a slower recovery rate for lipids that comprise the barrier layer of the epidermis. Likewise, seasonal factors also exacerbate the situation; this is especially evident in fall and winter when humidity levels drop. Not only is the humidity level lower in winter, but exposure to indoor heat can aggravate the situation.

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As Vice President of Technical Development for The International Dermal Institute and Dermalogica, Dr. Diana Howard travels the world as a researcher and speaker, sharing her knowledge of ingredient technology, with a special emphasis on how ingredients impact the structure and function of skin. Dr. Howard earned her doctorate degree from The University of California Los Angeles where she specialized in plant biochemistry. For more than 29 years, Dr. HowardÃ¢â‚¬â„¢s interest in research on skin and the development of novel ingredient complexes has made her an invaluable asset to many of the major cosmetic companies. Today, she oversees all aspects of technical services for The International Dermal Institute which researches and develops the Dermalogica skin care line.