Clive Anderson - AT THE DERMATOLOGIST NORMAL HEALTHY skin is the body's first line of defence. It is a seamless physical barrier to micro-organisms - bacteria, viruses and fungi, and it prevents the entry of harmful substances into the body.
The natural resistance of the skin is as a result of several factors. These are:
A horny outer layer of cells which is impermeable to chemicals and bacteria. The continuous shedding of these cells carrying the bacteria and other harmful substances with them off the body
The natural acidity of the skin (pH 5.5) changes in any of these factors can increase the likelyhood of micro-organisms and toxins breaching the skin barrier and affecting the body.
Unfortunately, our daily cleansing often results in disruption of the skin barrier. The acid mantle a fine film of slightly acidic pH on the skin surface plays an important role in the barrier function of the skin. The acid mantle provides indirect protection against invasion by micro-organisms and direct protection against alkaline substances.
If the acid mantle is disrupted or loses its acidity the skin becomes more prone to damage and infection. Once damage has occurred it can take up to 14 hours to restore and repeated frequent washing often exacerbates the damage. Some of the cleansing agents most often used result in a loss of the acidity of the skin and increase irritation and infection. There are three main categories of cleansing agents:
Soap made by combining a fat source (either animal or vegetable) and an alkali. This results in an alkaline product and most soaps have a pH of 9.5 - 10.5, for example:
Camay - pH 9.5
Dial - 9.5
Irish Spring - 9.5
Palmolive - 10.0
Zest - 10.0
Dove is mild soap with a pH of 7
Soaps make the skin more alkaline than do synthetic bars. A single wash with soap can shift the pH balance to the alkaline region hence disrupting the acid mantle of the skin and increasing the propensity for infection and irritation. It is even more important for persons with skin conditions such as Atopic eczema, acne, rosacea and dry sensitive skin to avoid alkaline soaps (pH above 7) and use instead a mild cleansing agent.
Indeed some studies have shown an increase in acne causing bacteria on the skin with the use of soaps and a decrease when the synthetic detergents are used.
Synthetic detergent bars (syndets) are composed of synthetic detergents and contain less than 10% soap. They have an adjusted ph of 5.5 - 7 E.g. Cetaphil, Neutrogena, Aveeno, Basis, Oilatum. The synthetic detergents provide a product that is less irritating to the skin. Commonly used detergents in bar type cleansers are sodium tallowate, sodium palmitate and sodium state. In liquid formulations sodium laureth sulfate lauremide DEA, and sodium cocyl isethionate are commonly used. These products have a pH that is closer to that of healthy skin. Body washes are a special subset of liquid synthetic detergents that combine a mild skin cleanser with a moisturiser to improve skin hydration.
Lipid - free cleansers
Lipid free cleansers are liquid products that clean without fats. These products contain water, glycerine, cetyl alcohol and occasionally propylene glycol. They leave behind a thin moisturising film and can be used to remove cosmetics.
Dr. Clive Anderson is a dermatologist
