Acid Mantle and pH of Skin
The acid mantle is a thin oily film that sits on top of the outmost layer of our skin. For most people, the pH of the acid mantle is about 4.5 to 5.5. Why is our skin naturally acidic at the surface? Our slightly acidic skin helps to fight off harmful bacteria. Many of the contaminants that might enter our skin, such as chemicals from the atmosphere and harmful bacteria, are alkaline in nature (i.e., they have a pH of higher than 7). Our skin’s natural acidity neutralizes these chemicals and bacteria, much the same way the milk of magnesia neutralizes stomach acid when we have heartburn. Neutralizing these harmful contaminants is part of the body’s defense system. Maintaining the skin pH at the proper level is vital to protecting ourselves from harmful bacteria which can lead to acne, infection, or irritation.
The term pH stands for the “potential of Hydrogen”. It is a measure of the Hydrogen ion concentration of a substance. The Hydrogen ion concentration is more commonly referred to as the acidity or alkalinity level. The more acidity in the substance, the lower the pH, the less acidity, the higher the pH. There are differing values of pH in the body depending on what function is being performed. For example, the pH of the stomach is very acidic, around 1, because stomach acids help break down the foods we eat. Our saliva and blood, on the other hand, are much closer to neutral. Neutral substances, like water, have a pH of 7. A pH above 7 is considered alkaline (less acidic), and a pH below 7 is considered acidic.
Most of us use soap and water to clean our faces without realizing that this may not be beneficial to us. Soapy water is highly alkaline (with a pH of 12, see chart) while our skin is naturally acidic (with a pH of approximately 5). Soapy water is commonly used to clean our faces because it removes the natural oils from the skin. While this leaves our skin with that “clean feeling,” soap is actually neutralizing our skins acid pH thereby stripping away our natural defense systems. Particularly for those of us that wash our faces 2, 3, or 4 times a day because of a problem condition like acne, stripping away the acid mantle can actually worsen our condition. Similarly it is important for us to know the pH of any cleansers, moisturizers, makeup and other products we use so that we don’t remove the protective oils and acid mantle from our skin.