In medicine, the definition of the term acid mantle is disputed because a large number of pathogenic bacteria also feel comfortable in an acidic environment and can multiply there. This concept is mainly used by manufacturers of supposedly “pH friendly” personal care products for product differentiation.

The skin’s protective mechanism produces sweat and fat throughout the day . Sweat contains organic acids and sebum fatty acids . These two “helpers” regulate the pH value in a range between 4 and 6. Since this protective function is distributed over the entire body like a coat and is located in the acidic pH environment, the definition is self-explanatory. The medical specialties are dermatology and physiology.

function & task

The skin is the largest and therefore the most important human sensory organ . It protects our body and serves as a contact surface to our environment. Healthy skin has an effective protective acid mantle that protects the human organism as a barrier against the penetration of pathogens such as viruses , bacteria , fungi , allergens and chemical substances. The protective skin layer ensures a balanced moisture balance and protects against external environmental influences such as heat, cold and injuries. 

The skin is a sensory organ that enables people to perceive sensations such as heat, cold, pressure and pain through touch. The skin barrier in the form of the protective acid mantle is one of the most important components of the human skin and is closely connected to the cornea . It is similar to a wall structure in which several layers of horny cells are held together by epidermal lipids (horny fat). The denser this bond is, the more resistant the skin is.

The skin’s protective layer consists of a thin film of fat and water covering the horny layer. It consists of parts of the horny cells as well as sweat and sebum. Due to perspiration, the environment of the protective acid mantle is slightly acidic. This prerequisite is ideal for the balanced bacterial balance of a healthy skin flora. Undesirable and harmful foreign germs in the form of bacteria, viruses, fungi and other microorganisms cannot multiply and penetrate the body if the protective acid mantle is intact.

The protective acid mantle protects against alkaline substances and foreign germs. Without an acidic environment, the pH value would rise to 9 or 10 and develop into an ideal breeding ground for foreign germs, as they feel very comfortable in an alkaline environment.

However, physicians assume that the protective function of the acid mantle is not exclusively due to a low pH value, but is due to the interaction of several secretions secreted by the skin glands. The protective film of the skin created by the sebum and sweat glands contains water as its main component. Other ingredients are uric acid , urea , bactericidal peptides , electrolytesand fatty acids. This interaction forms an ideal synergy to prevent the growth and reproduction of non-resident microorganisms in the form of a chemical barrier. The fats secreted by the sebaceous glands are stored in the horny layer of the skin and make it supple and water-repellent.

Diseases & Ailments

When medicine talks about the pH value of human skin, it means the thin layer of moisture on the skin, which consists of sebum and sweat, which forms the protective acid mantle with a pH value between 4 and 6. This value indicates that the skin’s protective film has a slightly acidic environment in which a large number of beneficial bacteria thrive. 

This value can change with the reduction or increase in perspiration on the skin. This change depends on how a person eats , how much exercise they do, whether they exercise or take medication. Perspiration is therefore largely involved in the formation of this protective mechanism.

The unpleasant odor associated with sweating is caused by the breakdown of skin bacteria. The pH value and thus the protective acid mantle react with short-term changes when people clean their skin with soap or use cosmetics . These products contain alkaline substances that help remove the fatty layer of sebum on the skin. After a shower, the skin feels clean and fresh, but in reality part of the protective acid mantle in the form of the skin’s natural oils has been removed. This is also due to the fact that water has a pH value of 7 and also attacks the acid mantle when showering. In addition, with these cleansing products, the natural skin flora in the form of beneficialRemoves lactic acid producing bacteria important for pH stabilization.

Most manufacturers of cosmetics and care products like to advertise that their products are pH-neutral or even help to restore this value. However, this statement is a marketing strategy of the advertising industry. These supposedly acidic or pH-neutral products contain surfactants that remove from the skin what is actually supposed to protect it: the sebum and oil film in the form of the protective acid mantle. This makes the skin more susceptible to the side effects of creams, soaps and other personal care products.

If the protective acid mantle is severely disturbed and the pH value is out of balance, allergies , skin irritations, skin impurities, eczema , abscesses and inflammation can form on this basis. Although a healthy skin flora restores an imbalanced pH value and a protective acid mantle within a few hours, care should be taken during body care not to stress the skin by cleaning it too vigorously. Hygiene would then be counterproductive.