A century ago, Schade and Marchionini first coined the term Säuremantel or “acid mantle” to describe the acidic nature of the skin. In the last decade, the acidity of the skin has gained prominence as an important aspect of the skin’s health and appearance, as the disturbance of the delicate pH of the skin is associated with a myriad of skin problems. These skin abnormalities are the result of inflammageing (inflammation ageing) of the skin, which are in turn directly attributable to an altered skin pH.
Not knowing just how important it is to maintain an acidic environment on the skin is evident in the scarcity of low pH soaps, cleansers, and moisturizers. The purpose of this blog is to help you understand the importance of the “acid mantle” and provide you with objective evidence that skin pH is linked to the health and appearance of your skin.
Abnormal pH is a key factor in many skin diseases. We will give practical recommendations on what key elements you should look for in selecting products to use that preserve the acid mantle. At the very least, we hope to provide some “pH” food for thought!
What is pH?
pH actually stands for “potential of hydrogen” and tells us how much hydrogen is present in liquids and how active that hydrogen is. That being said, pH is a measure of how acidic or alkaline something, usually water, is. The range goes from 0 to 14, with 7 being neutral. A pH of less than 7 indicates acidity, whereas a pH of greater than 7 indicates an alkaline solution, which is also called a base. The normal skin pH is acidic, ranging in pH values of between 4.0 and 6.0, while the body’s internal pH is near-neutral or slightly alkaline (between pH 7.0 and 8.0). This creates a pH difference of 2 to 3 units between the skin and the body.
The skin's surface pH is slightly above 7 immediately after birth but decreases steeply in the first few days, until later in infancy it is like that of adults, settling down between pH 5 and 5.5.
Diseases of the skin associated with altered pH-values
An example of an area where pH plays a role in maintaining health is in the armpit (axilla). Higher pH levels in the axilla lead to the growth of odour-producing bacteria such as Cutibacterium acnes responsible for acne, and staphylococci, which is responsible for boils. Deodorants containing citrates lower the pH, and this inhibits bacterial growth which prevents acne or boils from occurring in the axilla. Alkaline skin pH likewise causes fungal infections. An example of an alkaline skin environment that causes candida infection is in the skin fold areas of the groin.
A higher pH, or alkaline skin, also creates a disturbed barrier linked to atopic dermatitis (AD). Conversely, lowering the pH in AD in turn leads to a reduced inflammatory response, which then improves the AD. In a study of 100 children with AD, pH was observed to be significantly higher in eczematous skin in comparison to the skin of 21 healthy children. These findings provide exciting possibilities about the use of acidic topical skin products in altering the course of inflammatory skin diseases.
Conversely, lower pH levels or acidic skins are associated with improved skin barrier function and skin health. When we compare ethnic skin (pH 4.6) to Caucasian skin (pH 5.0), ethnic skin usually has a better barrier function due to its more acidic nature. When lowering the pH in Caucasian skin to levels like those of ethnic skin the Caucasian skin demonstrates an improved barrier function, on par with that of ethnic skin.
The pH of the skin plays a role in the development of the inflammatory condition better known as nappy rash. Other factors, including prolonged exposure to urine and faeces, change the skin’s biome which contributes to nappy rash. There is a significant correlation between the severity of the nappy rash and an elevated skin pH in the diaper area - the higher the pH (or more alkaline the skin) the more severe the nappy rash. The presence of urine and faeces in this area generates ammonia, which in turn produces an alkaline environment. This alkaline pH activates faecal enzymes which break down the skin barrier. An elevated pH also lowers the skin’s resistance to the fungus C. albicans, which is the microorganism most associated with diaper dermatitis.
Cutibacterium acnes, the bacterium mostly associated with acne, grows well at pH values between 6 and 6.5, while there is less growth at pH values under 6. In a study of acne-prone patients, the number of acne lesions in subjects using a conventional alkaline soap when compared with those using an acidic synthetic detergent (syndet) bar, proved that the number of inflammatory lesions increased in the alkaline soap group and decreased in the group using the acidic syndet at statistically significant levels by the fourth week of application.
Skin pH and antimicrobial properties
The biome, also known as the microbiome, of the skin consists of a multitude of living organisms and is proven to be of huge importance in the skin’s health, as well as the general well-being of the individual. Several studies have shown a direct relationship between a healthy microbiome and the health of someone’s immune system. Normal biome growth is optimal at acidic pH levels, whereas disease-forming bacteria, such as S. aureus, thrive at a neutral pH level. Even a slight increase in pH on the skin’s surface from 6.0 to 6.5 causes a dramatic rise in S. aureus levels.
Research findings show clearly that the use of acidic cleansers and serums would potentially benefit the skin, and aid in the management of cutaneous diseases such as acne, AD, fungal infections, and irritant contact dermatitis. This benefit is two-fold, namely:
- Changing the skin’s pH to a more acidic level will hugely benefit the function and appearance of the skin.
- Acidic ingredients like hypochlorous acid, hyaluronic acid, ascorbic acid (Vit. C) and retinoic acid, which all have beneficial effects of their own on the skin, are ideally suited for inclusion in products formulated at an acidic pH.
Our recommendation is that you use a body wash or cleanser that has a pH between 4.5 and 5.5, which is closer to the healthy pH of the skin. Synthetic detergent bars or clear liquid cleansers perform better than soap. A bar of traditional soap is very alkaline and has a pH of 9 to 10. This alkalinity can cause skin irritation, disturb the barrier function, and inhibit biome growth and function. Often, patients with acne, believing that their problem is related to poor hygiene, overuse harsh soaps exacerbating the condition, and a vicious cycle of further cleansing ensues. Avoid cream-based cleansers and makeup removers. Ideally use an inexpensive pH strip to check if your current cleanser or soap is too alkaline and, if so, look for a more acidic alternative, your skin will thank you.
More about hypochlorous acid
Here are some key benefits to using cosmetic-grade hypochlorous acid (HOCl) as found in our GF2 formulations, as your principle skincare product.
- GF2 has a pH of 5.6, this is at the ideal acidity level for maintaining the skin’s acid mantle.
- GF2 contains no preservatives nor any other ingredient except water. This ensures that no harm to the biome, or the environment, is caused.
- GF2 is multifunctional. It reverses ageing, controls inflammation, and heals inflammatory diseases like acne and Rosacea.
- GF2 helps to recover the skin’s barrier function and the function of the oil glands and melanocytes (pigment-forming cells in the skin). This restores an even healthy tone in the skin. As the barrier function recovers (with regular use) skin hydration also returns to normal, which may reduce the skin’s dependency on moisturisers.
- GF2 protects against sun damage.
More has been discovered in the last decade about the role of the skin’s pH as a factor in vital skin barrier function. We still have much to learn about the complex relation of skin pH and downstream pH dependant diseases. What we do know is that skin with an alkaline or raised pH is often characterised by a faulty barrier function and will suffer with skin diseases as mentioned. This should prompt the science-conscious consumer to focus on preserving or restoring an acidic environment on their skin by selecting skincare products that are compatible with, or support, the natural acid mantle.
- Ali SM, Yosipovitch G. Skin pH: from basic science to basic skin care. Acta Derm Venereol. 2013 May;93(3):261-7. doi: 10.2340/00015555-1531. PMID: 23322028