Everything you need to know about skin pH

When we talk about pH, the first things that come to mind are often vague memories of high school chemistry classes. But did you know that in the human body, pH plays a crucial role in the proper functioning of cells and organs? And that skin pH is an important factor to consider when trying to maintain healthy and balanced skin?

In this article, we invite you to discover everything you need to know about skin pH. We explain its role, what can cause it to change, and howFilorga cosmetic treatments help maintain it for radiant skin.

What is pH?

Invented by Danish chemist Soren Sorensen in 1893, the concept of pH (or hydrogen potential) is an indicator of the acidity or alkalinity of a solution or liquid. pH has no units, only a number between 0 and 14. data-mce-fragment="1">A value less than 7 indicates an acidic solution. A value greater than 7 indicates a basic or alkaline solution. data-mce-fragment="1">.

Here are some common pH examples:

• Stomach acid: 1-1.5
• Orange juice: 3.5-4
• Black coffee: 5
• Milk: 6.5-6.8
• Sea water: 7.5-8.4
• Bleach: 12.5
• Laundry detergent: 13-13.6

Note that an acidic food like orange juice will never be harsh on the digestive tract. In fact, it will pass through the stomach anyway, which contains gastric juice, one of the most acidic liquids there is. Acid doesn't pose any problems as long as... it stays in the stomach.

In nature, living organisms need a certain pH to live and grow. Thus, some plants are better suited to acidic soils (pH between 4 and 6.5), while others need basic or calcareous soils (pH 7 to 8).

The same is true for humans, for whom pH is of major importance.

pH in the human body

The pH of human organs is tightly regulated and ranges from 1 to 8. Outside of this range, various enzymes cannot be activated, which can block certain reactions essential to our metabolism. The body must therefore constantly maintain the pH of the organs within their optimal operating range. data-mce-fragment="1">For example, the respiratory and renal systems constantly regulate blood pH to maintain a pH between 7.35 and 7.45, as any variation (especially toward acidosis) can be potentially fatal.

Another example mentioned above: the stomach has a very acidic pH of 1 to 1.5 when fasting. This is important for predigestion and defense against bacteria. A lack of acidity can cause gastrointestinal infections, while excess acidity (below pH 1) can cause gastric ulcers.

The pH of certain organs can also vary slightly throughout the day. This is the case for tears, which are more acidic in the morning when they come from an unopened eye than later in the day (average pH of 7.25 versus 7.45).

Why is skin pH important?

The skin is covered with a hydrolipidic film on the surface of the epidermis. This film, also called the acid mantle, has a slightly acidic pH of between 4.5 and 5. This acidic pH promotes the growth of "good" bacteria in the skin. data-mce-fragment="1">skin microbiota and formsa protective barrier against pathogenic bacteria present in the external environment. It also contributes to the integrity of the stratum corneum (Stratum corneum) by regulating the enzymes involved in its desquamation, i.e., the removal of dead cells from this superficial layer of the epidermis. When the skin's acid mantle is unbalanced, problems can arise, such as:

• Irritations;
• From the drought;
• Infections;
• Acne.

Maintaining a balanced skin pH is therefore essential to allow the skin to preserve its barrier function and defend itself against external aggressions, while maintaining the hydration and suppleness necessary for healthy skin.

What can affect skin pH?

The skin's natural pH can be influenced by several endogenous (specific to human physiology) and exogenous (external) factors. The most important ones are:

Age

Studies have reported relatively neutral surface pH values ​​(around 7) in newborns, with a decrease to around 5.5 during the first 4 days of life. This pH gradually stabilizes between 4.5 and 5 as we move into adulthood, with localized variations during adolescence (particularly with the appearance of acne pimples on the face).

In people aged 18 to 60,skin pH varies little and generally remains constant at most anatomical sites.

On the other hand, it tends to increase in older people.

Gender and Ethnicity

People with black skin have a lower skin surface pH than people with white skin. A recent study also revealed a higher pH in women (5.6) than in men (4.3).

Cosmetic Products

Among the many external factors that influence skin pH,one of the most important iscleansing. Typically, the following are observed:

• A significant increase in pH for at least a few hours after cleansing the skin with alkaline soaps (pH 10.5-11.0).
• A lower and shorter-lasting increase after using tap water or cleansers formulated with the same pH as the skin.
• A very limited increase with the use of formulas containing surfactants (also called surfactants or surfactants).

In all cases,this increase is reversible and pH values ​​return to normal after a few minutes or hours.

Does pH influence skin type?

Oily skin will tend to have a less acidic pH than normal, which promotes the proliferation of bacteria involved in acne. On the other hand, dry skin will have a lower pH, which can cause irritation and itching. Combination skin, on the other hand, is characterized by areas that have a different pH.

It is therefore essential to balance the skin's pH to maintain healthy and radiant skin. This is why the experts at FILORGA Laboratories recommend using skincare products that are adapted to each skin type.

Filorga cosmetics respect the skin's pH

All our skincare products aresubject torigorous dermatological tests to ensure their tolerance and that they do not cause adverse reactions under normal conditions of use. They are suitable for sensitive skin, and their skin-neutral pH corresponds to the natural level of the epidermis.

The pH of the creams is also adapted to the active ingredients toensure optimal effects. For example:

• AHAs (alpha-hydroxy acids) used as exfoliants or moisturizers need to be added and maintained at a very acidic pH.
• Pure vitamin C is rapidly oxidized (or degraded) by the oxygen in the air. It is a very unstable natural acid, whose scientific name is ascorbic acid, which must also be formulated at an acidic pH, around 3.5. However, its derivatives can have higher pH values ​​because they are stabilized. This is the case for ascorbyl glucoside, which is found in the skincare product HYDRA-AOX [5] , the glucoside function of which helps to "protect" vitamin C from oxidation.
• Gluconolactone must be added at a pH below 6 to be able to be converted into gluconic acid, which is the active form of this exfoliant.

Ph can also play an important role in the product's sensory quality: some gelling agents are dependent on the overall pH of the product in which they are included. An incorrect pH (or changes in pH over time) can alter the product's viscosity and therefore its sensory quality.

In conclusion, pH is an essential component of the skin's barrier function. This is why it is essential to use beauty products that respect this pH. It's also important to keep in mind that skin is naturally acidic, and a product with a neutral pH for the skin does not necessarily mean neutral. As we saw above, this corresponds to a pH between 4.5 and 5.

Sources:

Proksch E. pH in nature, humans and skin. J Dermatol. 2018 Sep;45(9):1044-1052. doi: 10.1111/1346-8138.14489. Epub 2018 Jun 4. PMID: 29863755.