The outermost layer of the skin is the epidermis. This layer is, in turn, formed by several sublayers containing mainly keratinocytes that are positioned in ascending layers according to their maturation degree. The last state of maturation of the keratinocytes occurs when these cells have a high content of keratin and a compact morphology. At that time, they are known as corneocytes and placed in the shallower layer of the epidermis, known as the stratum corneum. In the stratum corneum, cells are attached to each other thanks to the presence of intracellular lipids and the entire structure is covered by a thin layer of fat and sweat that gives the skin a slightly acidic pH (around 5.5). This structure functions as a perfect protective shield of the skin: the corneocytes are robust and waterproof cells; lipids act as the glue between them fixing moisture and preventing water loss, and the hydrolipid film avoids water loss and prevents infections. This insulating function is vital for humans to be able to live on Earth and is known as the epidermis barrier function.
However, despite the apparent robustness of this layer, the stratum corneum is not a static barrier. The dead corneocytes accumulate in the most external layer until they detach from our skin and are replaced by other corneocytes in a process known as desquamation or peeling. The half-life of a Keratinocyte is approximately 28 days so this cell renewal process occurs quite frequently.
Although the peeling process occurs naturally, exfoliating the skin helps to make this process faster. The exfoliation process involves exerting an abrasive force on the skin, which can be physical or chemical, so that the cells on the surface break off. In most cases, this abrasive force is physical and is exerted through the use of sponges, brushes, or soaps with small particles that, when repeatedly rubbed on the skin, release dead cells. In contrast, chemical scrubs are those products that achieve the removal of the most superficial cells for their chemical properties. These molecules are commonly acidic, such as glycolic acid, which drastically decreases the pH of the skin by exerting an abrasive action. As a result, the skin remains “naked” from its protective barrier and has to generate new cells that replenish it. This is why regular exfoliation is said to help regenerate epidermis cells.
However, we need to be careful since an inadequate exfoliation method or frequency can be harmful to our skin. To make sure we don’t damage our skin we need to keep a few things in mind:
1. What exfoliating method should I use?
Exfoliating our skin involves subjecting our skin to an abrasive process and this is not recommended for all skin types. If you have very thin, sensitive skin or have a dermatological condition such as rosacea or atopy, it is better to check with your dermatologist before starting to have frequent exfoliations, as they can worsen the appearance of your skin.
In contrast, if you have oily skin, it is better to start step by step. Begin using a brush or soap with small particles and, if your skin responds well, you can switch to chemical scrubs, always starting with low concentrations and gradually increasing. Although slight irritation after exfoliation is normal, if it persists for several days, visit your dermatologist.
2. How often should I exfoliate my skin?
A very frequent exfoliation can damage the deeper layers of our skin as we would not be leaving enough time for the stratum corneum to regenerate completely and, therefore, the inner layers of the epidermis would be exposed to the action of the exfoliator and the external environment. In addition, by removing the stratum corneum, the skin is more vulnerable to infections and dehydration. Repeating this process very often would result in too much water losing and dryness, causing discomfort and tightness.
Exfoliating your skin once a week is usually enough to maintain cell renewal without causing dehydration. However, there are soaps with small exfoliating molecules that can be used more often as their abrasive power is low.
We must also take into account the area of the skin that we want to exfoliate. We should avoid exfoliating very often the areas most prone to dryness. In contrast, areas where the skin is thicker, such as the soles of the feet, can be exfoliated more often. Finally, the skin on the face is extremely sensitive and we should not establish a facial exfoliation routine based on the results we have obtained in other parts of the body. As mentioned above, on the face it is advisable to start gradually with low aggressive exfoliation methods and increase the frequency or intensity of the exfoliation based on the needs of our skin.