No matter how times change and beauty technology advances, the structure of the skin never changes. That's why it's important to always go back to the basics when it comes to skin care. To keep skin fresh and beautiful, it is best to understand the structure of the skin and improve its ability to retain moisture rather than introduce various beauty ingredients from the outside. The foundation of skin care is hydration. If the skin mechanism is not damaged and the skin is well hydrated, skin problems are unlikely to occur. This is because hydration is the barrier function of the skin itself.
The skin's moisturizing factors are concentrated in the stratum corneum of the epidermis. There are three types of moisturizing factors: sebaceous membrane, intercellular lipids, and natural moisturizing factor (NMF). When these moisturizing factors are in good balance, the skin remains healthy. The thickness of the stratum corneum is only about 0.02 millimeters, the same thickness as a sheet of plastic wrapping. In this ultra-thin stratum corneum, an extremely elaborate moisture retention mechanism is installed. First, there is a film of sebum on the upper surface. Under that, there are 10 to 20 alternating layers of water and oil, and inside the horny cells there are natural moisturizing factors (NMF) and keratin, which give the skin its flexibility and elasticity. This elaborate mechanism serves as a barrier between the outside and inside of the skin. If it were to be disrupted by any force, we could expect skin problems. Let's get into the details of this stratum corneum to better understand the three factors of skin hydration.
Three hydration factors of the stratum corneum
Ceramide and natural moisturizing factor (NMF) are produced when epidermal cells are pushed upward by turnover to become horny cells. 40% of the intercellular lipids in the stratum corneum, which fill the spaces between the 10 to 20 layers of horny cells, are made up of a substance called ceramide. The ceramide, in combination with the natural moisturizing factor (NMF) of the corneocytes, has a strong moisture-retaining capacity. The sebaceous membrane, intercellular lipids, and natural moisturizing factor (NMF) are the three components that retain moisture.
The amount of moisture stored in the skin is estimated at 30–40% for healthy skin. If the quantity of ceramides in the intercellular lipids is normal, the skin does not dry out, even in dry desert areas. However, when the barrier function is broken and dry skin occurs, the water content drops to about 10%, which is a difficult situation. The contribution of each hydration factor to water retention is 2% for the sebaceous membrane, 80% for intercellular lipids, and 18% for NMF. The level of ceramide in intercellular lipids is reported to be 40%, indicating that ceramide plays a major role in moisture retention.
Now that we are aware of the composition and role of the different hydration factors in the stratum corneum, how can we protect and maintain these essential elements for the health and regeneration of the skin ?
Maintaining the skin's barrier function is the key to moisture retention
The first layer of the barrier function, which acts as a barrier on the skin's surface, is the sebum film. The sebum film is formed by the fusion of sebum secreted by the sebaceous glands and sweat. Epidermal commensal bacteria, such as Staphylococcus epidermidis, play a major role in the production of this membrane. Although epidermal commensal bacteria are good bacteria, they are easily eliminated by washing or cleansing the face. Therefore, the temperature of the water used for face washing and bathing should not be too high. If the bathing time is too long, the sebum film will be removed. It takes one to two hours for the lost sebum to regenerate, so a lotion is applied to protect the skin instead of the sebum film during this time.
The sebum film produced by the commensal bacteria of the epidermis is considered nature's best cream. It prevents moisture from evaporating and keeps the skin's surface slightly acidic, thus preventing allergens and bacteria from invading the skin. Since bad bacteria, such as Staphylococcus aureus, prefer alkalinity, keeping the skin slightly acidic inhibits their growth. Excess sebum can oxidize and cause inflammation and acne, so remove it lightly by washing your face morning and night.
When the level of moisturizing factors decreases due to a decrease in metabolism, the level of sebum decreases as well, causing the skin to become crusty, powdery, and itchy. Add to this aging, excessive cleansing, and dry air, and the skin becomes progressively more susceptible to dryness. Stress, lifestyle disorders, lack of sleep, excessive alcohol consumption, etc. can also lead to a decrease in moisture levels. When skin regeneration is disrupted, ceramide is not sufficiently produced, which leads to a decrease in moisture levels and barrier function. A good night's sleep is also an important factor in normalizing skin regeneration.
Most women already know the impact of these things on their skin. However, all of them can damage their skin with a simple daily task that they never pay attention to.
Be careful not to over-wash your face.
To maintain moisture, don't over-wash or cleanse your face, and moisturize it as soon as possible after washing, as moisture tends to evaporate easily. Also, be sure to protect yourself from ultraviolet rays when you go out. When sebum secretion decreases, moisturizing is the only way to compensate. The ideal is to moisturize with ingredients that are as close to human sebum as possible. It is important to note that if petroleum-based chemical cosmetics are used for a long period of time, even up to 10 years, the barrier function deteriorates or becomes destroyed, resulting in decreased water retention and a tendency to develop dry skin.
There is no doubt that the human body and the skin are made up of dietary nutrients. Therefore, it is important to take in foods that contribute to the retention of moisture within the body. We should consume unheated foods such as vegetables, fruits, and pickles, as well as high quality proteins, dietary fiber, and vitamins such as beans. Dietary fiber helps remove toxins from the body. Birch sap is also a very useful drink because of its ability to remove and detoxify active oxygen in the body, hydrate from within, prevent blemishes and dullness, regulate cell regeneration, and reduce daily stress and fatigue.