Are the facial masks we use every day useful? Are they just a waste of money?

Facial masks, as one of our daily skin care products, must be familiar to everyone. Some people say that facial masks have a strong moisturizing effect. Is there any basis for this? Or is it just a marketing trick, which is what we call IQ tax? Then why do so many people use them? Today, let's talk about this matter of facial masks.

01.Structure of the skin

To talk about the role of facial masks, we have to start with the skin. Let's take a look at a simple skin model.

Generally speaking, our skin is composed of three parts: epidermis, dermis and subcutaneous tissue. The epidermis is roughly divided into the following contents.

The stratum corneum is what everyone is most familiar with, and it is also where most skin care products work (including facial masks, of course) . The stratum corneum is a layer of dead cells! (This sentence is very important)

Since they are dead cells, they will become dry and flaky when lacking water, and become smooth and elastic when absorbing water. This is essentially the effect of water, and most masks, including various hydrating measures used in daily life, focus on this function. Of course, in order to enhance the function, there will also be various "locking water/moisturizing" functions, which actually add a layer of isolation material to reduce the evaporation of water to a certain extent, such as the most classic glycerin ingredient.

The current facial masks basically have this function.

02. What are the sources of nutrition for the skin?

In fact, since the skin is composed of cells, the nutrition source of the skin must be composed of two parts:

1. Nutritional supply for the human body, which is the main source of nutrition, supplies nutrients to cells through body fluid systems such as capillaries and interstitial fluid

2. External nutrients, mainly various exogenous substances, typically skin medications . The application of various ointments for treatment shows that the skin can penetrate these drugs.

Therefore, there is no reason to rule out the effects of exogenous substances on the skin . The real structure of the skin is cells, and cells are not intelligent systems. Cells do not particularly distinguish the source of substances when absorbing them. They mainly judge the structure and type of the substances. For example, when giving cells growth factors, whether they are synthesized by the human body or extracted from other human bodies, as long as the structure is the same, the cells will recognize them.

03. One of the functions of facial mask

From the above, we can see that the function of facial masks is definitely to retain moisture, but it is definitely more than that. (A simple logical counterexample is: some people are allergic to facial masks. If it is just to replenish moisture, how can they be allergic? This means that other ingredients must have reached below the stratum corneum.) Therefore, the function of facial masks includes at least two parts:

1. Moisturizing - the main function, about 99% or more

2. Nourishing - very few facial masks have this effect.

But, does the mask really have no other function???

Strictly speaking, I am against this statement.

Because, since chemical substances are added to the skin, it is understood that some substances will penetrate through the stratum corneum into the deeper living cells of the skin. At this time, what role do these substances play?

If you have studied cell biology or have done relevant cell experiments, you will know that cell culture requires quite a lot of substances. Let me give you an example - basic culture medium components:

Glucose – Energy

Amino Acids - Nutrition

Inorganic Salts - Osmotic Pressure and Ions

Vitamins – Nutrition

For example, the familiar DMEM high-glucose culture medium (used for growing cells). In addition, if some cytokines can be added, the cells will grow better, such as growth factors (there are many types of growth factors, mainly polypeptides) and antioxidants ( antioxidants exist in a dynamic balance, too high or too low is not good )

These substances have been shown to promote cell growth and therefore may also promote skin health to a certain extent.

04. The second function of facial mask

The second function of the mask is to provide nutrition (similar to cell culture medium). However, it should be pointed out that there are not many masks that can provide nutrition, because this involves at least the following factors:

1. The carrying capacity of the mask itself. Most masks cannot carry too much material.

2. The effect of additional nutrition on the skin: too little will not reach the living cells, and too much may irritate the skin and cause side effects (after all, simply applying a mask is still not as good as the cells themselves synthesizing nutrition and the body's precise control of nutrition)

3. The shelf life of nutrients is also an important factor. Many of those active substances are time-limited. If they are not properly preserved, many problems will arise, such as becoming a large bacterial culture medium or changing the material structure, thus losing their effectiveness.

Therefore, I think the cost of a mask that can achieve this effect should be quite high .

As for some functions, I give the following credibility

1. Moisturizing, Credibility ★★★★★

2. Antioxidant, Credibility ★★★

3. Whitening, credibility★★

4. Anti-aging, credibility★

The above credibility evaluation is mainly based on personal knowledge of some materials in current cell culture and research and judgment on the development of its commercial production.

05. Effects of cytokines on cells

The above are some popular sayings. Here I will give some examples of the effects of cytokines on cells. EGF, Epidermal Growth Factor, this substance mainly promotes the growth and division of epidermal cells, epithelial cells, and fibroblasts, promotes the growth of microvessels, and improves the microenvironment for cell growth. EGF is very famous and won the Nobel Prize in 1986.

Signaling pathways

For example, EGF can promote the healing of skin damage.

Hardwicke J, Moseley R, Stephens P, et al. Bioresponsive dextrinrhEGF conjugates: in vitro evaluation in models relevant to its proposed use as a treatment for chronic wounds［J］. Mol Pharm, 2010, 7(3): 699-707.

There are also a range of skin medication ingredients that may be added, and these countries have regulations...