Starting with this article, I plan to use a series to teach you about the relationship between various vitamins and skin health, and how to use these vitamins correctly.
As the first article, let's first take stock of the most popular A alcohol-Retinol.
Retinol is a form of vitamin A, The reason why it is called Retinol, It is because it is closely related to vision: rod/cone cells (a kind of cells in retina) generate electrical signals after receiving illumination, and the electrical signals are converted into visual signals after being detected by nerves. This process depends on a very important substance-rhodopsin, and the photosensitivity of rhodopsin mainly depends on Retinol.
Retinol plays a very important role in general health, especially in skin health: when the human body lacks vitamin A, it may cause hyperkeratosis of skin. At the same time, vitamin A also has a very extensive and profound regulatory effect on various cells and organs of the whole body. For epidermal cells, its most important effect is to inhibit over-differentiation of epidermal cells. A new concept is introduced here, "What is the differentiation of epidermal cells"? We call the outermost layer of skin stratum corneum, below which is granular layer, then spinous layer and basal layer.
The cells in the basal layer are mainly epidermal stem cells, After they split, they gradually move up from the basal layer, In this process, the morphology also changes constantly, from the original square or column shape to a relatively flat shape, the cytoplasm is also continuously concentrated, and a large number of dark particles appear, and finally become as thin as scales (i.e., keratinocytes), which are closely stacked together to form the stratum corneum. This process is called differentiation. What does over-differentiation mean? If the cutin is too thick, the connection of keratinocytes may become loose and rough. Because they are not closely connected with each other, and the cuticle is too thick, which leads to the decline of skin's reflection ability to light, so the overall gloss of skin will also decline.
Sebum-secreting cells are sebaceous gland cells, and the process of sebum secretion also belongs to differentiation process. This kind of cell will continue to synthesize a large amount of oil until it fills the whole cytoplasm, causing the cell to break down and finally releasing oil. Vitamin A can inhibit sebum secretion because it can inhibit cell differentiation (of course, there are other mechanisms for inhibiting sebum synthesis), so most oil control and acne removal products contain Retinol or Retinol derivatives.
Retinol also has a regulatory effect on dermis, and its main function is to promote the proliferation of dermal fibroblasts and the synthesis of collagen, which is the reason why vitamin A has obtained the most clinical evidence among many anti-aging, anti-wrinkle and dermal elasticity products on the market. In the 1960s, Professor Kligman discovered trans-tretinoin (a form of vitamin A), It is obtained from the continuous oxidation of Retinol. Since then, researchers have been studying its anti-aging mechanism, and obtained a lot of basic and clinical research evidence. Many clinical experimental data have confirmed that applying retinoic acid to light-exposed parts can significantly reverse photoaging and play a good anti-aging role.
Here, let's make a summary of the three main functions and principles of Retinol in beauty:
First of all, vitamin A can regulate the differentiation process of skin keratinocytes (mainly inhibit excessive differentiation), thus making skin smoother. Second, vitamin A can inhibit sebaceous gland cells to synthesize sebum, and play a role in controlling oil and eliminating acne. Third, it can reverse photoaging, making dermis more elastic and wrinkles shallower.
Vitamin A-Benefits and Risks Coexist
Because vitamin A is a highly effective ingredient, And the regulation is very comprehensive, Therefore, there will be various reactions during its use. Especially, when most people use Retinol, they are prone to peeling and obvious stimulation, and even individual users may have skin color changes: some people are prone to redness (because they are sensitive to stimulation), while others are prone to blackening (because the light response system involved in melanocytes also depends on Retinol). Studies have found that, Vitamin A can enhance the photosensitivity of melanocytes, This is the root of the so-called "early C and late A", which leads many people to think that vitamin A can't be used during the day. In fact, the core of this problem lies in: when the photosensitivity of our skin increases, if we don't pay attention to sun protection, the consequences will be more serious. Therefore, it is not that vitamin A can't be used during the day, but that it can be used normally as long as we do a good job of sun protection.
In the process of using Retinol, some people may not tolerate it. My advice to you is:
Then, I hope to give you a friendly reminder: there is no panacea in skin care, which can achieve decathlon, and every aspect is perfect. Now the role of vitamin A is deified to some extent: Although it does work in some ways, But there are shortcomings, For example, Europeans and Americans may use tretinoin in the treatment of chloasma. However, this method is not very suitable for Chinese people, because our pigment cells are more sensitive, and the skin of non-East Asian people is quite different from ours, which has been proved by studies. They may be able to tolerate high concentrations, but we Chinese may not be able to tolerate them. If you can't tolerate it, don't be superstitious about piling up the concentration of raw materials higher and higher. My own opinion is to exquisitely balance all the ingredients in the formula, let them work together, foster strengths and avoid weaknesses, so that the formula can really play a three-dimensional role in skin care from various targets. Nowadays, many people like the practice of "raw material barrel": the original concentration of 0.1% is enough to make the product have good effects, and the intensity of adverse reactions is just controlled within the tolerable range, but some people just want to pursue higher concentration. For example, a person's stomach can only accommodate one steamed bread, but he has to eat ten steamed buns. How can this be done? It is necessary to do what you can for the stomach, and it is also true for the skin.
How to supplement vitamin A?
Vitamin A supplementation can only be done orally and externally:
Retinol or its derivatives can be used for external use. At present, derivatives that can be used in cosmetics include Hydroxypinacolone Retinoate, Retinyl Retinoate, Retinal, retinyl palmitate, Retinol acetate, RETINYL PROPIONATE and so on. These ingredients all work through similar ways, which may have different efficiencies and different mildness. It is impossible to judge which ingredients you can tolerate. It is also necessary for everyone to pay attention to the feelings and changes of their skin when using them.
Oral vitamin A supplementation is mainly through intake of beta carotene. Beta carotene is combined by two Retinol molecules. After it is linked by corresponding enzymes in human body, it will become two Retinol molecules, thus playing the role of Retinol. It can also be stored and used when the human body needs it. Beta carotene generally exists in orange-red foods, and is abundant in citrus, pumpkin, carrot, papaya and tomato, so you can choose bright foods with orange or dark green colors.
- Before using vitamin A, we should be fully prepared for the adverse reactions it may cause;
- For mild reactions, if you can tolerate them, you just feel tight, dry or slightly desquamated, you should pay attention to moisturizing and avoid excessive skin friction;
- If you really can't stand it, you should reduce the concentration, reduce the frequency of use or stop using it.