1, the method of eliminating melanin
Whitening only minimizes pigmentation.
"It is easy to get tanned by the sun in summer, which is a way for the human body to protect itself. Ultraviolet rays stimulate melanocytes to synthesize a large number of melanin particles, which makes the most important DNA part in our cells less damaged. " Professor Yanwu, deputy chief physician of the Department of Dermatology and Sexology, Peking University First Hospital, said. All whitening measures, whether medical means or life beauty, can not change people's original basic skin color. The melanin inherent in the original basic skin color is genetically doomed, and all the acquired "whitening" measures are to avoid and minimize excessive pigmentation induced by external factors such as ultraviolet rays and drugs. In fact, the concept of "whitening from the inside out" declared by advertisements may mislead consumers-the efforts of the day after tomorrow can only restore the skin to its original basic color, and blacks cannot whiten through "whitening".
The content of melanin is the decisive factor of blackening.
So how do people turn black?
Everything is related to melanin. The epidermis of human skin is divided into five layers, and the bottom layer is the basal layer, which contains a large number of melanocytes that can produce melanin.
When the skin is irradiated by ultraviolet rays, it will induce a lot of free radicals, inflammatory factors, collagen damage and even DNA movement. At this time, in order to protect themselves, the skin will produce a lot of melanin to absorb ultraviolet rays. When exposed to ultraviolet rays, melanin is oxidized by oxygen free radicals produced by UVA into darker oxidized melanin, which redistributes and transfers to the stratum corneum, even forming spots and pigmentation, and the skin color will darken immediately. Lalunasun, a contributor to Shell Network, said that in the next long time, more melanin will be produced, which means that the skin will be darker than before in a few months after sun exposure.
Melanosome in melanocytes contains tyrosinase and structural proteins. The former is the key to melanin synthesis, and the latter is the component of melanin. Lalunansun said. Tyrosine is converted into dopa by tyrosinase, which is the first decisive step in melanin synthesis. The amount of melanin synthesis is positively correlated with tyrosinase activity. Tyrosine is an essential amino acid for physiological activities and widely exists in human body. The tyrosinase activity in dark skin is about three times that in light skin.
"Skin care products can affect the survival of melanin by using some ingredients, such as hydroquinone, arbutin and ellagic acid; Vitamin C, kojic acid, tranexamic acid and azelaic acid can affect melanin production and block melanin transmission; Promote melanin metabolism, such as salicylic acid and fruit acid, "said Xin Li, a cosmetic researcher.
Whitening should also pay attention to safety
"Hydroquinone, which affects the survival of melanocytes, has been proved to be effective for chloasma caused by sun exposure or hormones, and has antioxidant function at the same time. However, hydroquinone is not only irritating to the skin, but also carcinogenic, so it is banned by the European Union. In the United States, it is not allowed to use more than 2%, and a prescription is required. However, it is not prohibited in China. " For example, the founder and head of SummerStudio, "Beauty King and Chemist", said, "Derivatives such as vitamin A aldehyde/ester/alcohol, which can block melanin transmission and accelerate metabolism, must be protected from light when used."
"kojic acid is a yeast extract in the so-called Japanese sake brewing process. Some studies say that it can prevent the formation of melanin, but kojic acid itself is unstable and easy to be oxidized or decomposed by sunlight. Cosmetics use relatively stable derivatives, whitening is not so effective, but the antioxidant effect is good. In addition, kojic acid can irritate the skin and cause allergies. "
"Whitening ingredients used after melanin formation, such as α-hydroxy acids, are often called AHA. They usually exist in cosmetics in the form of lactic acid and glycolic acid because of their small molecular weight and easy absorption by skin. Generally, AHA with a concentration of 4% to 15% can not effectively whiten the skin, but can only exfoliate. 50% or higher concentration of AHA may have whitening effect. "
Because melanin needs the participation of free radicals in the production process, it can also enhance the whitening effect to some extent when used together with antioxidant products and whitening products.
Q: Will the use of whitening products make the skin thinner and more sensitive?
Xin Li (Cosmetics Researcher): If you use fruit acid and salicylic acid which promote melanin metabolism, it may cause skin thinning.
Yanwu (Deputy Chief Physician, Department of Dermatology and Sexology, Peking University First Hospital): Whitening skin care products are not only composed of a single ingredient, but also contain many ingredients with different whitening mechanisms, which can prevent, block and alleviate different links of melanin formation. Only using fruit acid to accelerate melanin metabolism will have a certain impact on the thickness of the stratum corneum, and other ingredients will not affect the stratum corneum. When the skin is well tolerated and not easily sensitive, the concentration of fruit acid of about 5% and salicylic acid of 0.5%- 1% can be used to accelerate the metabolism of melanin.
Q: What whitening methods are different from life beauty in medicine?
Yanwu: Vitamin C, vitamin E, B vitamins and bean products that can inhibit melanin are used in medicine. To whiten the skin, and with the synergistic effect of antioxidants, the whitening effect is better. For example, vitamin C is introduced into this medical method for beauty.
Xin Li: Photon rejuvenation can be used to whiten skin in medicine.
Q Is it safe to inject whitening needle containing VC, glutathione and potassium ammonia into vein?
Yanwu: At present, China has not approved the use of whitening needles.
Xin Li: The whitening needle is not safe. First, many ingredients of whitening needles are made by beauty salons themselves; Second, because the main components of whitening injection may cause vascular irritation or thrombosis, which is life-threatening.
Q will primary skin turn black because of aging? Is that the older people get, the easier it is to turn black?
Yanwu: In fact, with the increase of age, people's skin color will gradually turn white, because the survival rate of melanocytes caused by aging is getting lower and lower. However, the main problem caused by aging is uneven skin color. Some melanocytes in the skin have reduced the function of producing melanin, and some melanocytes are very active, which is easy to produce senile plaques and will cause the illusion of skin blackening.
Q Can whitening skin care products be used to remove freckles?
Yanwu: Whitening products and freckle removing products have different ingredients, so whitening products can't freckle.
Q ultraviolet rays are divided into UVA and UVB. It is said that the ultraviolet damage caused by UVA can't be repaired by any after-sun repair product? That is to say, it is still possible to come back for nothing after tanning, but there is no room for recovery when you are old.
Yanwu: This statement has no scientific basis. Ultraviolet damage caused by UVA or UVB is cumulative and can be recovered naturally. In fact, UVA, which accounts for 95% of ultraviolet rays, can penetrate deep into the dermis of our skin, and UVA protection products generally contain antioxidants.
However, it is precisely because of the harm of UVA that people should use broad-spectrum sunscreen all year round to protect both UVB and UVA. It should be applied evenly and in a certain amount. The amount of the whole face needs to be close to 1 g to achieve a good sunscreen effect, and it is also important to apply it again.
Can foods such as coix seed and rice soup play a whitening role?
Yu Renwen (nutritionist, Air Force General Hospital): Foods such as coix seed can't play a whitening role.
Yanwu: Usually, you can take in more antioxidants. For example, fresh vegetables and fruits are rich in vitamin C, and foods such as green tea and soybeans can also resist oxidative damage caused by ultraviolet rays and protect the skin, but they cannot whiten.
It's better to do it late after sun exposure than never.
Professor Yanwu, Deputy Chief Physician, Department of Dermatology and Sexology, Peking University First Hospital.
1, cold compress immediately after sun exposure or repair with soothing and anti-inflammatory skin care products after sun exposure. If you use skin care products containing chamomile, licorice and other natural plants at the same time, the effect will be better.
2, it is necessary to pay attention to moisturizing after sun exposure, ultraviolet radiation will inhibit the skin's own moisturizing factor synthesis, the skin will become dry, and the stratum corneum will thicken.
3. Skin care products containing fruit acid and vitamin C can accelerate the recovery of skin color. Cosmetics containing fruit acid can accelerate the synthesis of melanin and excrete it through the renewal of skin stratum corneum. Vitamin C has a strong antioxidant effect, which can transform the synthesized melanin particles into a reduced state and dilute the color. Now there are some new ingredients, such as lignin peroxidase, a biological enzyme isolated from fungi, which can decompose melanin that has been synthesized in cells.
2, skin oil control coup
The first step of degreasing: oil sweeping.
If you want to get rid of oily face in a short time, it can't be achieved completely by supplementing vitamin B2. What we have to do at this time is to remove oil, that is, to clean the skin.
Choose a mild cleanser with oil control effect, and clean the forehead, nose, chin and cheeks from bottom to top and from inside to outside. Most people have too much oil in the T-zone, nose and chin, so be sure to pay attention to these parts when sweeping oil.
Degreasing Step 2: Clean up the grease.
If you want to remove the oil skin, there is another thing you can't forget, and that is to clean up the oil. Choose a gentle exfoliating scrub and clean the grease 1-3 times a week, which can not only * * the skin, but also reduce the acne caused by excess oil. At the same time, it can also remove all kinds of dirt in pores.
The third step of degreasing: inhibit oil secretion.
Of course, we must find ways to inhibit oil secretion after cleaning up the oil shine. At this time, you can choose some toner with firming effect, and the toner containing alcohol is more suitable, because when alcohol volatilizes on the skin surface, it can take away skin heat, shrink pores, inhibit skin from secreting oil, and adjust skin acid-base balance. This method of inhibiting oil secretion is very effective, but it is a pity for sensitive skin. Alcohol toner should be used with caution.
The fourth step of degreasing: balance oil secretion.
Balance oil secretion, but it can't escape moisturizing and hydrating. It is best to choose some refreshing and moisturizing lotion or cream containing fruit acid. Fruit acid can not only inhibit the formation of acne, reduce wrinkles, but also balance the oil composition of skin. Replenishing water is an essential work for comprehensive oil control. Many people think that moisturizing and hydrating can be ignored for oily skin, but actually oily skin can't escape the phenomenon of water shortage. Replenishing water to the skin in time can make the skin reach the best state of water-oil balance.
Step 5: Add vitamin B2.
Excessive skin oil secretion is caused by the lack of vitamin B2 in the body. The first step to get rid of grease is to start from the root: vitamin B2 supplement. Eat foods rich in vitamin B2, such as laver, celery, carrots, animal liver and kidney, oranges, etc.