Over the years we have learned the most common ones, and that you may have already heard of for their cosmetic uses, such as the star of hydration: hyaluronic acid. But there are also lesser-known ones, such as lactic, maleic, mandelic, lipoic, linoleic, phytic, citric, tartaric, not to mention fatty acids and ascorbic, better known as vitamin C.
They are excellent allies to fight stains and smooth the skin, making it more uniform. They help eliminate dead cells and accelerate skin regeneration.
Here is a mini guide to understand what the main acids contained in cosmetics are and what they are for.
🌸 Hyaluronic Acid
Let's start with the most famous, powerful, natural moisturizer: hyaluronic acid is already contained in our skin where it performs a very important task: to keep it elastic, soft and luminous.
It is produced naturally by our body and its action allows us to protect, give turgor and moisturize the skin. With advancing age, however, the concentration of hyaluronic acid decreases due to the constant thinning of the superficial layers of the dermis, thus giving rise to the aging of the skin.
Hyaluronic acid has a molecular weight that makes it difficult to absorb it on the skin, the products must be combined in order to make them operate jointly to ensure the maximum degree of absorption of hyaluronic acid in the skin.
A high-performance hyaluronic acid of plant origin must be composed of different molecular weights mixed together (very low, low, medium, and high molecular weight).
The low and very low molecular weight specifically allow you to penetrate deeper, ensuring a plumping and wrinkle lifting effect that would not be possible only with high molecular weights.
The medium and high molecular weight ensure an intense moisturizing, plumping and anti-wrinkle power, giving the skin an immediate and lasting tensor effect, reshaping the facial and décolleté features.
Hyaluronic acid is used for cosmetic products mainly because of its anti-wrinkle and preventive function of skin aging.
🌸 Glycolic Acid
Glycolic acid is an exfoliating acid that is obtained from the processing of sugar cane and is perfect for renewing the skin and making it brighter and more compact. Ideal for treating all skin types (except the very sensitive one). It can be used by both young and mature skin, therefore excellent as an anti-aging. In fact, its peculiarity of having a very small molecule that manages to penetrate deep into the skin makes it perfect for renewing it, smoothing wrinkles and giving light and firmness to the complexion.
It is the best known among exfoliating acids and is also the most widely used.
It is part of the family of alpha-hydroxy acids (AHAs, also called “fruit acids”) as well as malic acid, attic acid and citric acid, present in nature but which can be easily reproduced even in the laboratory through synthesis. Precisely the natural origin and, in particular, the origin from fruit, gives it the name of “fruit acids” to this group of chemicals of which glycolic acid, together with mandelic acid, are part.
Glycolic acid is widely used in cosmetics because it has a regenerating action on the epidermis. It gives the skin a brighter and smoother appearance, as well as a more homogeneous complexion and a thinner grain.
But not only that: it is in fact also effective for reducing acne, dark spots and scars. It can be found in tonics, creams, night treatments and masks.
🌸 Salicylic Acid
Salicylic acid is an acid of plant origin that comes in the form of white crystals or crystallized powder.
It is a beta-hydroxy acid with a keratolytic action, that is, it dissolves dead cells, helping them to detach from the stratum corneum and is mainly indicated to regulate and perfect the production of sebum.
Its greatest power is, as already indicated is to be a keratolytic, capable of dissolving the stratum corneum of the epidermis without affecting the underlying cells, that is, it perfects the grain of the skin.
It is also a soothing, antiseptic and healing. All qualities that make it a star ingredient in facial scrubs. It is considered the main weapon in the routine of those suffering from pimples and impurities.
🌸 Mandelic Acid
Mandelic acid belongs to the family of alpha-hydroxy acids, better known as fruit acids, is extracted from bitter almonds and is the mildest among the exfoliating acids for this reason it acts on the skin in a delicate way.
This sweetness seems to be due to the fact that mandelic acid is one of the alpha-hydroxy acids with the largest molecule and, consequently, penetrates more slowly into the skin, thus making it less irritating and aggressive.
It is an alpha-hydroxy acid (AHA) like glycolic acid, but with the difference that it does not cause damage to sensitive skin and is able to penetrate the dermis much more easily and gently. It can be applied in any season, because it is not photosensitive.
Its smoothing and regenerating power is also indicated to soften wrinkles and revitalize the dermis, favoring the production of new collagen. It is therefore an excellent anti-aging that acts only on the most superficial part of the stratum corneum by removing dead cells.
Lightening, antibacterial, soothing and antioxidant, it serves to even out the complexion. Perfect if the skin is oily with imperfections or if you suffer from acne because it gently exfoliates purifying the skin, relieving redness and balancing the abnormal production of sebum.
Together with glycolic and lactic acid, it is used in the cosmetics sector precisely for its exfoliating and purifying properties.
🌸 Lactic Acid
Lactic acid is a substance that derives from fermentation operated by bacteria defined as lactic, such as Streptococcus, Pediococcus and Lactobacillus, on molasses, beet or sugar cane, therefore a product of exclusively vegetable derivation.
Like hyaluronic acid, it is an organic acid, so it is already found in the skin and our body also produces it, but in the free state it is also found in many plants, where it is precisely the product of fermentation operated by lactic acid bacteria.
Lactic acid is used as a regulator of the hydrolipidic balance of the skin with exfoliating, disinfectant and renewing action, for this reason it is ideal for acne-prone skin, with dark spots and wrinkles since it acts by stimulating aged and damaged skin to regenerate favoring the normal replacement of cells.
It serves to regulate the pH of the skin restoring its optimal balance and in cosmetics it is used both to acidify the formulas, it does not have a real exfoliating action but acidifying and moisturizing.
🌸 Citric Acid
Citric acid is an organic acid belonging to the category of alpha hydroxy acids (substances capable of breaking the bonds that are created between keratinocytes, favoring skin peeling) and is obtained by extraction from citrus fruits or by fermentation of sugar solutions, in the form of a crystalline white powder soluble in water.
It has skin exfoliating properties and acts as a pH regulator in cosmetic formulations.
In cosmetics, citric acid is used at concentrations normally below 1% is added to the aqueous phase of pH regulator preparations and can also be used as an exfoliating agent in combination with other alpha-hydroxy acids.
It is not so much age that determines when and how that particular acid should be used, but the condition of the skin.
Acids should be used and chosen very carefully, because acids unsuitable for your skin or mixing them in the wrong way can cause reactions, so it is always good to first seek advice from an expert dermatologist.
They must also be chosen according to your skin type and the goals you want to achieve, and applied following the specific indications.
Then there are other lesser-known acids that are mixed with exfoliating creams and lotions to increase their peeling action, such as malic acid (extracted from apples) and tartaric acid (extracted from grapes).
They are light acids because they are formed by large molecules, and therefore penetrate less deeply into the skin, remaining more on the surface. Their function is to assist the main exfoliating acid, which in most cases is glycolic.
All acids would be better to apply them in the evening, leaving them to act during the night rest. The next day it is recommended to always apply a protective moisturizer with a very high sunscreen as the skin treated with acids is more prone to irritation and sensitization that require greater hydration and protection from the sun.
In fact, some acids can be photosensitizing resulting in the appearance of spots, so always remember that acids should be introduced slowly into your skin, even on the body. Start with the use of a light peeling or exfoliating serum every two weeks.
Remember that exfoliating acids should never be applied to injured, abraded, irritated or burned skin, better to avoid use during the day and in summer, unless it is explicitly indicated on the package.