Alpha hydroxy acids, known as fruit acids , are acids used to promote exfoliation of the skin. Exfoliating treatments that use alpha hydroxy acids are called peeling (from the English to peel, to peel).
Chemical peelsperform akeratolytic action, they act on the desmosomes which are the junctions of the keratinocytes of the horny. Acids reduce the cohesion of desmosomes, promoting the detachment and removal of dead cells.
The stratum corneum, the first defense barrier of the skin and crossing cosmetics, can be further divided into compact and disjoint . The compact stratum corneum is the deepest and in it the desmosomes are still active and hold the cells together. Flaking and desquamation begins in the disjointed stratum corneum, which is the most superficial portion of the skin.
The alpha hydroxy acids contained in our line Regenerating and Toning they work on the superficial layer of the stratum corneum.
ALPHA AND BETA HYDROXY ACIDS
Fruit acids are divided into two basic categories, namely the alpha-hydroxy acids and the beta-hydroxy acids, which can be extracted from natural substances or obtained by synthesis. The best known are:
- Glycolic acid: Found in sugar cane.
- Citric acid: coming from citrus fruits.
- Malic acid: found in apples.
- Mandelic acid: derived from bitter almonds.
- Tartaric acid: obtained from grapes.
- Lactic acid present in fermented milks
Among all fruit acids, the best known are glycolic acid and mandelic acid.
Glycolic acid is particularly appreciated due to the very small size of the molecule, a characteristic which makes it more easily absorbed by the skin. In addition to exfoliating the skin, it stimulates the synthesis of collagen and hyaluronic acid in the dermis and reduces discolouration .
Mandelic acid has a bulkier molecular structure and has a more delicate flaking action on the superficial layers of the epidermis (being larger than other AHAs it does not penetrate too much depth). For this reason it is suitable even for the most sensitive skin and in case of acne. A further advantage, does not have photosensitizing effects, therefore it can be used safely at all times of the year.
Among the beta-hydroxy acids, however, the most commonly used, especially in cosmetics, is salicylic acid.
THEIR EFFECTS
Fruit acids are, however, particularly appreciated and used for their characteristic action remove dead cells of the skin at a superficial level, consequently stimulating its renewal. These acids also act effectively in restoring hydration and freshness to the skin. This is why, increasingly, fruit acid molecules are used to hydrate and to prevent skin aging.
Intensity of the Exfoliating Action
Peeling with alpha-hydroxy acids can be more or less superficial or deep based on:
- to the chemical substance used and its concentration,
- to the formulation (pH), i.e. the quantity of free acid,
- to the time it remains on the skin.
One last warning before using AHAs: they increase sensitivity to the sun. Therefore, it is best to apply them in the evening and always use a broad-spectrum sunscreen during the day.