The difference between glycolic acid and fruit acid (AHA)
fruit acid (AHA) is a general term for a family of carboxylic acids. The molecule has carboxyl groups and at least one hydroxyl group, which are naturally found in various fruits, yogurt and sugar cane. Glycolic acid is a member of the fruit acid family and is the smallest molecule of α-hydroxy acid. The two are closely related, but they are also different.

Structure and Properties
The structure of glycolic acid is simply HOCH -2 COOH. Due to its small molecule, it has high water solubility and strong skin penetration, and can reach the deep layer of the skin quickly. Its acidity is relatively strong compared with others in the fruit acid family, with a pH value of about 2.5. Fruit acids cover a variety, such as lactic acid, malic acid, citric acid, etc., each with a unique structure. The structure of lactic acid is CH 🥰 CH (OH) COOH, and the structure of malic acid is HOOCCH (OH) CH 🥰 COOH. Although both contain carboxyl and hydroxyl groups, the acidity and characteristics are poor due to different carbon chain lengths and hydroxyl positions. The overall acidity of fruit acid is slightly weaker than that of glycolic acid, with a pH value of about 3-4.

Efficacy Differences
Glycolic acid has a significant effect on exfoliation and skin metabolism due to its strong permeability. It can quickly dissolve the connective substances between keratinocytes, make old waste exfoliation, make the skin smooth and delicate, stimulate the formation of collagen and hyaluronic acid in the dermis, and help reduce wrinkles and improve skin elasticity. Fruit acid also has exfoliation effect, but it is milder. Lactic acid has good moisturizing properties, which can leave water on the surface of the skin to moisturize the skin; malic acid is antioxidant, can remove free radicals, and protects the skin from damage. Fruit acid is excellent in improving uneven skin tone and brightening the skin as a whole. For example, citric acid can inhibit tyrosinase activity and block melanin production.

Applicable skin type
Glycolic acid has strong acidity, good oiliness and tolerance. Oily skin has thick stratum corneum, which is easy to clog pores. Glycolic acid can deeply cleanse and control oil secretion. However, for sensitive skin, glycolic acid may cause skin redness, tingling, desquamation and other discomforts. Fruit acid is milder and suitable for a wide range of skin types. Sensitive skin can choose low-concentration fruit acid products, such as products containing 5% - 10% lactic acid, which can improve skin quality and reduce irritation. Dry skin can use moisturizing fruit acids, such as lactic acid, for dual purposes of exfoliation and moisturization.

Glycolic acid is a kind of fruit acid, and the structure, efficacy and applicable skin type of the two are different. When choosing skin care products, you need to weigh the characteristics of glycolic acid and fruit acid according to your skin type to achieve the best skin care effect.