Alpha hydroxy carboxylic acids, commonly known as AHAs, are a class of carboxylic acids characterized by a hydroxy group situated one carbon atom away from the acid group. This specific structural feature sets them apart from beta hydroxy acids, where the functional groups are separated by two carbon atoms. Among the notable AHAs are glycolic acid, lactic acid, mandelic acid, and citric acid.
AHAs are primarily derived from plant-based sources. Some of the most prevalent types include glycolic acid from sugarcane, lactic acid from sour milk, citric acid from lemons, and malic acid from apples. These acids are stronger than their non-alpha hydroxy counterparts due to enhanced internal hydrogen bonding.
In industrial applications, AHAs are used as additives in animal feed and as precursors for polymer synthesis. In the cosmetic industry, their primary use is for chemical exfoliation and skin moisturization. Products containing AHAs are marketed for their ability to smooth fine lines and wrinkles, improve skin texture and tone, cleanse pores, and enhance overall skin condition. They are also used to adjust the pH of cosmetic formulations.
AHAs promote exfoliation, or the shedding of the skin’s surface layer. The extent of exfoliation depends on the type and concentration of the AHA, its pH, and other ingredients in the product. AHAs dissolve the “glue” that holds dead skin cells together, helping them to slough off gently. This results in increased radiance, smoother texture, and fewer dark spots, making AHAs suitable for those with sensitive skin who may find physical exfoliation too harsh.
AHAs help to remove dead skin cells, resulting in smoother and more radiant skin. They dissolve the bonds between dead skin cells, making them easier to shed.
Additionally, AHAs, particularly glycolic acid, promote collagen development in the dermis. Increased collagen levels lead to fewer lines and wrinkles.
Glycolic, malic, and lactic acids are humectants that attract water to the skin, making them ideal for dry skin.
Citric acid, in particular, offers antioxidant benefits, helping to fight free radical damage and lighten dark spots.
When selecting an AHA, it is important to consider the specific type and its concentration. Glycolic acid, being the smallest molecule, delivers significant results but may require lower concentrations for sensitive skin. Lactic acid is a larger molecule, making it a good option for sensitive skin, while malic acid is even larger and less likely to cause irritation.
A good approach is to choose a product that blends lower amounts of various AHAs, as combining different acids at lower strengths can be less irritating and provide diverse hydrating benefits.
AHAs are found in a range of products from cleansers to creams. Those with sensitive skin should start with wash-off formulas to minimize exposure. Start by using AHAs once or twice a week, gradually increasing frequency as tolerated. Avoid using retinoids at the same time as AHAs and be careful when combining AHAs with beta hydroxy acids (BHAs) to prevent irritation.
Alpha hydroxy acids offer a multitude of benefits for the skin, from exfoliation and hydration to increased collagen production and antioxidant protection. By understanding how to choose and use AHAs effectively, you can achieve healthier, more radiant skin. Always follow product instructions and introduce AHAs gradually to avoid irritation. With careful use, AHAs can become a valuable part of your skincare routine.
