Article by Cathy Chi.
The skincare industry offers a vast array of products. Skin exfoliation, removing dead skin, can be done physically or chemically. Chemical exfoliation, popular in beauty routines, offers products from various brands, catering to different budgets. By applying certain ingredients on the skin the same effect can be obtained without the harsh rubbing movement. Over the years this method has advanced greatly and has become a regular step in the beauty routines of many. Different brands, varying from low to high price ranges, are now offering products for chemical exfoliation instead of physical scrubbing.
Hydroxy Acids in chemistry
Hydroxy Acids, including AHAs (Alpha-Hydroxy Acids) and BHAs (Beta-Hydroxy Acids), are commonly used in chemical exfoliation. These acids are characterized by a Carboxylic Acid group and a Hydroxy group in their molecules. Carboxylic Acid groups, like those found in acetic acid in vinegar, and Hydroxy groups, like those in ethanol, are common in various compounds. AHAs such as glycolic and lactic acid exfoliate by promoting cell turnover, resulting in smoother and brighter skin. Meanwhile, BHAs like salicylic acid penetrate pores, dissolve excess sebum, and unclog them, making them particularly effective for acne-prone skin.
When a compound contains both a Carboxylic Acid and a Hydroxy group, it forms a Hydroxy Acid (see below).
AHA and BHA
In AHA and BHA, “Alpha” and “Beta” designate the positions of the Hydroxy group concerning the Carboxylic Acid group in their chemical structures. Molecular diagrams in chemistry often illustrate carbon structures with various attached groups. The Alpha position is the carbon directly next to the Carboxylic Acid group, while the Beta position is one carbon further away from it.
Hydroxy Acids in skin care
Now that we grasp the characteristics of AHAs and BHAs, let’s explore some specific Hydroxy Acids and their roles in skincare.
AHAs
AHAs typically comprise small molecules that readily dissolve in water and deliver anti-aging benefits to the skin. Examples include Glycolic acid, the smallest AHA, and slightly larger Lactic acid.
Both acids demonstrate skin exfoliation and stimulate cell renewal. This process allows newly generated cells to surface, enhancing skin firmness, thickness, and hydration, potentially reducing fine lines or wrinkles.
BHAs
Salicylic acid (SA) and Lipohydroxy acid (LHA) are commonly marketed as BHAs, despite researchers disputing their classification as such due to the ring structure in their molecules. Nevertheless, cosmetic brands often associate SA or LHA with BHAs.
In contrast to AHAs, SA and LHA are oil soluble, making them useful in treating oily or acne-prone skin. They stimulate skin exfoliation and cell renewal in the deeper layers. Treatment with SA and LHA has shown to decrease the top layer and increase the deeper layer of the skin. Due to their oil solubility, they can also reduce sebum production, beneficial in anti-acne treatment.
Adding Hydroxy Acids into your routine
As we’ve seen, AHAs and BHAs serve different functions in skincare. AHAs are effective in anti-aging care, while BHAs can aid in routines for acne-prone skin. This article aims to provide insight into the benefits of AHAs and BHAs for your skin and why you might consider incorporating them into your routine.
Sources
[1] Esse Skincare. HYALURONIC SERUM. (2019).
[2] Kornhauser, A. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin. Cosmet. Investig. Dermatol. 135 (2010) doi:10.2147/ccid.s9042.
[3] Focal Point. White vinegar on wooden table top.
[4] WallpaperTag. Wine background.
[5] Green, B. A., Yu, R. J. & Scott, E. J. Van. Clinical and cosmeceutical uses of hydroxyacids. Clin. Dermatol. 27, 495–501 (2009).
[6] Smith, W. P. Comparative effectiveness of α-hydroxy acids on skin properties. Int. J. Cosmet. Sci. 18, 75–83 (1996).