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New Age Attitude Toward AHAs
By: Christine Heathman
Posted: July 22, 2008, from the March 2007 issue of Skin Inc. magazine.
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AHAs are organic carboxylic acids characterized by a hydroxy group in the alpha position. They are hydrophilic because of their aliphatic and linear structure. AHAs are found naturally in a variety of species including foods and plants (citric, malic, tartaric and glycolic); animals (cells and body fluids); and microorganisms such as bacteria, fungi, viruses and algae. AHAs are involved in many metabolic processes and participate in essential cellular pathways such as the Krebs cycle and serine biosynthesis.
How they work
In the epidermis, AHAs have been reported to decrease stratum corneum (SC) cohesiveness, increase thickness of the viable epidermis and deposition of hyaluronic acid; they also induce a reversal of basal cell atypia, which causes the production of atypical skin cells.
AHAs amplify the number and secretion of lamellar bodies that are basic for barrier function in the epidermis. At higher concentrations, used mainly in clinical peeling solutions, AHAs induce epidermolysis, a renewal of the epidermal barrier. AHAs restore normal skin proliferation and are classified as antioxidants. These interesting compounds increase the rate of skin cell renewal and provide cells with a favorable environment for more normal function and probably stimulate epidermal proliferation by improving energy and redox status of keratinocytes.
AHAs applied topically are able to reduce the thickness of hyperkeratotic stratum corneum (HSC) by reducing corneocyte cohesion at lower levels of the SC. This permits efficient clinical control of dry skin, ichthyoses, follicular hyperkeratosis and other conditions characterized by retention of the SC.
In dermatologic and cosmetic use, the clinical benefits of AHAs are extremely profound: retexturization; improved skin tone and translucency; softer, smoother skin; fewer lines and wrinkles; reduction of acne lesions; and fading of age spots.