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Alpha Hydroxy Acids
For centuries, both men and women have been looking for ways to keep their skin clear, youthful and radiant. For example, Cleopatra bathed in sour milk to soften her skin, and the ladies of the French Court applied a potion made of fermented wine to keep their skin smooth and blemish-free. Unknown to them, the positive effects which they obtained from these remedies were due to Alpha Hydroxy Acids (AHAs). AHAs are a group of naturally occurring substances found in a variety of fruits, sugar cane and sour milk. They are collectively referred to as "fruit acids." Some of the more common sources are:
Thanks to the scientific research begun by Americans Dr. Eugene Van Scott and Dr. Ruey Yu in 1974, AHAs have been shown to have therapeutic effects on a number of common skin conditions such as photoaging, acne, hyperpigmentation and dry, thickened skin. The result is a clear, soft texture and a smooth, supple look. How Can Acids Improve the Appearance of Skins With Such Different Conditions? First, we must refer back to the physiology of the skin. The skin is composed of three main layers. The lowest, the subcutaneous layer, or hypodermis, is made up of fat. The next layer, the dermis, is made of elastin and collagen, fibroblasts, nerves and vessels. The top layer, the epidermis, is made up of a living part—basal cells, melanocytes, Langerhans cells, keratinocytes—and on top, the dead cell layer (also known as the stratum corneum) made up of corneocytes. The epidermal layer gives the skin its appearance, color, suppleness, texture and health. It is the part of the skin which we can see and feel. Let us examine it more closely. Through a process called mitosis, the basal cells reproduce new cells every few days. As these cells migrate upward, they become drier, flatter and elongate to become keratinocytes. These cells produce "keratin" which serves as a protective barrier to the skin. As the keratinocytes continue to move upward, they become longer and drier, and by the time they reach the surface they are no longer alive. They are thin, dry compact cells called corneocytes. Within the stratum corneum, the keratinized cells are glued together by what is commonly referred to as "cellular cement" (ceramides, other lipids and glycosaminoglycans). As the cells become flat, dead and hardened, they become tightly packed in a "brick and mortar" pattern. As the cells reach the surface of the stratum corneum, however, this ordered pattern is often disrupted and there is a disorganized build-up of tightly packed dead cells which have a horny appearance when viewed under a microscope; thus the stratum corneum is known as the "horny layer." This process of migration and transformation from basal cell to keratinocyte to corneocyte is what gives the epidermis the ability to regenerate itself. This skin renewal process, the continuous renewing and shedding of epidermal cells, is known as desquamation. Desquamation is an ongoing process that takes about two weeks in a young person. As we age, however, this process can become slower (about 37 days in individuals over the age of 50) and even problematic with certain skin conditions. How Do AHAs Work? AHAs work within the upper dead layer of the stratum corneum by helping dissolve the cellular cement (glue-like material) which binds the thickened layer of dead cells together thus reducing the thickness of the stratum corneum. This loosening or breaking up of the outer skin layer leads to a sloughing of dead skin cells. Cellular turnover is normalized allowing the skin to become youthful once again. Dry, thickened skin When abnormal corneocyte cohesion and build-up occur, a condition known as hyperkeratinization results. This refers to the manner in which dead skin builds up abnormally as with a callous or dry, aged thickened skin. The skin feels and looks rough and its ability to retain water becomes impaired. The gentle and continuous exfoliation by AHAs of dead skin cells from the surface layers of the stratum corneum allows the epidermis to become smoother and softer, and reduces the appearance of fine lines while encouraging the cell renewal process. Photoaging Sun exposure is considered to be on eof the major factors in premature aging of the skin and can be seen as wrinkles, rough, leathery appearance and hyperpigmentation. Scientists tell us that 85% of the sun damage that manifests as we age originates from sun exposure that occurred before the age of 18. The aging of the skin slowly begins to show as the outermost dead cell layer begins to thicken, resulting in coarse skin texture and lack of elasticity. The skin may look dehydrated and feel dry to the touch. The texture appears less translucent. With consistent use of AHAs, one is able to reverse the damage done to the skin by photoaging. Acne Similarly, one of the major causes of acne is hyperkeratinization (abnormal corneocyte cohesion and build-up). Acne-prone individuals have an abnormally high degree of cellular keratinization inside the lining of pilosebaceous follicle. When the dead cells clump up together, a blockage occurs which inhibits the flow of oxygen allowing the P. acne bacteria to flourish. The result is acne. AHAs, by loosening the glue-like bonding of the corneocytes inside the follicle, allow dislodgment of the comedonal plugs. Also, through reduction of the corneocytes, follicles are prevented from being clogged, which generally inhibits the acne process. Dilated Pores Dead cells can build up around the follicle openings (pores), making them appear more prominent or dilated. By acting as a follicular cleanser, AHAs can clear the pore openings, making them smaller and more refined. Hyperpigmentation Hyperpigmentation results from the uneven deposits of melanin on the surface of the skin which appear as brown spots (age spots), freckles, melasma, chloasma and other forms of discoloration collectively referred to as dyschromia. The melanocyte cell located in the basal layer of the epidermis produces pigment-containing melanosomes which are transferred into the surrounding keratinocytes of the epidermis. The pigment is then distributed throughout the epidermis. The amino acid necessary for melanin production is tyrosine, which is transformed into melanin via the enzyme tyrosinase. Melasma and chloasma are caused by hormonal imbalances, but age spots and acne spots are the result of pigment accumulation on the skin's surface due to a build-up of dead cells (hyperkeratinization). By removing the dead cells, AHAs are able to improve the pigmented areas. Ingrown Hairs Ingrown hairs can be cause by shaving or waxing. Shaving or waxing especially of curly hairs can cause the hairs to grow back into the skin not out. AHAs can loosen the excess dead cells and free the trapped hairs. Other Functions of AHAs Moisturizers AHAs act as superb moisturizers due to their hygroscopic (water-binding) ability. They have also been shown to increase glycosaminoglycans (an intracellular substance known to bind water) similar to glycerin. Delivery Agent By thinning the dead cell layer, AHAs enhance the penetration of other ingredients used in conjunction with them. They thus act as delivery vehicles into the skin. What Can a Client Expect Upon Using AHAs? The client can expect to see a visible improvement after two to three weeks of usage in the following areas:
As the skin becomes accustomed to AHAs, clients may experience a slight tingling or redness. As dead cells of the stratum corneum are being shed, flaking or dryness may occur. Similarly a breakout of acne may occur as impurities are expelled from the follicles. Summary AHAs are non-toxic, gentle and function by reducing the overly thick outer layer of dead skin (corneocytes) responsible for many skin conditions. The exfoliation trait of AHAs combined with their water-binding ability helps to clarify problem skin, balance uneven skin tones and reduce the appearance of fine lines. The benefits are smoother, younger-looking skin. Annette Hanson Biography Annette Hanson is the founder of Atelier Esthétique, a New York State licensed esthetics school, a postgraduate facility, and a distribution center. Her professional experience in skin care spans more than 20 years as an esthetician, body therapist, salon manager, educator, and spa consultant. She is an active member of the New York State Cosmetology Association and served on The Appearance Enhancement Advisory Committee to the New York Department of State. She was instrumental in the development of the 600-hour curriculum for the New York State Esthetics License as well as the written and practical exam. She is the East Coast Chair of the California Barbering and Cosmetology Legislative Alliance and is a Director of Legislative Issues for the Esthetics Manufacturers and Distributors Alliance (EMDA).
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