Alpha Hydroxy Acids & Beta Hydroxy Acids - Skin Effects

α-Hydroxy acids (AHA's) are a class of organic chemical compounds that consist of a carboxylic acid substituted with a hydroxy group on the adjacent carbon. In the case of Alpha Hydroxy Acids (AHAs) and Alpha Keto Acids (AKAs) the hydroxyl group (with AHAs) and the Keto group (with AKAs) is in the alpha position (one removed) and in the case of Beta Hydroxy Acids the hydroxy group in the beta position from the carboxyl group (two removed).

These acids may be either naturally occurring or synthetic. AHAs are well-known for their use in the cosmetics industry, as they act as common moisturising agents by absorbing moisture from the atmosphere, hence when applied topically they help increase moisture content and plasticity of the stratum corneum. They also stimulate cell desquamation by reducing corneocyte adhesion/cohesion and accelerate cell renewal within the basal layer by induction of epidermolysis, leading to the synthesis of new collagen, and hence their use as exfolients and skin smoothing agents. They often lighten "age" spots.

They are often found in products claiming to reduce wrinkles or the signs of aging, and improve the overall look and feel of the skin. They are also used as chemical peels available in a dermatologist's office, beauty and health spas and home kits, which usually contain a lower concentration. Their effectiveness is documented.

AHAs are generally safe when used on the skin as a cosmetic agent using the recommended dosage. The most common side-effects are mild skin irritations, redness and flaking. The severity usually depends on the pH and the concentration of the acid used. Chemical peels tend to have more severe side-effects including blistering, burning and skin discoloration, although they are usually mild and go away a day or two after treatment. The danger is when, through high levels, low pH and excessive exposure times, more than the dead skin layers are removed, exposing immature skin cells, blood, nerve or lymphatic systems to harmful effects of the environment.

The FDA has also warned consumers that care should be taken when using AHAs after an industry-sponsored study found that they can increase photosensitivity to the sun.

Several common AHAs include:

Glycolic acid is the most widely used of a group of chemicals compounds known as α-Hydroxy acids (AHA's) that consist of a carboxylic acid substituted with a hydroxy group on the adjacent carbon. Glycolic acid is usually manufactured from sugar cane. It is fairly well known and considered the most effective of the AHAs for cosmetic purposes. Glycolic acid speeds the turnover of the skin cells resulting in a smoother texture and healthier appearance.

Lactic acid, derived primarily from milk is considered to be milder and less irritating than glycolic acid, and is therefore considered ideal for those with sensitive skin. Its origins can be traced back to Cleopatra, who purportedly used sour milk on her skin.

Part of their effect is decreasing the "glue" that holds dead cells on the surface of the skin. Hydroxy acids reduce the thickness of the hyperkeratotic stratum corneum by reducing corneocyte cohesion in lower levels of the stratum corneum. This induces epidermolysis, which triggers an increase in cell renewal. This helps the dead cells to slough off (desquamation), speeds skin turnover, and brings to the surface a layer of smoother, softer skin.

It usually takes about eight weeks of regular use to see a significant improvement in the skin. Glycolic acid can be combined with other bleaching agents that are used in the treatment of dark spots on skin.

Products containing hydroxy acids include cleansers, moisturizers, toners, masks, age-spot removers, and other preparations.

Types of AHAs and BHAs

AHAs include:

glycolic acid - The most popular AHA
lactic acid
malic acid
citric acid
glycolic acid + ammonium glycolate
alpha-hydroxyethanoic acid + ammonium alpha-hydroxyethanoate
alpha-hydroxyoctanoic acid
alpha-hydroxycaprylic acid
hydroxycaprylic acid
mixed fruit acid
tri-alpha hydroxy fruit acids
triple fruit acid
sugar cane extract
alpha hydroxy and botanical complex

BHAs include:
Salicylic acid
Citric acid

Effective and Ineffective AHA Creams - Glycolic Cream

Research of Eugene J. Van Scott M.D. and R. J. Yu Ph.D. opened the modern era of AHA use. In 1976 they reported that glycolic acid, in specially designed formulations, helped in the treating of a scaling skin disease (ichtyosis) and in 1988 they founded NeoStrata, a company where they continue to develop novel methods for the treatment of skin problems.

Further studies by them indicated a use for hydroxy acids in skin renewal - however, their work was ignored by the skin care industry until the 1990s when alpha and beta hydroxy acids began to be incorporated into skin care products (Van Scott and Yu 1989). Later, Stiller et al conducted large-scale, placebo-controlled studies with AHAs and found they reversed premature aging caused by sun exposure. (Stiller et al 1996) Their use was soon extended to chemical peels. (Dial 1990)

Alpha hydroxy acids (AHA's) are one of the safest methods of skin renewal. Their effectiveness depends on the type and concentration of the AHA, its pH (acidity), and other ingredients in the product. AHAs become effective at concentrations of about 7% to 8% with a pH of 3.5 to 4.0. Many AHA-containing cosmetic products have very little skin renewal effects because the AHA concentrations are too low and the pH is too high. There is little evidence that concentrations below 5% have beneficial actions on skin.

Skin improvements should be apparent after four weeks of AHA treatment, but AHA therapy also helps maintain skin health and is normally continued indefinitely.

Chemical peels with stronger AHA's (40-70%) speed the process, but skin rebuilding induced by a 70% AHA chemical peel (which is costly and may cause scarring) in 3 months can be duplicated by a 7% AHA cream in 9 months.

AHAs are marketed for a variety of purposes: to smooth fine lines and surface wrinkles, to improve skin texture and tone, to unblock and cleanse pores, to improve oily skin or acne, and to improve skin condition in general. In reality, they do increase the turnover of skin cells and enhance the rebuilding of collagen and elastin plus improve the internal moisture-holding properties of GAGs and proteoglycans. With long term use, AHAs alleviate fine to moderate wrinkles, and remove many skin lesions such as weathered skin, freckling, blotchy pigmentation, sun damage, age spots, mild acne scars, benign overgrowths of skin, and flat warts. They appear to work by causing an increased skin peeling of the lesion plus an irritation around the lesion. In time the lesion becomes smaller and is replaced by normal healthy skin.

Hydroxy acids are helpful in treating oily and acne-prone skin. Persons with these conditions often see dramatic results. Blackheads, white heads and acne breakouts are caused when the hair follicles clog and trap sebum in the follicle. Removing the upper layer of skin promotes natural sebum flow to the skin.

Long Term Low Dose AHAs as Good as Short Term Chemical Peels

Reports by various skin researchers strongly suggest that long term use of AHAs give results similar to chemical peels. The key to skin renewal is a process where (1) the skin is irritated or slightly damaged by exfoliating agents (alpha hydroxy acids, beta-hydroxy acids, retinoic acid, or mildly burned by laser re-surfacing). This is followed by (2) a natural rebuilding of the skin that removes imperfections, rebuilds collagen and elastin fibers that tighten skin, and increases the amount of glycosamoinoglycans. The stronger the exfoliation or skin damage, the stronger is the skin rebuilding action. Unfortunately, strong exfoliation causes strong skin irritation with itching, burning, and pain.

Alpha Hydroxy Acid ( 7-8%, Ph=3.8 ) Effects on Skin

Effects in 3 months
Softer smoother skin
Increased moisturization
Increased moisturization
Increased glycosaminoglycans
Strong rebuilding of collagen, and elastin
Pigment more uniform
Skin imperfections reduced

Effects in 9 months: Softer smoother skin

Safety of Hydroxy Acids and Cautions

AHAs increase sun sensitivity by 13% on average but in some persons by as much as 50%. For a 50% increase in sun sensitivity, a hydroxy acid formulated with a sun protection factor of 2 would eliminate the added sun sensitivity. AHAs with concentrations of 20% or higher are skin peels (see below) and should be applied by a dermatologist or trained cosmetologists at salons.

AHAs also may increase the penetration of other chemicals used on the skin. These include vitamins, antibiotics, Retin-A, benzoyl peroxide, resorcinol, and other dermatological medications. One should be aware of this possible interaction when using AHAs along with other skin treatments.

By 1997, The US Food and Drug Administration (FDA) had received about 100 reports of adverse effects with AHAs ranging from mild irritation and stinging to blistering and burns. The FDA advises you to test any product that contains an AHA on a small area of skin before applying it to a large area. If you experience skin irritation or prolonged stinging, you should stop using the product and consult your physician.

The Cosmetic Ingredient Review Panel of the Cosmetic, Toiletry, and Fragrance Association concluded in December 1996 that AHAs are "safe for use in cosmetic products at concentrations less than or equal to 10 percent, at final formulation pHs greater than or equal to 3.5, when formulated to avoid increasing the skin's sensitivity to the sun, or when directions for use include the daily use of sun protection." For salon use products, the panel said that the products are "safe for use at concentrations less than or equal to 30 percent, at final formulation pHs greater than or equal to 3.0, in products designed for brief, discontinuous use followed by thorough rinsing from the skin, when applied by trained professionals, and when application is accompanied by directions for the daily use of sun protection."

Are Beta Hydroxy Acids Better?

BHAs include salicylic and citric acid. Some research suggests that BHAs, especially salicylic acid, may be more effective in exfoliating the lower dermal skin layers and may be less irritating. Synthetic salicylic acid has long been in dermatology for treating adult acne and removing corns on feet. Salicylic acid is lipid soluble and hence penetrates the fatty sebum produced by sebaceous glands, eliminates acne causing bacteria, and reduces the clogging of infected pores and acne.

A leading dermatologist, Dr. Albert Kligman, believes that BHAs, in particular salicylic acid are better than AHAs for anti-aging and for skin exfoliation. Professor Kligman is well known in Dermatology for his research on the anti-aging actions of retinoic acid (Retin-A). Results from Dr. Kligman's laboratory found that the outermost stratum corneum layer is renewed after applications of salicylic acid.

What makes BIOSKINCARE Far Better For Your Skin?

BIOSKINCARE is unique in that it significantly strengthens the walls of individual cells and capillaries, and triggers the proliferation of the water holding and adhesive molecules of the skin matrix while thinning and softening the tissue of the skin. This is achieved by the action of enzymes that dissolve damaged and worn out cells and release their amino-acid components to then be used by the basal stem cells as ingredients for fibroblast proliferation and all the elements of healthy skin, including new collagen and elastin tissues.

Last modified: November 25, 2007

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