Navin M. Geria, Senior Technical Advisor and Principal Doctors Skin Prescription03.01.16
Originally derived from spoiled milk and fermented apples, acids have been used to beautify skin for thousands of years. There is an acid for every skin type and concern, and most don’t burn or even exfoliate the skin. These materials improve dry skin, fine lines, wrinkles and acne. This month’s column will briefly review various acids that are currently found in many of today’s anti-aging products.
A wide variety of acid formulas are available, ranging from aesthetic to medical use. There is an art to developing acid formulations; it requires a very fundamental understanding of acids. Every acid has a specific purpose, affecting skin cells and tissue regeneration in unique ways. While some acids are gentle, others are much more intense, depending upon the pH of an acid and whether or not it is buffered. A buffered acid has a lower pH, which makes it more acidic and better able to penetrate skin to have an effect. The closer the acid gets to neutral pH (6.6-7.3), the less acidic the acid, which means, the less likely it is to be irritating and less effective on the skin, as well.
An OTC product can contain acid strength of anywhere from 0.5 to 5.0%; in contrast, professional products range in concentration from 20-70%—definitely stronger than what you can buy at a store! Professional products usually have lower pH so they penetrate skin further, however these professional products are usually administered under supervision and only stay on the skin for a few minutes. At-home products usually stay on the skin overnight or all day. Both of these product categories usually cause some skin reddening and tingling that is proportional to the strength of the acid in the product. Professionally administered products provide quick, dramatic results.
Types of Acid
There are basically four types of acids that are widely used in the global skin care industry—the exfoliators, the hydrators, the brighteners and anti-agers; here’s a brief review of each of them.
The Exfoliators
Exfoliating AHAs seep into skin cells and loosen ceramides, the glue-like substance holding cells together. Glycolic, salicylic, lactic and malic acids all fall into this category. These acids help reveal shiny newer skin cells that lie beneath the dead surface skin. Getting rid of dead skin increases cell turnover, allowing new cells to reflect light for a healthy glow. Glycolic acid is derived from sugar cane and is the most widely used acid, in levels ranging from 1-10%. Ideally, 8-10% works best to bring about real changes to skin. Glycolic acid rejuvenates skin with minimal irritation. It removes dead cells, smoothes texture, shrinks pores, lightens spots, evens out scars, reduces the appearance of wrinkles and keeps skin bright. Its small molecular size enables it to penetrate cellular walls and actively stimulate cell turnover.
Lactic acid is best for sensitive skin and fights signs of aging. It is used at strength of 4-12%. It is derived from milk. It exfoliates and softens lines and wrinkles. It is not as irritating as glycolic acid. It easily penetrates the skin because it is a small molecule. It appears in many skin care products, primarily because it provides skin hydration benefits.
Malic acid is a weaker version of glycolic acid. It is more suited to those with extremely sensitive skin. It loosens the bond that holds dead skin cells together and also provides anti-aging benefits.
Salicylic acid is a beta-hydroxy acid (BHA). It poses little irritation risk, as it is self-neutralizing. It works as an exfoliator to remove discolored and damaged skin cells. It improves tone, and produces a drying and lifting effect. Salicylic acid treats acne because it dries up blemishes by unclogging packed pores and loosens trapped dirt and oils. It stimulates desquamation, collagen and elastin production, and provides antioxidant, antiseptic and anti-inflammatory support. It works for most skin types. Salicylic acid is less irritating than AHAs, but may cause an allergic reaction in patients with aspirin sensitivities. Derived from willow bark, typical use levels range from 0.5-2.0%.
The Brighteners
Kojic, L-ascorbic, azelaic and mandelic acids all work at a deeper skin level to halt melanin production and impart a brightening effect. None of them has an immediate effect, but with regula use, over time, the skin color evens and has a hint of glow.
L-ascorbic acid is derived from vitamin C in synthetic form. It imparts antioxidant benefits, brightening skin and increasing collagen, L-ascorbic acid is the synthetic version of vitamin C and works to brighten skin while providing free-radical protection against photo-damage and elements in the environment such as pollution that damages skin. They are usually used at 10-20% active strength.
The Hydrators
These acids work at a deeper level of the skin, so that it is more hydrated. Hyaluronic acid provides a hydrating effect. It allows skin to hold on to water and is compatible with every skin types. It almost acts as a water magnet. It is the key ingredient in many moisturizers and injectable fillers. It works differently because it is a moisture magnet. It keeps everything hydrated and together. You get a plumping effect by injecting it. In the products it provides softer skin feel because it pulls moisture from the air down into the skin.
As a hydrator acid, kojic acid provides powerful protection against photo-damage and against pollution that damages skin. It is best for evening out skin color and lightening discoloration and age spots. It is usually incorporated into formulas levels ranging from 1-2.5%. It is a fungus derived from the Japanese mushrooms. Kojic acid boasts effects similar to hydroquinone. It is suitable for those who want long-term lightening without the risks that come with hydroquinone.
Finally, kojic acid works to disrupt the production of melanin to make skin look more even in color.
The Anti-Agers
This acid category includes ferulic acid, azelaic acid, retinoic acid and alpha lipoic acid. Ferulic acid is used for making new collagen in skin and stopping free radical damage. It is derived from the seeds and leaves of plants. Ferulic acid is usually combined with another ingredient such as retinol or vitamin C or E to provide supercharged protection from the sun and pollution.
Azelaic acid is best used for controlling redness and acne. Derived from grains, it is usually used at 10% strength. Because it soothes irritated skin, azelaic acid is used for calming rosacea-initiated redness, inflammation and bumps while evening out skin tone. Retinoic acid is used for acne and anti-aging purposes. It is most often used at levels ranging from .025-1%. Derived from vitamin A, it revs up collagen production, keeps pores clean, accelerates skin cell shedding and evens skin tone. Although skin flaking is an unpleasant side effect, cell turnover improves the look of skin, making it appear more youthful. Besides, flaking is usually temporary—skin will adjust.
Retinol is a vitamin A derivative. It converts to retinoic acid and is a DNA regulator. It effectively treats UV-induced aging and discoloration, assists in collagen synthesis and encourages healthy cell formation. Research has shown that retinol is capable of oxidizing to retinoic acid through enzyme activity, providing the benefits of Retin A without side effects. Most skin types tolerate retinol in topical and acid formulations. Alpha lipoic acid is best for antioxidant protection and minimizing wrinkles. Derived from plants, alpha lipoic acid is said to possess great penetrability; i.e., it can enter all parts of a skin cell and provide extreme protection against free radicals. This helps prevent damage to the skin and lifts skin’s vitamin levels of E and C back to normal, and giving skin a healthy glow.
Whether formulators are working with exfoliators, hydrators, brighteners or anti-agers, acids play an important role in many of today’s skin care products.
Navin M. Geria
Senior Technical Advisor and Principal Doctors Skin Prescription
[email protected]
Navin Geria, ex-Pfizer Research Fellow, is senior technical advisor and principal of the dermatological research company, Doctors Skin Prescription (DSP), Boston, founded by dermatologist David J. Goldberg, MD JD and plastic surgeons William P. Adams, MD FACS and Jason Pozner, MD. Geria has more than 30 years of experience in the personal care industry and was previously with Clairol, Warner-Lambert, Schick, Bristol-Myers and most recently, Spa Dermaceuticals. He has earned nearly 20 US patents, has been published extensively and has been both a speaker and a moderator at cosmetic industry events. www.dspskincare.com
A wide variety of acid formulas are available, ranging from aesthetic to medical use. There is an art to developing acid formulations; it requires a very fundamental understanding of acids. Every acid has a specific purpose, affecting skin cells and tissue regeneration in unique ways. While some acids are gentle, others are much more intense, depending upon the pH of an acid and whether or not it is buffered. A buffered acid has a lower pH, which makes it more acidic and better able to penetrate skin to have an effect. The closer the acid gets to neutral pH (6.6-7.3), the less acidic the acid, which means, the less likely it is to be irritating and less effective on the skin, as well.
An OTC product can contain acid strength of anywhere from 0.5 to 5.0%; in contrast, professional products range in concentration from 20-70%—definitely stronger than what you can buy at a store! Professional products usually have lower pH so they penetrate skin further, however these professional products are usually administered under supervision and only stay on the skin for a few minutes. At-home products usually stay on the skin overnight or all day. Both of these product categories usually cause some skin reddening and tingling that is proportional to the strength of the acid in the product. Professionally administered products provide quick, dramatic results.
Types of Acid
There are basically four types of acids that are widely used in the global skin care industry—the exfoliators, the hydrators, the brighteners and anti-agers; here’s a brief review of each of them.
The Exfoliators
Exfoliating AHAs seep into skin cells and loosen ceramides, the glue-like substance holding cells together. Glycolic, salicylic, lactic and malic acids all fall into this category. These acids help reveal shiny newer skin cells that lie beneath the dead surface skin. Getting rid of dead skin increases cell turnover, allowing new cells to reflect light for a healthy glow. Glycolic acid is derived from sugar cane and is the most widely used acid, in levels ranging from 1-10%. Ideally, 8-10% works best to bring about real changes to skin. Glycolic acid rejuvenates skin with minimal irritation. It removes dead cells, smoothes texture, shrinks pores, lightens spots, evens out scars, reduces the appearance of wrinkles and keeps skin bright. Its small molecular size enables it to penetrate cellular walls and actively stimulate cell turnover.
Lactic acid is best for sensitive skin and fights signs of aging. It is used at strength of 4-12%. It is derived from milk. It exfoliates and softens lines and wrinkles. It is not as irritating as glycolic acid. It easily penetrates the skin because it is a small molecule. It appears in many skin care products, primarily because it provides skin hydration benefits.
Malic acid is a weaker version of glycolic acid. It is more suited to those with extremely sensitive skin. It loosens the bond that holds dead skin cells together and also provides anti-aging benefits.
Salicylic acid is a beta-hydroxy acid (BHA). It poses little irritation risk, as it is self-neutralizing. It works as an exfoliator to remove discolored and damaged skin cells. It improves tone, and produces a drying and lifting effect. Salicylic acid treats acne because it dries up blemishes by unclogging packed pores and loosens trapped dirt and oils. It stimulates desquamation, collagen and elastin production, and provides antioxidant, antiseptic and anti-inflammatory support. It works for most skin types. Salicylic acid is less irritating than AHAs, but may cause an allergic reaction in patients with aspirin sensitivities. Derived from willow bark, typical use levels range from 0.5-2.0%.
The Brighteners
Kojic, L-ascorbic, azelaic and mandelic acids all work at a deeper skin level to halt melanin production and impart a brightening effect. None of them has an immediate effect, but with regula use, over time, the skin color evens and has a hint of glow.
L-ascorbic acid is derived from vitamin C in synthetic form. It imparts antioxidant benefits, brightening skin and increasing collagen, L-ascorbic acid is the synthetic version of vitamin C and works to brighten skin while providing free-radical protection against photo-damage and elements in the environment such as pollution that damages skin. They are usually used at 10-20% active strength.
The Hydrators
These acids work at a deeper level of the skin, so that it is more hydrated. Hyaluronic acid provides a hydrating effect. It allows skin to hold on to water and is compatible with every skin types. It almost acts as a water magnet. It is the key ingredient in many moisturizers and injectable fillers. It works differently because it is a moisture magnet. It keeps everything hydrated and together. You get a plumping effect by injecting it. In the products it provides softer skin feel because it pulls moisture from the air down into the skin.
As a hydrator acid, kojic acid provides powerful protection against photo-damage and against pollution that damages skin. It is best for evening out skin color and lightening discoloration and age spots. It is usually incorporated into formulas levels ranging from 1-2.5%. It is a fungus derived from the Japanese mushrooms. Kojic acid boasts effects similar to hydroquinone. It is suitable for those who want long-term lightening without the risks that come with hydroquinone.
Finally, kojic acid works to disrupt the production of melanin to make skin look more even in color.
The Anti-Agers
This acid category includes ferulic acid, azelaic acid, retinoic acid and alpha lipoic acid. Ferulic acid is used for making new collagen in skin and stopping free radical damage. It is derived from the seeds and leaves of plants. Ferulic acid is usually combined with another ingredient such as retinol or vitamin C or E to provide supercharged protection from the sun and pollution.
Azelaic acid is best used for controlling redness and acne. Derived from grains, it is usually used at 10% strength. Because it soothes irritated skin, azelaic acid is used for calming rosacea-initiated redness, inflammation and bumps while evening out skin tone. Retinoic acid is used for acne and anti-aging purposes. It is most often used at levels ranging from .025-1%. Derived from vitamin A, it revs up collagen production, keeps pores clean, accelerates skin cell shedding and evens skin tone. Although skin flaking is an unpleasant side effect, cell turnover improves the look of skin, making it appear more youthful. Besides, flaking is usually temporary—skin will adjust.
Retinol is a vitamin A derivative. It converts to retinoic acid and is a DNA regulator. It effectively treats UV-induced aging and discoloration, assists in collagen synthesis and encourages healthy cell formation. Research has shown that retinol is capable of oxidizing to retinoic acid through enzyme activity, providing the benefits of Retin A without side effects. Most skin types tolerate retinol in topical and acid formulations. Alpha lipoic acid is best for antioxidant protection and minimizing wrinkles. Derived from plants, alpha lipoic acid is said to possess great penetrability; i.e., it can enter all parts of a skin cell and provide extreme protection against free radicals. This helps prevent damage to the skin and lifts skin’s vitamin levels of E and C back to normal, and giving skin a healthy glow.
Whether formulators are working with exfoliators, hydrators, brighteners or anti-agers, acids play an important role in many of today’s skin care products.
Navin M. Geria
Senior Technical Advisor and Principal Doctors Skin Prescription
[email protected]
Navin Geria, ex-Pfizer Research Fellow, is senior technical advisor and principal of the dermatological research company, Doctors Skin Prescription (DSP), Boston, founded by dermatologist David J. Goldberg, MD JD and plastic surgeons William P. Adams, MD FACS and Jason Pozner, MD. Geria has more than 30 years of experience in the personal care industry and was previously with Clairol, Warner-Lambert, Schick, Bristol-Myers and most recently, Spa Dermaceuticals. He has earned nearly 20 US patents, has been published extensively and has been both a speaker and a moderator at cosmetic industry events. www.dspskincare.com