Exploring the Benefits of Polyhydroxy Acid for Skincare

Exfoliation is a critical component to getting glowing skin. There are plenty of options that are gentle, effective, and safer for people with sensitive or irritable skin. This article is a deep dive into an entire class of hydroxy acids - polyhydroxy acids. 

What are Polyhydroxy Acids?

Polyhydroxy acids, or PHAs, are a class of popular chemical exfoliants that are more gentle and more hydrating than other options. PHAs are similar to alpha-hydroxy acids (AHAs) and beta-hydroxy acids (BHAs) in that they work by loosening and removing dead skin cells from the surface of the skin, but they have a larger molecular structure, which means that they don't penetrate the skin as deeply as other acids. Don't overlook how important and beneficial these acids can be; just have different expectations.

Due to their larger molecular structure, PHAs are less likely to cause irritation or sensitivity than other chemical exfoliants. This makes them an excellent option for people with sensitive skin who want to reap the benefits of exfoliation without risking a damaged skin barrier.

PHAs work by dissolving the bonds between dead skin cells on the skin's surface, allowing them to be easily removed. They don't penetrate as deeply, so their surface effects are maximized. This process helps to improve skin texture and tone, brighten the complexion, and reduce the appearance of fine lines and wrinkles. In addition to exfoliation, PHAs also have humectant properties, which means that they help to attract and retain moisture in the skin.

The Benefits of Polyhydroxy Acids

It's probably no surprise to you that we love polyhydroxy acid because they are more gentle. They are still very effective, but we've found that people who take a more gradual approach (start slow and build) end up seeing better results over the long term because the other option (hit hard and fast from the start) ends up being more damaging and needing more healing time when you have to back off because you overdid it. So slow and steady wins the exfoliation race!

Some benefits of polyhydroxy acids for the face:

• Gentle and less irritating: They are milder than other exfoliants, making them a good option for those with sensitive skin or those who are new to chemical exfoliation
• Humectant properties: allowing them to help draw moisture to the skin, keeping it hydrated and plump
• Improve texture: smoothing out fine lines and wrinkles over time, improving collagen quality, improving elasticity
• Fight hyperpigmentation: They can help to brighten the skin by removing dead skin cells and allowing new, fresh skin to come to the surface.
• Suitable for all skin types, including sensitive, dry, and oily skin
• Effects on acne by helping to improve overall skin health, supporting the microbiome, and unclogging pores
• Safe to use with other products

The Risks of Polyhydroxy Acids

While they are gentler than other exfoliants, overuse can still lead to skin irritation and damage. Therefore, it's important to follow the instructions on the product and not use PHAs more frequently than recommended.

PHAs are safe for most people to use, but there are some risks to be aware of. As with any skincare product, there is a risk of skin irritation or allergic reaction. If you experience redness, itching, or burning after using a PHA product, discontinue use and discuss with your primary care provider or dermatologist. Proper patch testing should always be done before trying any new product.

Any chemical exfoliating acids can increase the skin's sensitivity to the sun, so using a broad-spectrum sunscreen with an SPF of 30 or higher when using PHA products is important.

Are PHAs Safe During Pregnancy?

The topic of skincare during pregnancy is something we get pretty annoyed about. Brands who advertise their products as "pregnancy safe" are really playing on the fears of pregnant women. Trust me, I know. I started to panic during my first pregnancy when I wondered whether toothpaste was safe! My rational brain did kick back in, though.

Always talk to your doctor for reassurance, but except for a very small number of prescription drugs that are used topically, your skincare routine is safe.

Your skin changes during pregnancy. The appearance of melasma might make you want to increase your targeted therapies against hyperpigmentation and PHAs are gentle enough that they might just be the suitable ingredient for you.

Polyhydroxy Acids Used in Skincare Products

The many benefits of PHAs can be harnessed for all skin types, even acne-prone skin. This water solubility makes PHAs suitable for various skincare formulations, including cleansers, toners, serums, and moisturizers. Here are a few of the main types of PHAs you'll see in products:

Gluconolactone

Gluconolactone is currently the most common PHA used in skincare products. It's a nice, gentle chemical exfoliant that's very hydrating. Gluconolactone is also an antioxidant, which can help protect the skin from free radicals that can cause damage and premature aging.

The hydrating (humectant) properties of gluconolactone can be attributed to its chemical structure, which contains multiple hydroxyl groups that are hydrophilic (water-loving). This helps draw moisture into the skin. As a result, gluconolactone can effectively hydrate the skin and provide a plumping effect, making it a beneficial ingredient for addressing dryness, dehydration, or dullness.

Another benefit of gluconolactone is that it's a vegan ingredient typically derived from non-animal sources, such as corn or sugar beets.

In one study comparing gluconolactone with benzoyl peroxide for treatment of acne, gluconolactone was found to have comparable results (with less side effects and irritation). So consider tying PHAs if you have acne-prone skin, especially if it's sensitive or easy to irritate. PHAs are another natural remedy for acne you might like to try. 

Lactobionic Acid

Lactobionic acid is derived from lactose, which is a type of sugar that can be found in milk and dairy products. However, most lactobionic acid used in skincare products is synthetically produced and not derived from animal sources, making it possible to still be a vegan ingredient. Brands would just need to confirm their supply chain.

In addition to its exfoliating and hydrating properties, lactobionic acid also has antioxidant and anti-inflammatory properties, which can help protect the skin from damage caused by free radicals and soothe irritation.

Galactose

Galactose is a type of sugar that is naturally found in dairy products, as well as in certain fruits and vegetables. In skin care, galactose is often used as a humectant, which helps attract and retain moisture in the skin.

While galactose can be derived from animal sources, such as milk and whey, producing it synthetically using non-animal sources is also possible. Therefore, whether or not galactose is vegan depends on the specific ingredient source used in a particular skincare product.

Galactose is not as commonly used in skin care products as other humectants, such as glycerin or hyaluronic acid. However, it can be found in some moisturizers and serums designed to provide long-lasting hydration to the skin.

Maltobionic Acid

Derived from maltose, maltobionic acid is another large molecule PHA that provides gentle exfoliation. It is unique for its ability to bind to the skin's natural proteins, creating a protective barrier and reducing transepidermal water loss. This makes maltobionic acid an excellent choice for dry, dehydrated skin.

Conclusion

Polyhydroxy acids for skin are a versatile and valuable group of ingredients, offering gentle exfoliation, hydration, and antioxidant properties. Their larger molecular size allows for slower penetration, making them suitable for sensitive skin types that doesn't tolerate AHAs and BHAs like glycolic acid and salicylic acid. Common PHAs such as gluconolactone, lactobionic acid, and maltobionic acid each possess unique attributes. Incorporating products with PHAs into your skincare routine can lead to improved skin texture, enhanced hydration, and a more radiant complexion. 

If you like to take a gentle skincare approach to your entire routine, PHAs are a great addition to other products that also focus on reducing irritation. Two great examples are Bakuchiol serums, as a gentle retinol alternative and tetrahexyldecyl ascorbate (vitamin C oil), as a gentle replacement for L-ascorbic acid. 

Check out our comprehensive guide to exfoliants if you want to learn more about all the chemical and physical options to brighten your complexion. 

References

Grimes PE, Green BA, Wildnauer RH, Edison BL. The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis. 2004 Feb;73(2 Suppl):3-13. 

Edison BL, Green BA, Wildnauer RH, Sigler ML. A polyhydroxy acid skin care regimen provides antiaging effects comparable to an alpha-hydroxyacid regimen. Cutis. 2004 Feb;73(2 Suppl):14-7. 

Kornhauser A, Coelho SG, Hearing VJ. Applications of hydroxy acids: classification, mechanisms, and photoactivity. Clin Cosmet Investig Dermatol. 2010 Nov 24;3:135-42. 

Green BA, Yu RJ, Van Scott EJ. Clinical and cosmeceutical uses of hydroxyacids. Clin Dermatol. 2009 Sep-Oct;27(5):495-501. 

Bernstein EF, Brown DB, Schwartz MD, Kaidbey K, Ksenzenko SM. The polyhydroxy acid gluconolactone protects against ultraviolet radiation in an in vitro model of cutaneous photoaging. Dermatol Surg. 2004 Feb;30(2 Pt 1):189-95; discussion 196. 

Hunt MJ, Barnetson RS. A comparative study of gluconolactone versus benzoyl peroxide in the treatment of acne. Australas J Dermatol. 1992;33(3):131-4.