Right up there on my personal list of favorite skincare ingredients is one of the alpha hydroxy acids (AHAs): lactic acid. Not only do I enjoy using it in my personal skincare routine, I also like to use it on clients. For various reasons.

It’s quite an allrounder: it gently exfoliates, it’s helpful with hydrating the skin, it helps reduce the appearance of fine lines, wrinkles and enlarged pores. It generally also is very helpful in treating sun damage, dryness, hyperpigmentation and acne. Lactic acid is gentle yet effective enough to work on almost every skin type (unless you’re super sensitive or allergic). It’s simply amazing stuff!

What it is:

Alpha hydroxy acid (AHA) is a generic name for a group of acids that occur naturally in foods*¹ – Lactic acid, derived from sour milk (nowadays lab created), belongs to this group. Lactic acid has the second smallest molecular size of the AHAs (glycolic acid having the smallest molecular structure), and is therefore highly effective. Due to its ability to stimulate dermal and epidermal production of hyaluronic acid, lactic acid is clinically proven to positively influence hydration levels in the skin and also to diminish the appearance of fine lines and wrinkles, as a result of the “plumping effect” of hyaluronic acid.  As like other AHAs, it is also a chemical exfoliant, which explains why it is suitable for almost every skin type: mature, combination, oily and acne prone, dry and in some cases even sensitive skin (unlike some other forms of exfoliation which can be problematic for certain skin types and/or conditions).

How lactic acid works:

The fundamental benefit attributed to AHAs in general, is the ability to help the skin function “normally”, which means that they basically work in two ways, helping skin to achieve: (1) a proper rate of exfoliation, as well as (2) appropriate hydration levels.

(1) Like other AHAs, lactic acid exfoliates the skin by “breaking up” the bonds that hold the skin cells of the stratum corneum together. The result is an exfoliation mechanism that occurs in clusters of old, dead skin cells, rather than in “sheets” like with other exfoliants. The result is a thinner, more compact, better formed stratum corneum.*²

Note that the stratum corneum is the outermost layer of your skin, that contains old, dead skin cells (which are called keratinocytes). The epidermal layer underneath the stratum corneum actually becomes thicker! That is a result of the increased production of glycosaminoglycans (water-binding substances that look like little bottle brushes and are found between the fibers of the dermis, which contains the deeper layers of skin) and better collagen deposition*³.

You have probably heard of hyaluronic acid – the famous “water-trapper” in skincare ingredients. Good old hyaluronic acid is a component of glycosaminoglycans (GAG) and will be mentioned in the next favorite ingredient post 😉

The assumption that AHAs cause thinning of the skin is therefore misleading! While the stratum corneum layer does become thinner, the layers underneath it become thicker and appear plumper, leading to a diminished appearance of fine lines and wrinkles!

(2) The benefits of hyaluronic acids will be explained in the next post. For now, it’s important to note that lactic acid (and other AHAs), stimulate the skin’s production of hyaluronic acid and therefore help the skin to recover its natural moisture retention capabilities.*⁴

Important factors when using products that contain AHAs: “pH” and “concentration”

Unless your are getting a professional treatment from a dermatologist or esthetician, there are certain numbers to keep in mind. In order for lactic acid or any other AHA to work properly and do its job, the pH has to be slightly acidic. Note that the natural pH of skin is usually slightly acidic as well, it is 4.4-5.4.

The FDA gives following recommendation for safe use by consumers*⁵:

• The AHA concentration is 10% or less.
• The finished product has a pH of 3.5 or greater.
• The finished product is formulated to protect the skin from increased sun sensitivity, or its packaging instructs consumers to use daily sun protection.

I always preach to my clients about the importance of proper broad spectrum sun protection – no matter if it’s sunny or cloudy, summer or winter, outdoors or indoors. As I like to put it: “As long as there is daylight, you should wear UVA/UVB sun protection. Even when you’re staying inside.” Sunscreen is actually one of the most effective anti-aging products.

Sadly, most of the times companies don’t give you detailed information about the pH and concentration of their products. Alpha Hydrox is one of the very few. For your orientation: it is common practice for OTC products to have a concentration of up to 10% and a pH ranging between 3.8 and 4.4.

Studies have shown, that there is no correlation between increase in concentration and performance. Meaning that higher concentrated AHAs don’t necessarily lead to higher moisturization effects. In the worst case, you would only burn yourself, so try the products and be cautious when testing them. Everyone’s skin reacts differently and never ever overdo it.

A few product recommendations:

Although I would generally not spend too much money on an at-home cleanser, I make an exception when it comes to cleansers that contain acids, like lactic acid, salicylic acid or glycolic acid. Here’s a selection of products I like to use:

• “Age Resurfacing Cleanser” by Dermalogica, $41. It’s part of the Age Smart line but this is also an excellent choice for people who suffer from enlarged pores that get clogged easily. It provides a very gentle yet effective exfoliation effect and is good for mature skin, or skin with discolorations, i.e. from healing spots or sun damage. It’s quite potent though, so you may want to start with using 2-3 times a week and then gradually build it up to once daily, if needed.
• “Gentle Cream Exfoliant” by Dermalogica, $41. This is actually a mask. If you prefer a more thorough treatment, or if you have clogged pores or your skin looks dull and there is a lot of buildup on the surface, then this is an excellent option. I use it once a week (but I skip the above mentioned cleanser that day), and it really helps softening the plugs of congested pores, leaving my skin feeling soft, smooth and very clean. Don’t leave it on for longer than the recommended 10-15 minutes and never rub it in. You will turn red and flaky the next day. Believe me, done that, been there.
• “Good Genes” by Sunday Riley, $105. It’s a serum that contains a high amount of lactic acid along with other ingredients like licorice. Excellent choice for people with hyper pigmentation issues, i.e. sun spots, acne scarring.
• “Lactic Acid Plus” by Pure+simple, $60.45 (available online from Canada). Another serum-type treatment which is available in different strengths. Apply it after cleansing, before moisturizer.

Have you tried other products that contain lactic acid as an active ingredient? Let me know, I’m interested to hear.

As always, thank you for reading. I hope it was informative.

XX,

-Mirjam

 

*^{1 Source: Culp, Judith et al. (2013): Milady Standard Esthetics Advanced, Second Edition. Clifton Park, NY. P. 294.}

*^{2 Source: see above, p. 296.}

*^{3 Source: see above, p. 296.}

*^{4 Source: see above, p. 297.}

*^{5 Source: see above, p. 298.}