How Do Alpha Hydroxy Acids Work?

Despite what many cosmetic marketers claim, there aren’t a lot of anti-aging actives that work when delivered from topical applications. Retinol, maybe Niacinamide but not much else. However, alpha hydroxy acids (AHA) are one such active that works. But the exact mechanism by which they work has been unknown. At least until now.

Alpha Hydroxy Acids

First, an AHA is a class of compounds that contains both a carboxylic acid and a hydroxyl group on an adjacent carbon. Common ingredients include glycolic acid, lactic acid, and citric acid. They have been proven to treat conditions like acne, UV damage, and wrinkling. In high concentrations, they work as skin peels which can lead to temporary skin smoothing. They aren’t the most effective anti-aging ingredients but they do work.

AHA mechanism

Now, researchers think they have figured out how these thing work. Candidly, I never thought there was much mystery to how they work. I just figured an acid broke down the “glue” that held skin cells in the out mantel together and that led to exfoliation. But if it were that simple, any acid should work and they don’t. AHAs are special.

According to research published in the Journal of Biological Chemistry, AHAs work by interacting with a membrane protein in the skin cells. They tested glycolic acid and found that it enters into keratinocytes and generates free protons. The acidic conditions activates an ion channel in the cells membrane protein which leads to a flow of calcium ions into the cell which ultimately leads to cell death due to it becoming overloaded.


I wonder if these things could be made more effective if the skin lotion included some additional Calcium. Hmmm. Something for an enterprising young cosmetic chemist to try out.

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