Exfoliation

Treating badly flaking skin

The modern history of acid exfoliants doesn't just start with the search for a brighter complexion. In 1974, dermatologist Eugene Van Scott and researcher Ruey Yu published work on alpha-hydroxy acids, or AHAs, in ichthyoses. These diseases are notably accompanied by an accumulation of scales. Their observations show that some of these compounds modify keratinization, the process that results in the formation of the stratum corneum.

This starting point helps to understand the benefit of acids: they make it possible to act on the way in which the surface cells detach, without having to remove them by strong friction. This does not mean, however, that healthy skin suffers from the same problem as skin affected by ichthyosis. The results obtained in a skin disease open up avenues; they are not enough to make an exfoliant necessary in every bathroom.

Tests on the appearance of the skin

In the 1990s, research also focused on skin marked by the sun. A trial published in 1996 compared creams containing 8% glycolic or lactic acid in their base without these active ingredients for twenty-two weeks, in 74 women. The authors report a modest improvement in certain signs of photoaging. This work provides more concrete arguments for the cosmetic uses of AHAs, while reminding us that results take time.

However, the word “exfoliant” covers very different products. A cream studied for several months, a cleanser rinsed after a few moments and a peel carried out in the office do not expose the skin in the same way. The results of a test are therefore not automatically transferred to each bottle that displays the same acid. The formula and conditions of use are part of the result, just like the name of the ingredient.

The search for better tolerated formulas

PHAs, like gluconolactone, then expand the possibilities. In 2004, a study explored the effects of this molecule in an experimental model of UV damage and measured the response of human skin to exposure. This work is part of a search for properties complementary to exfoliation. They do not make gluconolactone a sunscreen and cannot promise the same effects with any product that contains it.

The literature now describes several families of hydroxy acids, with different uses and tolerance profiles. This leaves more choice, but also makes labels less easy to compare. When choosing a treatment, the most useful guideline ultimately remains quite simple: what it can improve on your skin, how it is used and the comfort it leaves after several applications. The most well-known asset is not necessarily the one you need.