Who knew that a simple dip in the bath could lead to the discovery of one of skincare’s most used ingredients? Dating back to ancient Egypt, it has been said that Cleopatra used to bathe in sour donkey milk to beautify her skin. Although not clearly proven, this myth set the stage for researchers to understand and name what is produced when milk is fermented: lactic acid. A chemical now known to the world of cosmetics, its uses are bountiful, specifically in the art of exfoliation.
Lactic acid is a chemical created when the body breaks down glucose and other carbohydrates for energy. This acid is able to help the body gain the energy it needs when it over exerts itself during exercise or daily life. However, lactic acid is not only found in the body but in the food we consume as well.
Lactic acid is an organic acid made by bacteria when food goes through fermentation. There are many foods that can create lactic acid through fermentation, including: yogurt, cheese, kimchi, and sauerkraut. It is also used in the food industry as a flavor enhancer, additive, and preservative. This acid is versatile in its benefits ranging from gut health to skincare. In terms of the body, when consumed in food, lactic acid has probiotic benefits that aid in digestive health.
In terms of skincare, lactic acid was first extracted from milk in 1780 by Swedish chemist Carl Wilhelm Scheele. This experiment gave rise to more research in the use of lactic acid in skincare. Through this, lactic acid has evolved into many forms, primarily utilized in chemical peels. Classified as an alpha-hydroxy-acid (AHA), lactic acid is a gentle and safe exfoliant that works to eliminate dead skin cells – in turn hydrating the skin, adjusting pH, and reducing hyperpigmentation. Some other natural AHAs are derived from fruits and sugarcane in the form of citric acid and glycolic acid. As a popular ingredient used in multiple cosmetic products, lactic acid can be found in brands such as The Ordinary, Versed, Sunday Riley, and Paula’s Choice. It comes in the form of cleansers, toners, masks, and serums in varying dosages, with it being used as a pure exfoliant the most common. As it is an exfoliant, it is imperative to use sun protection afterwards as well.
Lactic acid is a key exfoliant used across the skincare industry to this day. With its origins dating back almost 3000 years ago, a dip in a milk bath was able to open the possibilities of foods’ uses, unlocking a new ingredient loved by consumers far and wide for its wondrous effects on the skin.