Lactic Acid Best Exfoliant Anti-Ageing Evens Skin Tone Hydration Lactic Acid at a glance Exfoliates the surface of skin Has hydrating properties Strengthens skin’s barrier Helps positively influence skin’s microbiome Lactic Acid description Lactic acid is an alpha hydroxy acid (AHA) extracted from milk. Despite such natural origins, most forms used in cosmetics are synthetic because that form is easier to stabilise and formulate with, plus it’s vegan. In a pH-correct formula (ideally a pH between 3 and 4) and in concentrations between 5 and 12%, lactic acid exfoliates on the surface of skin. It does this by breaking down the material that holds dead skin together, allowing it to shed naturally as it once did. Lactic acid also has hydrating properties (as sodium lactate, it is part of skin’s natural moisturising factor, or NMF). In addition to these benefits, lactic acid strengthens skin’s barrier by encouraging it to make more ceramides, a key component of healthy skin. It also strongly influences skin’s microbiome, helping to keep its first line of defence strong by positively interacting with a neuropeptide in skin’s surface known as Substance P, resulting in quick diffusion of signs skin is stressed. Like glycolic acid (another popular AHA), it helps brighten an uneven, dull skin tone. Related ingredients: AHA