Like glycolic acid, this is an alpha hydroxy acid (AHA) that exfoliates, stimulates collagen production, and also has moisturizing properties. It occurs naturally in sour milk products and can also be produced in a lab (our products use a lab-created version). As an exfoliator, it works by breaking down the adhesions between cells in the upper layer of skin, allowing old skin cells to slough off. Used in slightly higher doses (as in Major Fade Flash Mask), it can inhibit the activity of tyrosinase (a naturally occurring enzyme that regulates melanin production in the skin), thereby reducing abnormal pigmentation so skin looks brighter. It’s also a component of skin’s Natural Moisturizing Factors (NMFs) and can function as a humectant, leaving skin more hydrated.