Kojic acid is made from several different types of fungi. It’s also a byproduct when certain foods ferment, including Japanese sake, soy sauce, and rice wine.
Kojic acid inhibits and prevents the formation of tyrosine, which is an amino acid that’s needed to produce melanin. Melanin is the pigment that affects hair, skin, and eye color. Because it inhibits the production of melanin, kojic acid can have a lightening effect.
Kojic’s acid primary use — and benefit — is to lighten visible sun damage, age spots, or scars. This can result in an anti-aging effect on the skin.
In addition to skin-lightening effects, kojic acid also contains some antimicrobial properties. It may help fight off several common types of bacterial strains even in small dilutions. This can help treat acne caused by bacteria in the skin. It may also lighten scars from acne that haven’t faded yet.