The fungus that lives on every scalp
Malassezia is a yeast-like fungus present on virtually every human scalp. Under normal conditions, it feeds on sebum, the natural oil your scalp produces, and causes no visible problem. When it overgrows, it breaks down that sebum into oleic acid, a fatty acid that irritates the skin barrier, accelerates cell turnover, and produces the white or yellowish flakes recognised as dandruff. A 2007 study published in the Journal of Investigative Dermatology confirmed Malassezia globosa as the primary species responsible for dandruff globally, and identified oleic acid sensitivity as the mechanism, not bacterial infection and not dirt.
