Dandruff or Seborrheic capitis is caused by a tiny organism of Malassezia species, most commonly Malassezia globosa. This organism lives on everyone's scalp and feeds on the natural oil that our scalp produces, called sebum. When Malassezia breaks down sebum, it creates a substance called Oleic Acid. Our skin has a protective layer called keratinocytes that protect us from bacteria, viruses, and fungi. But when there is too much oil on the scalp, Malassezia sticks to it and causes our skin to become inflamed, which leads to the shedding of the keratinocytes. This shedding causes the dry, irritated, or flaky scalp that we call dandruff.