As the epidermal layer continually replaces itself, cells are pushed outward where they eventually die and flake off. In most people, these flakes of skin are too small to be visible. However, certain conditions cause cell turnover to be unusually rapid, especially in the scalp. For people with Dandruff, skin cells may mature and be shed in 2 - 7 days, as opposed to around a month in people without Dandruff. The result is that dead skin
cells are shed in large, oily clumps, which appear as White or Grayish patches on the scalp and clothes.
Dandruff has been shown to be the result of three required factors:
1. Skin oil commonly referred to as Sebum or sebaceous secretions;
2. The metabolic by-products of skin microorganisms (most specifically Malassezia yeasts);
3. An individual susceptibility.
4. Due to stress
Common older literature cites the fungus Malassezia furfur (previously known as Pityrosporum ovale) as the cause of Dandruff. While this fungus is found naturally on the skin surface of both healthy people and those with Dandruff, it has recently been shown that a scalp specific fungus, Malassezia Globosa, is the responsible agent. This fungus metabolizes Triglycerides present in Sebum by reacting with Lipase, resulting in a lipid by product known as Oleic Acid (OA) .OA is a fatty acid. Penetration by OA of the top layer of the Epidermis, the Stratum Corneum, results in an inflammatory response, which disturbs Homeostasis and results in erratic cleavage of Stratum Corneum cells. Rarely, Dandruff can be a manifestation of an allergic reaction to chemicals in hair gels/sprays, hair oils, or sometimes even Dandruff medications like Ketoconazole.