Dandruff is triggered the fungus, Malassezia globosa. The micro-organism is a cousin of the yeast and feeds on sebum. When the globosa grows too quickly, the natural renewal of cells will be disrupted.
According to a report in ACS’ Journal of Medicinal Chemistry:
Claudiu T. Supuran and colleagues explain that dandruff involves an excessive shedding of dead skin cells from the scalp. In people without dandruff, it takes about 30 days for a crop of new skin cells to mature, die and shed. In people with dandruff, it may take only 2-7 days. Irritation by the scalp-dwelling fungus Malassezia globosa (M. globosa)
Kirsty S. Hewitson, Daniela Vullo, Andrea Scozzafava, Antonio Mastrolorenzo, Claudiu T. Supuran. Molecular Cloning, Characterization, and Inhibition Studies of a β-Carbonic Anhydrase fromMalassezia globosa, a Potential Antidandruff Target. Journal of Medicinal Chemistry, 2012; 55 (7): 3513 DOI: 10.1021/jm300203r