Dandruff

Dandruff is increased turnover of skin cells on the scalp, leading to large amounts of flaking, and possibly redness and itching. In people with dandruf, skin cells develop and die in 2-7 days, in contrast to a cycle of one month in people with no dandruf. It is a condition that can fluctuate depending on the season, usually becomming worse in winter. Half of the population is affected by dandruff at some point; in people older than 50 it is not very common.

There is no real cure for dandruff yet.

Causes

Three factors are required for dandruf to appear [Ro and Dawson]:

1. sebum
2. metabolic waste of skin bacteria (specifically Malassezia globosa yeast) [Gupta et al.]
3. individual susceptibility (above two combined will not necessarily cause dandruff in non-susceptible people)

M. globosa has no ability to manufacture its own fatty acids, which are essential for life, and so relies on human sebum for its source. The way it causes dandruf:

1. The fungus produces 8 types of lipase and 3 types of phospholipase enzymes, which help to break down sebum into free fatty acids and glycerol.
2. It feeds on the satirated fatty acids, while it leaves irritating unsaturated oleic acid behind. # The oleic acid then penetrates the scalp, irritates the skin and triggers faster turnover of skin cells in susceptible people.

• • This has been proven by removing all of the fungus and treating the scalp with pure oleic acid in susceptible and non-susceptible individuals. The difference between susceptible and non-susceptible individuals is unclear.

• Note: olive oil is extremely high in oleic acid, does this mean that putting olive oil on the scalp will exacerbate dandruff?
• Note 2: the fungus research seems to be mainly done by Head & Shoulders, so likely a some details of it is not revealed.