Dandruff is a condition in which a large amount of the stratum corneum of the scalp falls off, and is commonly referred to as dandruff. In addition, because it looks like fine white rice bran, the medical term for it is pityriasis capitis.

In a normal scalp, skin cells typically migrate from the basal layer to the stratum corneum over a period of 14 days. After moving to the stratum corneum, the aged stratum corneocytes take another 14 days to fall off as small scales (dandruff). (Figure XNUMX) This phenomenon is called scalp turnover, and if your scalp is healthy, it will be naturally washed away with shampoo.

In the case of the scalp, where dandruff is diagnosed, the skin turnover cycle is accelerated due to inflammation, etc., and more scales fall off. As the amount of scale increases, the scales that are normally invisible become visible and appear as dandruff. (Figure 2)

"Dry dandruff" seen in people with dry scalp,
There is "oily dandruff" that occurs in people with oily scalps.

Dry dandruff is a type of dandruff that occurs in people with dry scalps, and is characterized by fine whitish dandruff that falls on the shoulders and other areas. Oily dandruff is seen in people with oily scalps, and is characterized by large, yellowish flakes that are sticky and stick to the nails. Dry dandruff and oily dandruff are different types, but both are caused by seborrheic dermatitis.

[Cause of dandruff: “Seborrheic dermatitis”]

Seborrheic dermatitis is a chronic inflammatory skin disease that often occurs in areas with many sebaceous glands, such as the scalp, face, chest, and groin.
This happens on the scalp and causes dandruff. If seborrheic dermatitis is a minor injury, dry dandruff is likely to appear, while if it is severe, seborrheic dermatitis may cause oily dandruff and scalp itching due to inflammation. In fact, seborrheic dermatitis is often the cause of itchy scalp.
This seborrheic dermatitis is caused by the Malassezia bacteria found in dandruff. Malassezia is a type of mold that likes lipids (sebum), and when it grows, it can cause odor and thinning hair.
In dandruff, there are fewer resident bacteria that are important for maintaining a healthy scalp, so Malassezia bacteria increases.

In addition to seborrheic dermatitis, the following causes dandruff and itching.
- Disturbed lifestyle habits such as lack of sleep and stress
・Change of seasons
・Shampoos and treatments that do not suit your skin, etc.

- Cause flow of dandruff and itching -

- Dandruff collected from the scalp observed under a microscope -

The following is an analysis of 54 cases of dandruff patients and 30 cases of healthy subjects. Looking at the amount of lipids, compared to healthy people, the amount of lipids is lower in dryness and higher in oiliness. In addition, the water content is lower in both dry and oily types compared to healthy people, and the dry type is even lower than the oily type. From this analysis result, it is clear that the scalp is dry due to dandruff.