【微生物学】フケ症の重症度に対する細菌の影響

The balance between different species of bacteria on the scalp may affect the severity of dandruff according to a paper published in Scientific Reports this week.

Dandruff is a common scalp disorder which affects nearly 50% of the worldwide population and microorganisms on the scalp, in particular fungi, are thought to be the main cause of its development.

Menghui Zhang and colleagues investigated the relationship between physiological conditions including age, levels of sebum and the composition of microorganisms on the scalp, with the severity of dandruff in 174 samples from 59 Chinese participants aged between 18 and 60 years old. Participants were asked to wash their hair 48 hours in advance of tests, and dandruff samples were collected from eight different sections of the scalp.

The authors found that the severity of dandruff was more closely associated with the species of bacteria present on the scalp than with fungi. The most abundant species of bacteria found on the scalp - Propionibacterium and Staphylococcus - showed reciprocal inhibition of each other and affected the severity of dandruff. When dandruff was present, levels of Propionibacterium in the region had decreased and levels of Staphylococcus had increased, in comparison to a normal scalp. The authors suggest scalp sebum could act as a food source for Propionibacterium and higher levels of water on the scalp may provide a suitable environment for the growth of this species.

The authors argue that adjusting the balance of bacteria on the scalp, particularly by enhancing Propionibacterium and suppressing Staphylococcus might provide a potential solution to lessen the severity of dandruff.