Scalp: What is Hyperseborrhea?

The sebaceous glands are exocrine glands located in the dermis responsible for the production of sebum. This is a complex mixture of lipids that plays a crucial role in protecting the scalp and skin in general. Indeed, it forms a barrier, the hydrolipidic film, which protects the scalp from external aggressions (dehydration, pollution, UV rays...). Sebum also ensures the hydration of the hair. Once synthesized, it gradually flows along the hair fibers and coats them, thus ensuring their moisturization. However, due to hormonal imbalance or an external cause, it can happen that the sebaceous glands undergo an imbalance and produce an excess of sebum: this is referred to as hyperseborrhea.

This excess sebum on the scalp leads to several problems, ranging from minor to severe. The first issue that comes to mind is a social inconvenience. Indeed, hyperseborrhea gives hair a greasy and dirty appearance, and tends to flatten it. This unattractive look of the hair can be a source of insecurity for those affected. They then react by increasing their number of weekly shampoos. However, this is a misguided solution because, when the scalp is washed too frequently, it can feel attacked. In defense, the sebaceous glands increase sebum production: this then creates a vicious cycle.

Furthermore, an accumulation of sebum on the scalp creates a favorable environment for bacterial colonization and parasitic infestation. This can contribute to the appearance of dandruff, which are small dead cells ranging in color from white to yellow. Indeed, studies have shown a link between the fungus Malassezia and the presence of dandruff. These yeasts have lipase activity, meaning they hydrolyze the triglycerides in sebum and release unsaturated fatty acids. These are metabolites that cause abnormal differentiation of keratinocytes, leading to abnormalities in the stratum corneum, such as parakeratosis and dandruff. Finally, some unsaturated fatty acids released by Malassezia produce prostaglandins, pro-inflammatory mediators that can cause scalp itching.