Multi-targeted Delivery System Restores Scalp Microbiome to Reduce Dandruff

Read the full article in the May edition of C&T magazine.

The skin structure of the scalp is like other body parts but with some particularities. These include more hair follicles with terminal hair, vascularization and more sebaceous and sweat glands than other skin areas. These characteristics provide a favorable environment for microbial growth, which can cause scalp disorders.¹

An imbalance in scalp oil commonly starts with the excessive production of sebum that promotes microbiome dysbiosis, especially related to the fungus Malassezia spp., and impairs skin barrier function, resulting in inflammation and dandruff.² Each of these steps makes it more challenging to recover the scalp environment.

Excess sebum on the scalp is the primary cause of dandruff.¹ Sebum is produced by the sebaceous glands and forms the first line of protection for the scalp. It contains fatty acids, triglycerides, sugars, cholesterol-like lipids, wax and other organic compounds. Excessive sebum increases the growth of the fungus Malassezia spp., causing microbiome dysbiosis. This plays an important role in the inflammation accompanying dandruff since, as the Malassezia breaks down scalp sebum, it creates by-products that cause severe itching, redness and flaking of white, dead skin cells.²

Approximately 18 species of Malassezia have been described in the scientific literature. Some are commensal and play an important role in skin and scalp health but some are related to seborrheic dermatitis and dandruff phenotypes; M. globosa, M. restricta, M. dermatis and M. furfur, for example, are associated with these conditions.³

According to Mera and Yonter, M. globosa and M. restricta are the most strongly associated with dandruff.⁴ Other researchers emphasize the importance of the ratio between the two species; Saxena, et al., studying healthy versus dandruff-afflicted scalp populations, found that a lower M. restricta to M. globosa ratio was associated with a healthy scalp.⁵ Similarly, Rong Tao, et al., stated that an increased M. restricta to M. globosa ratio was associated with seborrheic dermatitis of the scalp and dandruff.⁶ Therefore, the presence and balance of these species appear to be critical considerations for scalp care therapy.

Another important factor is the integrity of the lipid matrix of scalp skin. It is known that subjects affected by dandruff show decreased levels of fatty acids, cholesterol and ceramides. This impairment in the lipid matrix induces dry skin and desquamation, triggering a vicious cycle that increases vulnerability to dandruff. Previous research has shown that improving the barrier function of scalp skin and relieving inflammation alone can result in a significant improvement in the clinical dandruff index.¹

This highlights the importance of maintaining a healthy barrier function in scalp skin, which is especially true for men – interestingly, men are more susceptible to dandruff than women because on average, they have approximately 1.5× more sebum on their scalp than women. In addition, there are fewer amounts of ceramides in the horny layer of men’s scalps, which points to the need for a special scalp care routine for men.¹

Read the full article in the May edition of C&T magazine.

References

1. Kim, S,. et al. (2021). Understanding the characteristics of the scalp for developing scalp care products. J Cosmetics, Dermatological Sciences and Applications. 11 204-216.
2. Sommer, B., et al. (2015). Identification and characterization of lipases from Malassezia restricta, a causative agent of dandruff. FEMS Yeast Research. v 15.
3. Vijaya Chandra, et al. (2021). Cutaneous Malassezia: Commensal, pathogen or protector? Front Cell Infect Microbiol. 10 614446; doi: 10.3389/fcimb.2020.614446.
4. Meray, Y., et al. (2018, Dec). Putting it all together to understand the role of Malassezia spp. in dandruff etiology. Mycopathologia. 183(6) pp 893+.
5. Saxena, R., et al. (2018). Comparison of healthy and dandruff scalp microbiome reveals the role of commensals in scalp health. Front Cell Infect Microbiol. 8 346.
6. Tao, R., et al. (2021). Skin microbiome alterations in seborrheic dermatitis and dandruff: A systematic review. Exp Derm. 30 1546-1553.