Over to the expert
Dr Katerina Steventon is a skin scientist and columnist with experience of working at the interface of commercial, clinical and research health care sectors.
Her research interests are skin health, appearance and ageing. She specialises in difficult-to-treat skin types and innovative perspectives on consumer needs in facial skin care.
Dandruff is a concern for many people: a flaky, itching scalp that affects up to half the world’s population post-puberty. Ranging from mild to severe, the condition has a higher prevalence in men due to factors that include testosterone metabolism, a trigger of sebum production.
Symptoms can be aggravated by humidity, scratching and emotional stress.
Unilever-led research revealed how deeply the condition affects our self-esteem. When interviewed, men with dandruff complained of scalp dermatitis, but in self-evaluations did not recognise that dandruff affected their esteem or confidence.
However, this condition impacts on their behavior deeply. In contrast to self-evaluation, naïve participants looking at a muted video perceived men with dandruff to have lower confidence compared with men with a healthy scalp.
Therefore, it is important to address the causes of dandruff effectively.
Dandruff pathophysiology is not completely understood. The aetiology is multifactorial, influenced by commensal yeast, Malassezia, sebum production and individual susceptibility.
Malassezia is a strong contributory factor to dandruff formation, but its presence on healthy scalps indicates that alone it is not a cause. A healthy stratum corneum forms a protective barrier to maintain hydration of the scalp and protect against external insults.
Participants perceived men with dandruff to have lower confidence
Addressing the health of scalp skin is important. Chronic barrier damage can impair hydration, leading to atypical epidermal metabolism, which may underlie some dandruff symptoms.
In dandruff, depleted and disorganised structural stratum corneum lipids are consistent with the weak barrier, also associated with subclinical inflammation and higher susceptibility to topical irritants.
The barrier disruption may also affect susceptibility to metabolites from Malassezia. Treatments for dandruff that improve skin barrier integrity while providing effective anti-fungal activity are a promising strategy, but don’t address the full picture.
Scalp microbiome studies from different populations show the association of dandruff with bacterial and fungal dysbiosis. The scalp provides a distinct microenvironment for microbes, arising from its physiological conditions (sebum content, moisture, pH and topography).
Microbial communities confer advantageous survival through different regulatory processes, including biofilm formation and quorum sensing communication. The metabolic exchanges between the scalp and the microbiome typically support the growth of microbial biofilms in a symbiotic, commensal or pathogenic form.
A dysbiosis in the microbiome has been reported in the case of dandruff. Scalp microbiome studies have so far determined the taxonomic composition and diversity in the bacterial and fungal communities in different populations.
L’Oréal research revealed Malassezia, Propionibacterium and Staphylococcus as the prominent fungal and bacterial genera. Along with the commonly occurring Malassezia species M. restricta and M. globosa on the scalp, dandruff is associated with a yet uncharacterised Malassezia species.
The research suggests that bacterial commensals may maintain the scalp’s nutrient homoeostasis, in a similar way to the gut microbiome.
Cosmetic and pharmaceutical products for treating dandruff are often a combination of keratolytic ingredients (sulfur, salicylic acid), antimicrobials, regulators of sebum production (eg zinc) and anti-fungal drugs.
In measuring how effective anti-fungal actives are, in vitro studies should now involve not only planktonic cells, but also biofilms of dandruff-relevant strains.
Today, both ingredients manufacturers and cosmetics brands are addressing microbial issues in hair care. Solabia Saniscalp is an active ingredient from passion fruit seeds that fights against sensitivity, imbalances of the scalp and dandruff.
The new prebiotic hair and scalp range from niche brand Gallinée, meanwhile, promises to gently care for hair and balance the scalp microbiome, correcting itchiness, dandruff and even hair loss.
And it’s not only the shampoos we use, but the way we wash our hair that can contribute. Shower hoses may harbor bacteria and fungi in the form of biofilms including Malassezia, so regular use of disinfectants or replacement hoses could be beneficial.
