What the science says.

Dandruff is associated with disequilibrium in the proportion of the major bacterial and fungal populations colonizing the scalp. PLoS One.

Finding: The dominant members of the scalp community are Cutibacterium, Staphylococcus and Malassezia. In dandruff, Malassezia restricta and S. epidermidis increase while Cutibacterium decreases.

What it means: Dandruff is linked to a shift in the balance of bacteria and yeasts on the scalp.

Characterization of the major bacterial-fungal populations colonizing dandruff scalps in Shanghai, China, shows microbial disequilibrium. Exp Dermatol.

Finding: The dandruff–microbiome findings from France were replicated in China; barrier impairment and lower levels of natural moisturizing factors were also observed.

What it means: The imbalance looks similar across different regions of the world.

Comparison of Healthy and Dandruff Scalp Microbiome Reveals the Role of Commensals in Scalp Health. Front Cell Infect Microbiol.

Finding: Cutibacterium is associated with a healthy scalp, S. epidermidis with dandruff. A healthy microbiome is rich in biotin and B vitamin pathways.

What it means: The scalp’s beneficial bacteria contribute to its nutrient balance.

Dandruff is associated with the conjoined interactions between host and microorganisms. Sci Rep.

Finding: Scalp water content is inversely related to dandruff; bacteria are more strongly associated with dandruff severity than yeasts.

What it means: Moisture and bacterial balance affect how visible dandruff is.

The diversity and abundance of fungi and bacteria on the healthy and dandruff affected human scalp. PLoS One.

Finding: Dandruff may affect up to half of the world’s population; M. restricta and Staphylococcus are more common in dandruff.

What it means: Dandruff is very common and connected to microbial balance.

Stratum corneum dysfunction in dandruff. Int J Cosmet Sci.

Finding: In dandruff, scalp lipids are disorganized, water loss is high and sensitivity to irritants is increased.

What it means: Gentle care that supports the barrier can help dandruff look less visible.

Three etiologic facets of dandruff and seborrheic dermatitis: Malassezia fungi, sebaceous lipids, and individual sensitivity. J Investig Dermatol Symp Proc.

Finding: Dandruff has three components: yeast, sebum and individual sensitivity. The yeast releases irritating fatty acids from sebum.

What it means: Oiliness, microorganisms and sensitivity together influence flaking.

Scalp Microbiome and Sebum Composition in Japanese Male Individuals with and without Androgenetic Alopecia. Microorganisms.

Finding: Men with thinning hair had higher palmitic acid in their sebum and more of the yeast that feeds on it.

What it means: In men, oiliness, sebum composition and the microbiome are interconnected.

The role of the microbiome in scalp hair follicle biology and disease. Exp Dermatol.

Finding: Hair follicles are deep niches inhabited by microorganisms; the microbiota may influence the inflammatory environment of the scalp.

What it means: The scalp is an ecosystem that reaches all the way into the follicles.

Microbiome in the hair follicle of androgenetic alopecia patients. PLoS One.

Finding: The microbiome differs in follicles from the thinning crown area; follicles from non-thinning areas resemble those of healthy individuals.

What it means: Science studies the balance around the follicle as part of hair health.

Scalp microbiome: a guide to better understanding scalp diseases and treatments. Arch Dermatol Res.

Finding: Summarizes the relationship between the scalp microbiome, dandruff and hair shedding, and discusses microbiome-targeted approaches.

What it means: The new approach in scalp care is to preserve microbial balance.

Heat-killed probiotic … ameliorates human scalp health by regulating scalp microbiome. BMC Microbiol.

Finding: With a postbiotic shampoo, dandruff and oil secretion decreased and the scalp microbiome changed.

What it means: Microbiome-focused shampoos can help dandruff and oiliness look less visible.

Clinical evaluation of paraprobiotic-associated Bifidobacterium lactis CCT 7858 anti-dandruff shampoo efficacy. Int J Cosmet Sci.

Finding: With a microbiome-based shampoo, the number of flakes decreased significantly within 4 weeks; the feeling of cleanliness and appearance improved.

What it means: With 4 weeks of regular use, flakes can become less visible.

Effects of a Postbiotic Ferment Complex on the Scalp Microbiome of Chinese Women with Sensitive Scalp Syndrome. Clin Cosmet Investig Dermatol.

Finding: With a ferment complex, the microbiome profile of the sensitive scalp changed significantly within 28 days.

What it means: Fermented ingredients can help support the balance of a sensitive scalp.

Heat-treated probiotic … regulates hair scalp microbiome balance. J Cosmet Dermatol.

Finding: Over 24 weeks, the proportion of beneficial lactic acid bacteria on the scalp rose from 6.65% to 26.19%.

What it means: Microbiome-focused care can support the proportion of beneficial bacteria on the scalp.

Efficacy of Thermus thermophilus Fermentation Extract in Promoting Hair Growth and Improving Scalp Health. J Cosmet Dermatol.

Finding: With a fermented extract, scalp moisture increased, water loss decreased by 47.43% and sebum by 20%.

What it means: Fermented ingredients can help support the moisture barrier and oil balance.

Biomolecules of Fermented Tropical Fruits and Fermenting Microbes as Regulators of Human Hair Loss, Hair Quality, and Scalp Microbiota. Biomolecules.

Finding: With a fermented shampoo and lotion, hair quality improved and the microbiome profile became more balanced.

What it means: Fermented hair care is a research field focused on supporting the scalp microbiome.

The Treatment and Evaluation of Dandruff and Scalp Erythema with Fermented Salix purpurea Bark Extract. Clin Cosmet Investig Dermatol.

Finding: Fermented shampoos were well tolerated for 8 weeks and dandruff symptoms decreased.

What it means: With regular use, fermented shampoos can help dandruff look less visible.

The effects of caffeine and adenosine on the microbiome and lipidome of the scalp. Int J Cosmet Sci.

Finding: Using a shampoo reduced yeast and increased Cutibacterium on the scalp; the lipid profile changed.

What it means: Your choice of shampoo can change the scalp microbiome within a few weeks.

Bifidobacterium longum lysate, a new ingredient for reactive skin. Exp Dermatol.

Finding: In the group using a microbiome-based cream, skin sensitivity decreased and barrier resistance increased.

What it means: Microbiome-focused ingredients can help sensitive skin feel more resilient.

Prebiotic Colloidal Oat Supports the Growth of Cutaneous Commensal Bacteria Including S. epidermidis and Enhances the Production of Lactic Acid. Clin Cosmet Investig Dermatol.

Finding: The prebiotic ingredient selectively supported the growth of beneficial skin bacteria, increased lactic acid production and lowered pH.

What it means: Prebiotics can support the skin’s natural acidic balance and its beneficial bacteria.

Impact of prebiotics and probiotics on skin health. Benef Microbes.

Finding: In cosmetic formulas, prebiotics can selectively enhance the activity of the normal skin microbiota.

What it means: The goal of a prebiotic is not to destroy bacteria but to support the beneficial ones.

Prebiotic Oligosaccharides in Skin Health: Benefits, Mechanisms, and Cosmetic Applications. Antioxidants.

Finding: Summarizes studies showing that prebiotics support the skin microbiome and increase moisture.

What it means: Prebiotics are increasingly researched skin care ingredients.

Predictive Metagenomic Profiling, Urine Metabolomics, and Human Marker Gene Expression as an Integrated Approach to Study Alopecia Areata. Front Cell Infect Microbiol.

Finding: The authors suggest prebiotic and fermented approaches as a future direction in scalp research.

What it means: Prebiotics are a next-generation approach attracting attention in scalp science.

Perceived prevalence of a sensitive scalp: A worldwide study. J Eur Acad Dermatol Venereol.

Finding: 47.2% of adults consider their scalp sensitive: 48.8% of women and 44.6% of men.

What it means: Worldwide, roughly one in two people find their scalp sensitive.

Sensitive scalp: does this condition exist? An epidemiological study. Contact Dermatitis.

Finding: 44.2% reported a sensitive scalp; triggers include pollution, heat, emotions and shampoos.

What it means: Shampoo choice is among the triggers of sensitivity.

Evaluation of sensitive scalp severity and symptomatology by using a new score. J Eur Acad Dermatol Venereol.

Finding: About one third of the population reports a sensitive scalp; the most common symptoms are itching and tingling.

What it means: Sensitivity shows up as sensory complaints such as itching.

Sensitive Scalp: A Possible Association With the Use of Hair Conditioners. Front Med.

Finding: Of those with a sensitive scalp, 89% reported itching and 45% tingling.

What it means: Itching is the main complaint of a sensitive scalp; a simple routine matters.

Natural skin surface pH is on average below 5, which is beneficial for its resident flora. Int J Cosmet Sci.

Finding: Natural skin pH averages 4.7; an acidic pH helps beneficial flora stay attached to the skin, and tap water raises pH for up to 6 hours.

What it means: A mildly acidic formula is compatible with the skin’s natural pH and its beneficial bacteria.

The Shampoo pH can Affect the Hair: Myth or Reality?. Int J Trichology.

Finding: 61.8% of shampoos had a pH above 5.5; among anti-dandruff shampoos, 80.8%. An alkaline pH can increase friction, frizz and breakage.

What it means: A shampoo with a pH close to 5.5 leaves the hair shaft smoother.

Profile of irritant patch testing with detergents: sodium lauryl sulfate, sodium laureth sulfate and alkyl polyglucoside. Contact Dermatitis.

Finding: The effect of SLS on the skin barrier is still measurable on day 10; SLES is milder but detectable for up to 7 days.

What it means: Cleansers free of SLS/SLES put less strain on the barrier.

Shampoos: ingredients, efficacy and adverse effects. J Dtsch Dermatol Ges.

Finding: A shampoo’s cleansing power depends on the type and amount of surfactant.

What it means: The type of cleanser determines how gentle a shampoo is.

The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions. Skin Appendage Disord.

Finding: Satisfaction was highest with 5–6 washes per week; daily washing did not damage the hair shaft.

What it means: A gentle shampoo can be used every day.

Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. J Cosmet Sci.

Finding: Of the three oils, only coconut oil markedly reduced protein loss from hair; it can penetrate the hair shaft.

What it means: Coconut oil is an ingredient with a scientific track record in protecting the hair shaft.

Longitudinal study of the scalp microbiome suggests coconut oil to enrich healthy scalp commensals. Sci Rep.

Finding: With coconut oil, bacteria and pathways associated with a healthy scalp became more abundant.

What it means: Coconut oil can help support the balance of the scalp microbiome.

Glycerol accelerates recovery of barrier function in vivo. Acta Derm Venereol.

Finding: Glycerin accelerated barrier recovery and increased skin moisture.

What it means: Glycerin is a well-established humectant that supports the moisture barrier.

Glycerol and the skin: holistic approach to its origin and functions. Br J Dermatol.

Finding: Glycerin helps preserve skin moisture and support the barrier; it supports the skin against irritants.

What it means: Glycerin helps the scalp keep its feeling of moisture during washing.

Seasonality of hair shedding in healthy women complaining of hair loss. Dermatology.

Finding: Hair follows a yearly cycle; the proportion of hairs in the shedding phase peaks in summer, with a second peak in spring.

What it means: Seeing more hairs at the change of seasons is often part of the natural cycle.

Telogen Effluvium: A Review. J Clin Diagn Res.

Finding: The most common cause of diffuse shedding; it begins 3–4 months after the trigger.

What it means: Increased shedding months after a stressful period is common.

Frequency, severity and related factors of androgenetic alopecia in dermatology outpatient clinic: hospital-based cross-sectional study in Turkey. An Bras Dermatol.

Finding: Pattern thinning was found in 67.1% of men and 23.9% of women.

What it means: In Turkey, thinning is a common concern for both men and women.

Prevalence of male and female pattern hair loss in Maryborough. J Investig Dermatol Symp Proc.

Finding: Over the age of 80, mid-frontal thinning is seen in 57% of women and 73.5% of men.

What it means: Thinning is not unique to men.

Corticosterone inhibits GAS6 to govern hair follicle stem-cell quiescence. Nature.

Finding: A stress hormone that rises under chronic stress keeps hair follicle stem cells in the resting phase.

What it means: Stress hormones can affect the hair cycle.

The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatol Ther.

Finding: Summarizes the role of vitamin and mineral deficiencies in the hair cycle.

What it means: Hair health is also nourished from within; nutrition complements your routine.