Physiological Characteristics of Scalp Skin With High Sebum Production and the Impacts of Shampoo Cleansing.

BACKGROUND: The scalp has a higher sebum content than other body areas, leading to issues such as itchiness, dandruff and discomfort. In individuals with scalp seborrhoea, the relationships between sebum levels, hydration, barrier function and self-perceived scalp condition remain poorly understood. AIMS: This study aimed to explore scalp sebum accumulation and associated physiological properties, as well as to evaluate the impact of a single shampoo cleansing efficacy on sebum levels. METHODS: This study involved an Asian population with self-reported scalp oiliness and dandruff. Participants with elevated scalp sebum levels (>75 µg/cm2) completed a health questionnaire and underwent assessments of sebum, hydration, barrier function and lipid oxidative stress biomarkers. To compare physiological differences, measurements were also taken at the frontal hairline and nape. Furthermore, the effects of a single shampoo application on scalp sebum levels were evaluated. RESULTS: At baseline, the scalp exhibited higher sebum levels, lower hydration and weaker barrier function compared to the frontal hairline and nape. Scalp hydration negatively correlated with sebum levels measured in scalp pores. Hydroxyoctadecadienoic acid (HODE), an oxidative stress biomarker, positively correlated with scalp sebum. Interestingly, HODE levels also showed a positive correlation with participants' self-reported dandruff and itchiness. After single wash with a shampoo containing 0.5% piroctone olamine (PO), surface and pore sebum levels were significantly reduced, as well as HODE levels. CONCLUSION: This study underscores the significance of sebum levels and composition in scalp health among Chinese individuals, emphasizing the need for shampoos that remove excess sebum while preserving the scalp barrier.