Effects of fermented tea seed oil on the skin lipid barrier and microbiome of sensitive skin

Objective Sensitive skin is typically characterized by dryness, reactivity and inflammation, often associated with a compromised skin barrier and an imbalanced microbiome. This study aims to investigate the effects and mechanisms of fermented tea seed oil in improving sensitive skin, particularly focusing on the skin lipid barrier and microbiome. Methods Tea seed oil was fermented using biotechnology, and its lipid components were analysed both before and after fermentation. A double‐blind, randomized, half‐face controlled clinical trial was conducted on 25 Chinese young women with sensitive skin. Participants used a moisturizer containing 5% fermented tea seed oil or a base moisturizer for 4 weeks. Non‐invasive methods were used to measure physiological parameters. Ultra‐performance liquid chromatography‐quadrupole time‐of‐flight mass spectrometry (UPLC‐QTOF‐MS) and high‐throughput gene sequencing technologies were employed to analyse skin lipids and the microbiome. Results Fifty‐three differential lipids were identified by comparing the lipid profiles of tea seed oil before and after fermentation. The most significant increase was observed in DHA‐CoA, which has the potential to improve skin lipid metabolism and enhance the skin barrier. The participants showed significant improvements in skin hydration, redness reduction and facial wrinkles. Lipidomics analysis revealed notable changes in the skin lipid profile before and after treatment, with 41 and 15 differentially expressed lipids identified in the test and control groups, respectively. Microbiome results indicated no significant alterations in the diversity or abundance of skin microbiota after treatment. Nevertheless, the composition of the skin microbiota demonstrated a beneficial shift, with Propionibacterium acnes being suppressed while Streptococcus increased. These microbial changes are associated with skin barrier repair as well as sensitivity and inflammation. Conclusion Fermented tea seed oil demonstrates notable clinical benefits for sensitive skin. It effectively regulates lipid metabolism and the composition of skin microbiota, thereby strengthening the lipid barrier and reducing the risk of potential inflammation. The increased presence of DHA‐CoA in the fermented tea seed oil may serve as a key molecular contributor to its improved reparative efficacy.