Oral Bifidobacterium Longum for Skin Barrier Dysfunction in Obesity

This clinical trial aims to evaluate the safety and efficacy of oral Bifidobacterium longum supplementation for treating obesity-induced skin barrier impairment in individuals aged 18-40 with BMI ≥30, compared to healthy controls. The study focuses on the following questions: Can oral Bifidobacterium supplementation reduce skin barrier damage (measured by transepidermal water loss/TEWL) in obese participants? Does modulation of gut microbiota with Bifidobacterium longum impact skin barrier function and systemic inflammation? Researchers will compare outcomes across two groups: * Intervention Group (Obese): Oral Bifidobacterium longum capsules * Placebo Control Group (Obese): Oral inactive Bifidobacterium longum (heat-killed) Participant Procedures: Take daily oral capsules (Bifidobacterium longum or inactive strain) for 4 weeks Undergo non-invasive skin testing (TEWL measurements) at baseline and study completion Provide blood, stool, and skin swab samples for inflammation and microbiome analyses Complete weekly check-ins to report adverse effects (e.g., gastrointestinal discomfort, skin irritation)