A Comprehensive Review: The Bidirectional Role of Sebum in Skin Health.

Sebum plays a dual role in skin homeostasis, maintaining barrier function and providing antimicrobial defense. However, its dysregulation drives the pathophysiology of common skin diseases. This review explains that abnormal sebum secretion promotes acne vulgaris by inducing follicular occlusion and Cutibacterium acnes (C. acnes) proliferation, while altered composition impairs the epidermal barrier. Key factors such as high-glycemic diets, androgen fluctuations, and environmental conditions significantly influence sebaceous gland activity. The underlying molecular mechanisms involve inflammatory and hormonal pathways, including dysregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling. We conducted a systematic literature search using keywords related to sebum physiology and pathology. This review also discusses emerging therapeutic targets and the potential of advanced sebaceous gland models for future research. This synthesis provides a theoretical foundation for developing targeted interventions in dermatology and cosmetics.