Functions of Skin Oils (Sebum): Protection, Hydration, and More

Sebum, the skin's natural oil, is a complex lipid mixture secreted by sebaceous glands. Its essential functions:

• Barrier protection: Limits transepidermal water loss (TEWL); shields against pathogens, pollutants, allergens.
• Lubrication: Reduces friction, maintains skin suppleness.
• Antimicrobial: Free fatty acids (sapienic acid) and low pH inhibit pathogenic bacteria/fungi.
• Photoprotection: Squalene, vitamin E, and melanin precursors absorb UV radiation.
• Vitamin D synthesis: 7-dehydrocholesterol in sebum converts to pre-vitamin D₃ with UVB exposure.
• Hair conditioning: Coats hair shaft, providing shine and protection.
• Thermoregulation: Modulates evaporative cooling.
• Chemical signaling: Pheromone-like compounds may play social roles.

Dysregulation: Excess sebum → acne, seborrheic dermatitis. Deficiency → xerosis, eczema. Balanced skincare (gentle cleansing, non-comedogenic moisturizers) supports homeostasis.