Sebaceous Glands: Function, Sebum Production & Skin Health

Physiology of Sebaceous Glands

Sebaceous glands are holocrine glands attached to hair follicles (except on lips, eyelids, genital mucosa). They secrete sebum—a complex lipid mixture (triglycerides, wax esters, squalene, cholesterol esters, free fatty acids).

Functions of Sebum

1. Barrier & hydration: Occlusive film reduces transepidermal water loss (TEWL).
2. Antimicrobial: Free fatty acids (sapienic acid) lower skin pH, inhibit pathogens.
3. Antioxidant: Squalene, vitamin E scavenge UV-induced ROS.
4. Pheromone/odor precursor: Bacterial metabolism → individual scent.
5. Hair conditioning: Coats shaft, reduces friction, imparts gloss.
6. Thermoregulation: Minor role in lipid-mediated insulation.

Regulation

• Androgens (testosterone, DHT via 5α-reductase) – primary driver; ↑ at puberty.
• Estrogens – suppress sebum.
• Growth factors (IGF-1, EGF) – modulate gland size.
• Neuropeptides (substance P, CRH) – stress link.

Clinical Disorders

• Acne vulgaris: Hyperseborrhea + hyperkeratinization + C. acnes + inflammation.
• Seborrheic dermatitis: Malassezia metabolizes sebum → inflammatory metabolites.
• Sebaceous hyperplasia: Benign gland enlargement (elderly).
• Sebaceous carcinoma: Rare malignancy (eyelid).

Skin Care Balance

Over-cleansing strips barrier → rebound sebum ↑. Gentle cleansers, non-comedogenic moisturizers, and targeted actives (retinoids, niacinamide, salicylic acid) normalize sebum without irritation.