Saliva Composition: How Water, Mucin, and Enzymes Moisten Food and Initiate Digestion

Saliva is ~99% water, but its 1% solutes perform critical functions:

Key Components

• Water – Hydrates food, enables enzymatic reactions, facilitates bolus formation.
• Mucin (glycoprotein) – Creates viscous, lubricating coating; protects mucosa, eases swallowing.
• α‑Amylase (ptyalin) – Begins starch hydrolysis → maltose, maltotriose.
• Lingual Lipase – Initiates triglyceride digestion (especially important in infants).
• Electrolytes (Na⁺, K⁺, Cl⁻, HCO₃⁻) – Maintain osmolarity, buffering.
• Proteins (albumin, proline‑rich proteins) – Lubrication, antimicrobial defense, enamel protection.

Clinical Relevance

Hyposalivation (xerostomia) from aging, medications (anticholinergics), Sjögren’s, or radiation causes dysphagia, caries, oral candidiasis, and impaired digestion. Management: hydration, sialogogues, saliva substitutes, fluoride.