The properties of saliva: Beyond digestion

Saliva is an essential liquid that performs fundamental functions for human health. Although we usually think of it only as a lubricant for chewing and swallowing food, its properties go much further.

Saliva is a clear liquid composed primarily of water (approximately 99%), although it contains a mixture of electrolytes, proteins, enzymes and other molecules. It is produced in the salivary glands, which include the parotid, submandibular, and sublingual glands, and plays an essential role in digestion, protecting teeth, controlling bacteria in the mouth, and much more.

Physical-Chemical Properties of Saliva

Saliva has various physical-chemical properties that allow it to fulfill its biological functions:

1. Goo: Its light and viscous texture facilitates the coating of food, making it easier to chew and swallow.
2. neutral pH: The pH of saliva generally ranges between 6.5 and 7.5, which helps neutralize acids produced by oral bacteria and protects tooth enamel.
3. Presence of electrolytes: Saliva contains ions such as sodium, potassium, calcium, chloride and bicarbonate, which help maintain the ionic balance and function of oral cells.
4. enzymatic activity: Saliva contains enzymes such as amylase and lipase, which initiate the digestion of carbohydrates and fats from the mouth.

Main Components of Saliva and Their Functions

The components of saliva are essential for various functions of the body. Below, we analyze some of the most important ones:

1. Water

• As the main component of saliva, water facilitates the digestion of food and helps dissolve molecules so that they can be tasted.

2. Digestive Enzymes

• Salivary amylase: Also known as ptyalin, this enzyme initiates the breakdown of starches into simple sugars.
• Lingual lipase: Helps in the breakdown of some fats, although it acts mainly in the stomach.

3. Antibacterial Proteins and Peptides

• Lysozyme: This protein has antimicrobial properties that fight bacteria and fungi, helping to maintain the balance of the oral microbiota.
• Lactoferrin: By binding to iron, lactoferrin inhibits the growth of bacteria that depend on this mineral.
• Histatins: They are proteins with antifungal properties that protect against infections.

4. Electrolytes

• Electrolytes help maintain the structure of oral tissues and regulate saliva flow. Additionally, bicarbonate, a key ion, neutralizes acids and protects against tooth enamel erosion.

Functions of Saliva in Human Health

The properties of saliva serve several critical functions:

1. Initial Food Digestion

• Thanks to enzymes such as amylase and lipase, saliva initiates the digestive process, which facilitates more efficient absorption of nutrients in the gastrointestinal system.

2. Teeth Protection

• Saliva forms a protective layer on the teeth, known as acquired filmwhich acts as a barrier against bacteria and prevents dental erosion.
• Its ability to neutralize acids helps protect enamel, preventing the formation of cavities.

3. Lubrication and Facilitation of Swallowing

• Saliva facilitates the chewing and swallowing of food, which is essential for proper digestion and to avoid irritation of the oral mucosa and pharynx.

4. Antimicrobial Function

• The antibacterial properties of components such as lysozyme, lactoferrin and immunoglobulins help control the proliferation of microorganisms in the mouth, preventing infections and contributing to general oral health.

5. Sensation and Flavor

• Saliva dissolves food and allows molecules to interact with the taste buds, allowing flavors to be distinguished.

6. Enamel Remineralization

• Saliva contains calcium and phosphate, essential elements for the remineralization of tooth enamel, helping to repair minor damage and keep teeth strong.

Saliva Related Problems: Xerostomia and Other Disorders

1. Xerostomia (dry mouth)

• Xerostomia is a disorder in which an insufficient amount of saliva is produced. It can be caused by dehydration, certain medications, autoimmune diseases, and treatments such as radiation therapy.
• Dry mouth increases the risk of cavities, oral infections and makes it difficult to digest and swallow food.

2. Excessive salivation

• Excessive salivation, known as sialorrhea, can be caused by neurological conditions, infections, or structural problems in the mouth. Although less common, it can affect quality of life and require specialized treatment.