Why Saliva Matters

Saliva, often overlooked as a simple bodily fluid, plays an essential role in maintaining the health of the oral cavity and thus the entire body.

In this blog post, we will delve into the important components of saliva that will help you understand the many different ways in which saliva is essential for oral and systemic health.

Keep reading to learn about the importance of saliva!

What Is Saliva?

For starters, let’s define saliva and discuss where it comes from and what it is made of.

The autonomic nervous system (ANS) — the part of the nervous system that controls the automatic functions of the body needed to survive — controls salivation [9].

There are two divisions of your ANS responsible for salivation [9]:

Sympathetic nervous system - responsible for the body’s “fight-or-flight” response
- Stimulation of the sympathetic nervous system produces more viscous (thick) saliva, which contributes to a dryer oral cavity
Parasympathetic nervous system - responsible for the “rest-and-digest” body processes
- Stimulation of the parasympathetic nervous system produces more watery saliva, which helps with chewing and swallowing food more easily

More specifically, saliva is produced and excreted from major and minor salivary glands found throughout the oral cavity. There are three pairs of major salivary glands — the parotid glands, the sublingual glands, and the submandibular glands — and approximately 600 to 1000 minor glands [1].

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The major salivary glands contribute to 90% of total salivary secretions; Minor salivary glands contribute to the remaining 10% [9].

Of the major salivary glands, the parotid gland is the largest and provides approximately 50% of total saliva volume [1].

Together, the major and minor salivary glands produce about 0.5 to 1.5 liters (2 to 6.3 cups) of saliva per day in most adults [9].

The cells of salivary glands are in clusters called acini [8].

These cells produce secretions, or saliva, which flow out of the acinus into collecting ducts and are subsequently released into the oral cavity [8].

Salivary Composition

In terms of its makeup, saliva is composed of various substances including water, electrolytes, mucus, enzymes, and antibodies. Each of these components has a unique function that contributes to the overall function of saliva [5].

Overall, saliva is 99% water and 1% proteins, electrolytes,

and other substances [9].

Water moistens and lubricates the mouth and protects it from infection by washing away bacteria and other harmful substances [5].

Electrolytes [5]

Electrolytes are minerals in saliva that play an important role in maintaining the proper balance of fluids in the body, which are critical for normal cellular and muscle functions.

The electrolytes found in saliva include the following

Sodium and chloride - Involved in regulating the body's water balance and maintaining blood pressure
- The most abundant electrolytes in saliva
Potassium - Helps regulate nerve and muscle function
Bicarbonate - Important for neutralizing acids in the mouth and preventing tooth decay and gum disease
Calcium - Helps to strengthen the teeth and prevent tooth decay
Magnesium - Involved in bone formation and maintenance

Host-defense peptides [9] - Peptides are the building blocks of proteins

Salivary host-defense peptides are part of the body’s immune system in that they have important roles in the body’s response to infection and inflammation.

Proteins

A few of the most prevalent proteins in saliva include the following:

Proline-rich peptides (PRPs) [9] - A large family of salivary proteins that the parotid and submandibular glands produce

PRPs make up nearly 70% of the total protein of saliva
Acidic PRPs, for example, bind to a substance and form a biofilm on your teeth called the dental pellicle — learn more about biofilm formation here

Mucins [5]

Mucins, a large protein, are viscous and gel-like substances that help lubricate and protect the mouth, throat, and gastrointestinal tract.

Mucins impact several functions of saliva

Help moisten food, making it easier to chew and swallow
Provide a barrier between the acidic environment of the stomach and the delicate tissues of the esophagus
Play a crucial role in protecting the body from harmful bacteria, viruses, and other pathogens
Contain antibodies and enzymes that help to fight off infections
Trap and remove foreign particles, such as dust and pollen, from the respiratory tract

The amount and consistency of mucus in human saliva can vary depending on a person's health status, lifestyle factors, and environmental conditions.

Excessive mucus production can be a symptom of various health conditions such as allergies, sinus infections, or respiratory infections, and may require medical attention.

Enzymes [5]

Enzymes are specialized proteins that help to catalyze chemical reactions in the body that help break down carbohydrates, fats, and proteins in food, making them easier to digest.

The major enzymes present in saliva include the following

Amylase - Breaks down complex carbohydrates in a process that is important for the production of energy in the body
Lipase - Breaks down fats into smaller fatty acids, which are used for energy production and the synthesis of cell membranes
Protease - Breaks down proteins into smaller amino acids, which are used for the synthesis of new proteins in the body

Antibodies [5]

Antibodies are specialized proteins produced by the immune system in response to foreign substances such as bacteria, viruses, and other pathogens. They help neutralize pathogens that enter the oral cavity, which means they play an important role in the defense against oral infections such as tooth decay and periodontal diseases.

Saliva also contains other organic components such as glucose (sugar), urea (a waste product), cortisol (stress hormone), sex hormones like estrogen and testosterone, and substances that are specific to blood types [9].

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Being aware of the 'hidden' elements in saliva is essential to understanding the significant roles that saliva plays, not just in the oral cavity, but throughout the entire body.

Benefits of Saliva

So, now that we know what is in saliva, let’s discuss the benefits it provides.

The most recognized functions of saliva include lubrication, digestion, and the defense against infections. However, it also plays a significant role in regulating the pH of the oral environment and neutralizing acids, which is critical for oral and systemic health.

Benefits of Saliva

Cleansing properties - Saliva helps wash away food particles, bacteria, and debris from the mouth, reducing the potential for plaque buildup on the teeth and gums
Lubrication - Saliva keeps the mouth moist, which is necessary for speaking, swallowing, and eating comfortably
Antibacterial properties & protection - Saliva acts as a barrier against harmful bacteria, viruses, and fungi that can cause oral infections and cavities
Digestion - Saliva contains enzymes that help break down food, starting the digestive process right in the mouth
Taste - Saliva helps to dissolve food molecules and brings them into contact with taste receptors on the tongue, which sends signals to the brain to create the perception of taste [5]
- Saliva contains proteins that can bind to certain food molecules and enhance their taste

A protein called gustin enhances the taste of sweet and sour flavors, while another protein called statherin enhances the taste of salty flavors [5].

Tissue Repair - Saliva is rich in growth factors and proteins that promote tissue repair by encouraging cell growth and repair, helping to restore gum health faster
pH Balance - Saliva helps neutralize acids in the mouth through its buffering capacity, thus reducing the risk of tooth decay by supporting demineralization
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As you can see, saliva is important for the health of both the teeth and the oral mucosa, which in turn impacts the systemic health status of several body systems as discussed in previous blog posts — find more information here.

Disease-Promoting Characteristics of Saliva

While saliva is important in maintaining a healthy mouth, there are circumstances we must be aware of with saliva that also contribute to harmful side effects and disease formation.

A predominant state of dysbiosis related to saliva is known as

xerostomia, or dry mouth.

Xerostomia is a condition where salivary glands do not produce enough saliva. The etiology of xerostomia is multifactorial, and it leads to several symptoms and adverse health outcomes.

As a summary, xerostomia decreases oral pH, which supports the growth of pathogenic bacteria and their ability to mature and multiply. From the increased presence of pathogenic pathogens, a person’s risk of developing oral diseases increases significantly.

For review, there are nine distinct regions within the oral cavity that house unique biome communities. as discussed in this blog post.

The oral biome regions [10] — and potential side effects of xerostomia — include the following

Palatine tonsils - tonsil stones, enlarged tonsils
Tongue dorsum - hairy tongue, cracked and/or fissured tongue, burning tongue syndrome
Throat - chronic cough, difficulty swallowing and/or speaking
Attached gum - increased gingival inflammation and bleeding
Hard palate - oral thrush, challenges with dentures
Buccal mucosa - difficulty eating and/or speaking
Supragingival and subgingival tooth structures - increase in inflammation and diseased states
Saliva - overall feeling of dry oral tissues, decreased cleansing effects, decreased oral pH, increased caries rate

Although it’s considered one of the nine individual regions of the oral microbiome, saliva significantly influences all nine unique biome regions located within the oral cavity, and all of the elements of saliva discussed in this blog post play a crucial role in shaping the composition and health of the oral microbiome.

As a licensed healthcare provider, my favorite product to recommend to alleviate xerostomia is Periovance Dry Mouth Oral Moisturizing Gel.

Overall, changes to optimal salivary parameters contribute to oral dysbiosis within each of the nine oral regions, which increases a person’s risk for developing oral diseases such as dental caries, periodontal disease, oral candidiasis overgrowth (i.e. thrush), and more.

If you experience any symptoms associated with xerostomia, it’s important to talk with your healthcare provider to adequately address them and to prevent the development or progression of diseases.

Salivary Biomarkers

Through decades of research, and because it houses so many unique elements, saliva has been identified as a bodily fluid that can be reliably tested to identify both oral and systemic disease biomarkers such as those listed below.

Proteomic biomarkers [5]

Proteins or peptides that are found in saliva and can be used to diagnose, monitor, or predict the outcome of disease

Inflammatory biomarkers
Cancer biomarkers
Infectious disease biomarkers
Neurological biomarkers

Genetic biomarkers [5]

Genetic variations or mutations found in DNA or RNA that can be used to predict the risk of developing a disease or to monitor disease progression

Inherited disease biomarker
Cancer biomarkers
Pharmacogenomic biomarkers
Behavioral biomarkers

Metabolic biomarkers [5]

Specific metabolites found in saliva and are used as indicators of disease or physiological conditions.

Metabolites are small molecules that are involved in the body's metabolic processes, including the breakdown and synthesis of nutrients and other molecules.

Glucose biomarkers
Lipid biomarkers
Inflammatory biomarkers
Neurotransmitter biomarkers

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In terms of oral health, ask your dental providers about salivary diagnostics.

Salivary testing is one of my favorite advancements of modern dentistry!

Because the biological onset of periodontal diseases can be identified well before clinical manifestations appear, use of in-office and at-home screening tests for early detection of oral diseases is quickly becoming the new standard of care.

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In addition to the age-old assessments of pocket depths and radiographic bone levels (as discussed further in this blog post), salivary testing provides valuable insight into the subclinical disease parameters occurring for each patient. Detection of these subclinical markers allows for earlier intervention and individualized care plans, thus resulting in more ideal long-term outcomes of treatment.

There are several companies dental offices are able to work with to provide patients with simple, non-invasive, in-office tests that identify pathogens and diseased states and provide a subsequent path toward treatment and resolution.

The results of these tests can — and should — be shared with all members of a patient’s healthcare teams.

Interdisciplinary care is essential for optimal systemic health!!

As you can see by the length of this post, saliva holds many important factors in identifying and establishing health. So many that I’m working on creating additional blog posts discussing other important aspects of saliva such as how it’s impacted by mouth breathing — check back soon for more reading fun!

For now, just remember that, although it may seem insignificant, saliva plays critical roles in many body functions including eating and speaking; digestion; maintenance of bacteria, virus, and fungal loads; and more.

Talk soon,

Liz Laney, BSDH, RDH

Oral-Systemic RDH & Educator

Have questions about periodontal disease and systemic health or want to know more? Check out the forum and start a conversation!

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