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Saliva is one of the most neglected factors in your oral and overall health. The normal secretion of saliva is also vital to a healthy mouth, free of cavities, and to proper digestion.
Let’s discuss the functions of saliva, the benefits of healthy saliva, and what to do if you produce too much or too little.
What is saliva?
Saliva, or “spit”, is an extracellular fluid produced by the salivary glands in the mouth. Saliva carries important enzymes that break down food particles, which is the first stage of the digestion process. It also delivers minerals and other nutrients to your teeth that teeth use to remineralize.
What is saliva made of? Saliva is made up of:
- Water (95% of the composition of saliva)
- Electrolytes (sodium, potassium, calcium, magnesium, bicarbonate, and phosphates)
- Immunoglobulins (IgA, etc.)
- Secretory mucins, lactoferrin, lysozyme, peroxidase, and other antibacterial compounds
- Nitrogenous compounds (urea, ammonia, and others)
Healthy saliva is slightly acidic, ranging from about 6-7 pH. This allows saliva to do its job of breaking down food and protecting the mouth from a buildup of bacteria.Learn More: Holy Spit: Saliva's Role in Cavities (EPISODE 22: What's the Juice Podcast with Organic Olivia)
The viscosity (thickness and flow) of your saliva changes based on your sympathetic and parasympathetic nervous system activity. This means that when you enter “fight, flight, or freeze” mode, the consistency of your saliva changes.
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Functions of Saliva
1. Clearing Food Debris
Saliva cleans away food debris in the mouth. When you have good saliva flow, food particles are less likely to collect and ferment on your teeth or other areas of your oral cavity.
Molecules in food that taste of distinct flavors must first be solubilized, or made more soluble (dissolvable) before you can actually taste your food.
Your saliva interacts with taste buds to unmask the tastes offered by different foods.
3. Beginning the Digestive Process
Chewing and swallowing begin digestion, but they would be useless without saliva.
As you chew, the saliva in your mouth binds food particles together into a “bolus,” a slippery substance that easily enters the esophagus. The enzyme amylase breaks down food particles into simpler compounds, which is the first step to digesting food.
The compounds in saliva also protect your throat and esophagus from what would otherwise irritate or damage their sensitive tissue.
4. Supporting the Oral Microbiome
Your saliva is a key factor in a proper balance of good-to-bad microbes in your mouth.
The macromolecule proteins and mucins in saliva destroy, gather (aggregate), and/or cling to certain kinds of oral bacteria. Mucins, in particular, can stop bacteria from attaching to the surfaces inside your mouth and prevent those bacteria (or fungi) from colonizing in a specific area.
These functions help maintain the oral microbiome and preventing pathogens (cavity-causing, or “cariogenic” bacteria) from taking over the mouth.
5. Lubricating the Mouth
Saliva is a seromucous coating, which means it creates a barrier in your mouth between the oral mucosa and anything that enters your mouth. One of the most vital functions of saliva is the lubrication of these surfaces.
By lubricating your mouth, saliva prevents your tongue, gums, cheeks, the floor of your mouth, and the roof of your mouth from being irritated.
Lubrication by saliva protects against:
- Proteolytic and hydrolytic enzymes in plaque (which can break down tooth enamel and lead to enamel erosion and tooth decay)
- Carcinogens from smoking and other chemicals you breathe in
- Dry mouth due to mouth breathing
Saliva is also what allows you to speak via lubrication of the oral mucosa.
6. Buffering Acids
Saliva not only gets rid of food debris that could feed bacteria that cause dental caries (tooth decay), it also buffers acids that can break down tooth enamel.
Compounds that help provide a buffer for teeth include:
- Histidine-rich peptides
- Amphoteric proteins and enzymes
Bicarbonate, in particular, spreads into dental plaque and neutralizes acids. Bicarbonate also creates ammonia, which forms amines — an additional buffer to neutralize acids.
This buffering function of saliva is almost nonexistent when the flow rate of saliva is very low. This is also referred to as “unstimulated saliva”.
A low salivary flow rate leads to the side effects of dry mouth (xerostomia), one of which is an increased risk of cavities.
7. Maintaining Strong Teeth
As part of defending teeth from cavities, saliva helps to maintain the strength of your teeth by supporting remineralization.
Your teeth are remineralized and demineralized all day, every day. Good salivary flow and proper pH (6-7) allows saliva to deliver minerals to your teeth while protecting against acids breaking down enamel.
8. Identifying Systemic Health Issues
Salivary proteins and DNA in your saliva can identify potential disease risk or the presence of existing disease.
Conditions your saliva may predict or diagnose include:
- Oral cancer
- Head and neck cancer
- Viruses, including HIV
- Fertility issues and problems conceiving
- Male-pattern baldness
- Chronic stress
- Cardiovascular concerns (high cholesterol and heart palpitations)
- Too-low body temperature
- Sleep disruptions
- Calcium absorption problems
- Premature aging
How Your Mouth Produces Saliva
Salivary glands produce and secrete saliva through cell clusters called acini. Acini secrete fluid that collects in ducts, where the balance of compounds in saliva is optimized.
These small ducts in the salivary glands all channel into larger ducts and come together into a single duct. That one submandibular duct is what sends 90% of your spit into your mouth.
There are major salivary glands in each side of your mouth:
- Parotid gland (high in your cheek)
- Submandibular gland
- Sublingual gland
Without any outside factors, a small amount of saliva is produced at all times. Additional saliva is produced when:
- You taste and chew food
- You smell certain odors
- You take medications that impact saliva
How to Maintain Healthy Saliva
To keep your saliva healthy and producing at a high rate:
- Stay well-hydrated. Experts suggest drinking half your body weight in ounces of water every day. If you weigh 150 pounds, you should drink at least 75 ounces of water each day. Eat hydrating foods, too, like celery and watermelon.
- Address seasonal and household allergies to help encourage nasal breathing and avoid mouth breathing.
- Practice good oral hygiene, including teeth brushing, flossing, tongue scraping, and oil pulling.
- Chew erythritol or xylitol gum and/or mints. These sugar alcohols increase the amount of saliva you produce and may support tooth remineralization.
- Eat foods of different textures. Eating foods that require significant chewing encourages salivary flow.
- Mouth tape every night. Mouth breathing during sleep is one of the main drivers of dry mouth.
- Use artificial saliva products like Biotene gel, which provide moisture for people who simply can’t produce enough saliva. In severe cases, your dentist may be able to prescribe sprays to moisten the mouth.
- Avoid traditional mouthwash. Most mouthwash dries out the mouth and destroys the oral microbiome.
- Rinse with a diluted baking soda solution a few times per day. This may provide an additional buffer within the mouth and keep cavities under control.
Can saliva damage teeth? Technically, a lack of saliva can damage teeth.
If you sleep with your mouth open, have a condition such as Sjogren’s syndrome, or take medications that cause dry mouth, you probably have low rate of saliva flow. Particularly at night, slow saliva flow will lead to cavities and potentially other issues like gum disease or sensitive teeth.
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