Spit, drool, and more recently, hawk-tuah… all choice words associated with some rather unsavoury situations that involve saliva.
As eek-inducing as this by-product of the mouth appears to be, your oral health would be in a very different state if not for your saliva. And your body knows that – it produces one to two litres a day, and enough to fill a bathtub in a year. In fact, during your lifetime, you could produce over 23,000 litres of saliva, according to Cleveland Clinic.
But what does your spit contain that makes it essential, other than to make swallowing easier? And should you see a doctor if you can’t control your saliva or if your mouth feels as dry as the desert? Here’s a look.
WHAT’S IN SALIVA AND WHAT DOES IT DO?
Saliva is made up of 99 per cent water, with the remaining 1 per cent comprising proteins, electrolytes and other substances, said Dr Ker Liang, an ENT surgeon and the medical director of Aglow ENT Centre.
Generally, your drool consists of two types of saliva: Serous saliva and mucous saliva. Serous saliva is primarily watery and contains enzymes like amylase, which aids in carbohydrate digestion. Mucous saliva is thicker and acts as a lubricant to protect your mouth and prevent tissues from sticking, such as your tongue gumming itself to the roof of your mouth.
It goes without saying that the function of saliva is multi-fold. It is secreted to pre-digest the rice, noodles or other carbohydrates in your mouth as you chew. In fact, without saliva, you wouldn’t be able to taste, according to Cleveland Clinic, as the food molecules must dissolve in saliva before they can be detected by your taste buds.
Other than pre-digesting food as you chew, saliva also “flushes out” the leftover food and drink in your mouth after you’ve swallowed, which can otherwise “erode the teeth and cause cavities or gum disease”, said Dr Ker. “At the same time, it helps to rebalance the pH disrupted by the foods and drinks we consume.”
That’s not all. Saliva’s microbe-limiting enzymes can protect against infection in the mouth, said Dr Ker. Certain substances in your drool can help prevent calcium loss from teeth as well as promote tissue healing (you’d know if you’ve ever accidentally bitten your tongue or the inside of your cheek).
But you might want to rethink pre-chewing your baby’s food or giving a dropped pacifier a quick suck to “clean” it. “There could have been an impression that a parent’s saliva contains non-harmful bacteria that can trigger a positive immune response when transferred to the baby, either by pre-chewing or even sucking on pacifiers to clean them,” said Dr Ker.
“While not wrong, parents who adopt this habit should consider the risk of transmitting bacteria from their mouths to their babies,” she said.
HOW IS SALIVA PRODUCED?
According to Dr Ker, there are numerous salivary glands that are in charge of saliva production. Among them, there are three pairs of major salivary glands:
- Parotid glands: The largest of the salivary glands, they are located in front of your ears. Each parotid gland is slightly smaller than your ear.
- Submandibular glands: These are found below either side of the jaw and together, they are about the size of a walnut.
- Sublingual glands: These almond-sized glands are found below the right and left sides of the tongue.
These glands are stimulated by taste, smell and the act of chewing, she said. “The amount and type of saliva produced can vary, depending on the type of stimulation, and are regulated by the nervous system.”
Even throwing up activates your glands big time, according to Cleveland Clinic, to dilute and neutralise the stomach acid that comes up in your vomit.
Interestingly, how much you salivate can tell you something about your personality. It has to do with a part of your brain called the reticular activating system (RAS), which responds to stimuli like sour food and social contact, according to BBC.
Scientists think that introverts tend to already have a high level of RAS activity even without stimulation. So, when a small stimulus, such as a few drops of lemon juice, is given to introverts, they tend to salivate about 50 per cent more than extroverts, reported BBC. And because the RAS also reacts to social contact, this could mean that introverts react more strongly to meeting people, too. What’s not clear is, would the lemon juice test make a good ice-breaker at parties?
CAN THESE SALIVARY GLANDS GET INFECTED?
Yes, they can. “The parotid gland tends to warrant more attention not only because it is the largest salivary gland, but also because of its prevalence as a tumour site,” cautioned Dr Ker. “Although most salivary gland tumours are benign, they are largely found in the parotid gland.”
Viral infections such as mumps also tend to occur in the parotid gland, said Dr Ker. “When the parotid gland is impacted, it is usually visible through signs of swelling of the upper cheeks, given the location of the glands.”
But hang on, aren’t you already vaccinated against mumps as a baby with the MMR (measles, mumps, rubella) combination vaccines? Can you still develop mumps as an adult? According to Statista, other than babies and preteens from ages zero to 14 years old, the next most prevalent age groups to develop mumps are the 25-34-years-old group, and the 45-54-years-old group.
“Mumps, which is the swelling of the salivary gland, can affect individuals well into adulthood even if they are vaccinated as a baby,” said Dr Ker. “This happens as the immunity provided by the MMR shots decreases over time and individuals are not as well protected long after the shot; hence, when exposed, individuals can still develop painful symptoms like swelling of the jaw, fatigue and fever.”
Opting for an MMR booster is your key preventive measure, she added. Mumps may be treated with medication, while tumours may be surgically removed, she said.
Another infection of the salivary glands is sialadenitis. “This typically occurs due to an inflammation in the salivary gland or connecting ducts that triggers an infection,” said Dr Ker. “It can be caused by a variety of reasons, including the presence of a bacteria or virus, dehydration, other illnesses or poor oral hygiene.”
Signs to look out for include decreased saliva production, dry mouth, swelling of the cheek and pain while eating. “If you suspect any sialadenitis symptoms, visit an ENT specialist, who can provide appropriate treatment ranging from antibiotics, home remedies or in some cases, a surgical approach to remove an abscess or blockage if necessary,” she said.
WHEN DO YOU NEED TO SEE A DOCTOR?
Some instances of drooling could be linked to neurological disorders such as Parkinson’s disease and amyotrophic lateral sclerosis (ALS). “Infections like sinusitis or tonsillitis can also result in drooling symptoms. In those instances, be sure to visit an ENT specialist for a proper examination and treatment,” advised Dr Ker.
She highlighted that it is unusual for saliva to thicken to the point of feeling uncomfortable or difficult to swallow. “If you notice such symptoms or that your saliva starts to clump or stick to your gum, you may want to consult a doctor for a proper diagnosis.”
Often, your saliva’s viscous consistency is caused by not drinking enough water. “Sometimes, sick individuals may find their saliva thickening as it mixes with mucus during a flu or cold,” said Dr Ker.
HOW CAN YOU KEEP YOUR SALIVARY GLANDS HEALTHY?
One word: pH. The normal pH range for saliva is 6.2 to 7.6, with 6.7 being the average.
“Maintaining the pH balance of your saliva is important because it helps inhibit the growth of harmful bacteria in the mouth,” said Dr Ker. “A stable, healthy pH level in the mouth reduces the risk of oral diseases, including various types of infections.” And that’s not mentioning the good it does for your teeth by preventing the enamel from being eroded by acidic foods and drinks, she added.
In fact, your saliva’s pH can say a lot about your oral health. In a study on 300 subjects, those with chronic gingivitis were found to have more alkaline saliva, whereas those with chronic periodontitis had a more acidic pH.
