Why Does Food Make My Mouth Water?

10 min read  |  September 12, 2023  | 
Disponible en Español |

Isn’t it amazing how efficiently a healthy body does so many varied jobs, including taking care of digestion? Think about it – for your salivary glands to get your digestive juices flowing, you don’t even need to see that glistening slice of watermelon or a golden grilled cheese sandwich. Just thinking about food will get your juices flowing.

“Our salivary glands produce between one-half and one-and-a-half liters of saliva every day – roughly 1 to 1-1/2 quarts. It’s essential for starting the digestive process within your mouth and for lubricating food for swallowing. Saliva plays other important roles in the body, too,” says Christine D’Aguillo, M.D., an ear, nose and throat specialist with the University of Miami Health System.

Digestion begins with saliva.

Saliva moistens food, making it easy to swallow. It contains enzymes that change the food chemically, starting the digestive process. Then, the stomach and the small intestine complete most of the work of chemical digestion.

 Saliva contains an enzyme that breaks starchy foods down into sugars, which the body can use for energy. This enzyme is called salivary amylase, and it’s similar to the amylase produced by the pancreas.

 “You can do an experiment yourself. If you chew a plain, unsweetened cracker slowly, you should notice it starting to taste sweet. That’s because of the action of digestive enzymes in saliva,” says Dr. D’Aguillo.

 Another enzyme in saliva is called lingual lipase. Research suggests that it plays a role in starting the digestion of fats.

 Where does saliva come from?

Three pairs of glands near your mouth are the main producers of saliva. “The parotid glands sit in your cheeks, on either side of your mouth, in front of your ears. The submandibular glands are underneath the floor of the mouth, in your neck. The sublingual glands are under your tongue,” says Dr. D’Aguillo.

Hundreds of smaller salivary glands are dispersed in and around your mouth. 

“These tiny salivary glands sit underneath the oral mucosa, the moist tissues lining our lips and mouths. Together, the salivary glands keep the oral cavity well lubricated,” she says.

The salivary glands consist of several types of cells. These cell types include acinar cells, which produce saliva. Myoepithelial (my-oh-eppuh-theel-ee-ahl) cells then move the saliva into ducts that empty into the oral cavity.

 Your brain gets things going.

 When you see or even think about food, your nervous system generates signals which arise in your brainstem. The brainstem is located at the bottom of your brain, right above the top of the spinal cord.

 “This area of the brain is sometimes called the ‘old brain’ because, in evolutionary terms, it’s the oldest region of the brain. It controls your body’s most basic functions. These include your breathing, heartbeat, feeding, and digestion,” Dr. D’Aguillo says.

As it receives signals about food, the brain releases special chemicals that tell the salivary glands to make more saliva.

 “The salivary glands produce saliva at all times. But if you eat or smell something good or if something else triggers them, your autonomic nervous system will trigger them to increase the production and change the electrolyte concentration of the saliva they produce,” she explains.

 You don’t necessarily have to be looking at actual food or inhaling its aromas for production to ramp up. Pictures of food or even just thoughts of food can prompt increased saliva flow.

The products of the various salivary glands flow into the mouth, where they combine. 

The main components of saliva include water, mucous, mineral salts, and digestive enzymes.

 In the mouth, the salivary glands’ fluids also mix with elements coming from various sources.

These sources include whole or destroyed cells of the oral mucous membranes (the slick lining of your mouth) and the hundreds of microorganisms living in the mouth.

These microorganisms make up the oral microbiome, which can include a wide variety of different kinds of bacteria, fungi, and viruses. Many members of the microbiome are beneficial, though not all of them are. The “community” in the oral microbiome is the second largest in the body after the one in your gut.

When the products of these different sources combine, a fluid that scientists call “mixed saliva” or “whole saliva” is produced. Most of us just think of this fluid as saliva.

 Saliva plays a role in your immune defenses.

Special cells in the salivary glands, and to a lesser extent in the lining of the mouth, produce substances called immunoglobulins or antibodies. Their job is to identify and attack potentially harmful foreign objects that have entered the mouth, such as viruses.

Everyone experiences the sensation of their mouth being dry now and then. It often occurs in people who are somewhat dehydrated or feeling anxious. But some people suffer from dry mouth often.

People have compared living with a mouth that lacks enough saliva to driving a car without enough oil to grease the engine.

What are the symptoms of dry mouth?

  • Your mouth and/or tongue feeling dry and sticky
  • Sore throat and hoarseness
  • Bad breath and dental problems
  • Saliva that seems stringy or thick
  • Changes to your ability to taste food
  • Problems with dentures, such as looseness, soreness and infections
  • Lipstick sticking to the teeth

“If dry mouth persists, it’s best to see your dentist or doctor. There are a lot of reasons for the problem, which is also called xerostomia. And there are steps you can take and treatments that can help,” said Dr. D’Aguillo. 

What causes dry mouth?

Many things can lead to dry mouth, also known as xerostomia (zeer-oh-STOW-me-uh). Simply not drinking enough fluid is one possible cause. Age-related changes can cause less saliva production.

Hormonal changes, like a drop in estrogen due to menopause, may also reduce salivary production.

 “In one person, dry mouth can have multiple overlapping causes, and we can’t always find an exact explanation,” says Dr. D’Aguillo.

 Medicines are a common culprit of dry mouth.

 “Dry mouth is often a side effect of different medications that we use for a wide range of medical issues, “Dr. D’Aguillo says. 

Here’s a partial list of the drugs that can reduce saliva production:

  • Drugs for anxiety and depression and certain pain medicines
  • Anticholinergic drugs which are prescribed for many different conditions. These include overactive bladder and chronic obstructive pulmonary disorder (COPD). 
  • Certain high blood pressure treatments
  • Some chemotherapy drugs that are used to treat cancer
  • Medicines for Parkinson’s disease

Radiation therapy can also cause a lack of spit.

 About 41% of adults in the U.S. will be diagnosed with cancer of any site at some point during their lifetime, according to the National Cancer Institute. And roughly half of all cancer patients undergo radiation treatments at some point during their treatment.

Such treatments can cause dry mouth. 

“A history of radiation therapy due to cancer, especially to the head and neck, can damage the salivary glands almost permanently,” Dr. D’Aguillo says.

Certain illnesses may attack the salivary glands.

“Sometimes the salivary glands develop conditions that mean they don’t function well, and this can make it hard for you to swallow or taste,” Dr. D’Aguillo explains.

Some autoimmune disorders (ones that arise when the body’s immune system attacks healthy tissue by mistake) can cause the problem. These include Sjogren’s syndrome, which mostly affects those ages 40 or older, usually women. It causes both dry mouth and dry eyes.

Rheumatoid arthritis is another autoimmune disease that can cause dry mouth. Although children and young adults can develop rheumatoid arthritis, it is usually first diagnosed in people between the ages of 30 and 60.

Tips to keep up a good supply of saliva

 Take these steps; make them habits:

  • No matter what else you drink, drink plenty of water.
  • Moderate your consumption of coffee, tea, soda, or energy drinks. Also, drink plenty of water.

 Sometimes, you may hear that caffeinated drinks are dehydrating. The research is unclear. Drinking water along with caffeinated beverages is always best.

Among fruits, watermelon, cantaloupe, peaches, strawberries, oranges and grapefruits are all exceptionally high in water content. So are certain veggies — like lettuce, tomatoes, cucumbers, cauliflower, and zucchini. 

Certain dairy foods, such as plain yogurt, cottage cheese and skim milk, also contain plenty of water.

 If you are experiencing dry mouth, consuming tart candies (such as lemon candies) or sugar-free gum with xylitol can help stimulate saliva production. Such substances, which increase saliva production, are called sialagogues.

Massaging your salivary glands can also help increase the flow of saliva.

Why is my pee yellow?

Don’t count on thirst alone to tell you when to drink.

“You can easily see if you’re drinking enough fluids by looking at the color of your urine,” explains Dr. D’Aguillo. “If it’s a pale yellow, you’re drinking enough fluids. But if it is a deep gold or amber, you probably need to drink more water.”

Dehydration can lead to salivary stones.

“If you get dehydrated and aren’t urinating enough, you can not only get kidney stones, you can also get salivary stones,” Dr. D’Aguillo says.

Usually, salivary stones develop in the submandibular glands in the neck. However, they can grow in other salivary glands.

Stones can cause blockage of the saliva traveling from the gland to the opening of the duct in your mouth. This can cause pain, swelling, and even infection of the affected salivary gland. If you are concerned that you may have a salivary stone, you should see an otolaryngologist right away.

 How are salivary stones treated?

“Usually, non-surgical treatments like applying heat and massaging the area of the gland are enough to treat the stones. If the gland is infected, we may have to prescribe antibiotics and steroids. Sometimes, we do have to do surgery to remove them,” Dr. D’Aguillo says.

Some surgical techniques to remove salivary stones are less invasive than others.

 In a sialendoscopy, the doctor guides a long, slender device that has a camera and a grasping tool at its end through the salivary ducts. This device, called a sialoendoscope, allows the surgeon to locate and remove the stone.

This endoscopic approach works for most small and sometimes medium-sized stones. “Sometimes, when the stones get too large, we have to remove the gland,” Dr. D’Aguillo says.

When our salivary glands are working well, we don’t generally give saliva a thought. 

We may lick our lips when they feel dry or lick a finger to turn a book’s pages. Meanwhile, saliva really is something special.

It constantly softens and smoothes the oral cavity, a uniquely complex place in the body. Only in the mouth do soft tissues (the tongue, palate and cheeks) and hard ones (teeth) engage with the outside world, which enters the oral cavity as food, dust, and microorganisms.

Saliva allows us to enjoy our food and relish a kiss. So, keep drinking your water to care for your salivary glands. They do so much for you.

Milly Dawson is a contributing writer for UHealth’s news service.

Tags: Dr. Christine D'Aguillo, glands that produce, saliva or spit, salivary flow

Continue Reading