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What Is a Food Bolus?

A food bolus obstruction may cause choking.
A diagram of the digestive system.
The lower esophageal sphincter opens to allow the bolus to pass, and then closes to prevent digestive fluids from entering the mouth.
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  • Written By: Jennifer Voight
  • Edited By: Jacob Harkins
  • Last Modified Date: 09 November 2014
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In digestion, a food bolus is the mass of food formed in the mouth after thorough chewing and mixing with saliva. This mass is called a food bolus during its journey from the mouth down the esophagus. Once the bolus has passed into the stomach it is called chyme.

When food enters the mouth, it must be prepared for swallowing. Teeth masticate, or chew, the food, beginning the chemical and mechanical process of digestion. Enzymes in saliva break down carbohydrate and starches. Once the lingual nerve of the tongue senses that the food is holding together in a softened ball, it moves the bolus through channels formed by the tongue and palate toward the pharynx at the back of the throat.

Once in the pharynx, the bolus touches receptors that tell the epiglottis to close over the trachea while the food bolus passes so food isn’t aspirated into the airways. At the same time, the soft palate rises up to prevent food from moving into the nose. Because of this, chewing, breathing, and talking cease temporarily.

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As the food lump moves from the pharynx into the esophagus, the upper esophageal sphincter opens to allow the bolus to pass, and closes behind it to prevent digestive fluids from entering the mouth. The bolus enters the esophagus, a long, tube-like structure that contracts in rhythmic waves called peristalsis, pushing the bolus toward the stomach. At the end of the esophagus, the lower esophageal sphincter opens, allowing the bolus to enter the stomach and closes behind it to prevent stomach acids and partially digested food from entering the esophagus.

A food bolus obstruction may happen when someone with an underlying condition does not chew food, usually meat, thoroughly, and the food gets stuck in the esophagus. Schatzki rings may cause narrowing in areas of the esophagus, making it difficult for the bolus to pass. Food bolus obstruction can also be caused by peptic stricture, which is a narrowing of the esophagus caused by long-term gastroesophageal reflux disease. Obstructions can be common in the elderly, children, mentally impaired, and those who have suffered a debilitating health problem such as a stroke.

If the obstruction does not resolve on its own, emergency treatment may be necessary. Symptoms of esophageal food bolus obstruction may be pain in the chest, excessive salivation, painful swallowing, or a choking sensation. Endoscopy is frequently the first treatment for an obstruction and can not only remove the obstruction, but diagnose underlying condition that caused it.

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live2shop
Post 7

About a year ago, I started having occasional problems with the upper sphincter muscle at the top of the esophagus. When I would eat dry rice or bread, the sphincter wouldn't open completely to let the bolus go on its way down the esophageal tube.

It was an awful feeling. Drinking water did no good. I just had to wait until it slipped down.

I finally went to the doctor and had a procedure that stretched the upper sphincter. Things are much better now. I just have to take small bites and chew well, in case it tightens up again.

Bertie68
Post 6

After reading the first paragraph of this article, I had to chuckle. Just imagining this blob of food called a bolus making its way from the mouth down to the stomach is a little humorous. But when you think about it, the process is quite an engineering feat from mother nature.

I didn't realize that the first steps in breaking down the chemicals in food began with the chewing process.

I wonder how many people realize that when you start to swallow your food, messages go out to close the breathing tube and part of the throat goes up to keep food from going into your nose?

Since eating and also breathing are essential for survival, evolution figured out ways to keep food from going into breathing areas.

sunnySkys
Post 5

@KaBoom - The idea of the food bolus is a bit entertaining when you think about it. However, a food bolus doesn't really exist for all that long. Like the article said, once it reaches the stomach it's called something else. I don't know that it was really necessary to give this a name!

KaBoom
Post 4

I don't know why, but I find it really entertaining that there is actually a name for a blob of chewed up food. I suppose in order to talk about the workings of the digestive system, you would have to name it. But I am entertained nevertheless!

I also never realized you couldn't breathe and swallow at the same time. Well, I'm sure I did, but I've just never thought about it before. However, it makes sense that you wouldn't be able to breathe while a food bolus is going down your throat. After all, we don't breathe and swallow food down the same "pipe."

umbra21
Post 3

@indigomoth - I've heard that the chewing thing is a myth. It was made up by someone who basically wanted to sell a book and has been told to people ever since as though it was fact.

I know that it sounds like it makes sense, especially now when people seem to eat on the run all the time, but really the bolus is usually chewed as much as it needs to be.

The only thing chewing thoroughly would really do is slow you down enough that you would register the blood sugar rise from food absorption and stop feeling hungry in time to stop you from overeating.

But, you could do that by eating something small before the main meal, or simply slowing down and enjoying each bite, rather than masticating it to death.

indigomoth
Post 2

I've been told that you are supposed to chew the food bolus as much as possible, so that it is nearly liquid by the time it passes through your throat.

Chewing each mouthful at least thirty times is supposed to improve digestion, as the food is already in a good state to be digested.

Food chewing is also supposed to be good for the look of your chin. I know it sounds ridiculous, but I've heard that you can actually reduce a double chin by chewing more, because it tones up the muscles there.

I don't know if it's true though. I always forget to chew as much as you're supposed to.

KoiwiGal
Post 1

After I traveled through a country that had malaria, I was advised to take some medication (I can't remember what it was called) for a few weeks to make sure there was no malaria still in my liver.

Well, I read the instructions wrong. I thought I was supposed to take two pills once a day, when it was one pill twice per day.

Taking both pills at once gave me terrible heart burn and it seemed to injure my esophageal sphincter. I suspect it literally was burned by the acid reflux.

The weird thing was, it actually made it painful to pass the food bolus down there. It was a place I'd never really thought about before, because ordinarily you don't really feel it.

So it was really strange to suddenly have a pain in my chest every time I went to swallow food.

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