Food Bolus

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What is a Food Bolus?

A food bolus is a small, round mass of food that is formed in the mouth during the early phase of digestion.

A food bolus is formed when a piece of food is chewed, lubricated with saliva, mixed with enzymes and formed into a soft, lubricated and cohesive mass. The bolus is held in the mouth, or oral cavity, until the process of swallowing begins.  Once the mouth and throat muscles begin the process of swallowing, the food bolus moves down the esophagus and into the stomach, where it is further broken down during the gastric digestion process.

The initial formation of the bolus is dependent upon four steps of oral processing. These steps include:

  • Moving the food from the front of the mouth to the teeth
  • Transporting the food to the back of the mouth to form a bolus
  • Moving the bolus to the back of the tongue for swallowing
  • Swallowing the bolus

As a bolus enters the stomach, it enters into the curvature of the stomach, forming layers according to the density of the bolus. During the gastric digestion process, the bolus is chemically broken down by the acids and enzymes that are produced in the stomach. Eventually, the bolus is further broken down, and the some of the material is absorbed in  the stomach, while much of the material travels to the small intestine for further breakdown and absorption. 

Bolus formation and disintegration are important steps in the digestion process for several reasons. First of all, the formation of a soft and lubricated food bolus allows food to travel more easily through the different regions within the digestive system.

And, the alteration in the food's texture and composition begins the chemical breakdown process, which is the process by which the food we eat is broken down into particles small enough so that the body can absorb the nutritional components into the bloodstream. These characteristics of food bolus formation ultimately control the rate by which food and nutrients are absorbed and released into the body.

Normally, a food bolus is formed at a steady rate and then travels through the digestive system efficiently for further breakdown and absorption in the stomach and in the small intestine. However, a problem called dysphagia (trouble swallowing) can hinder the efficient formation of the food bolus.

Many people who are living with neurological disease, or who are stroke survivors, experience difficulty swallowing.  People living with dysphagia have difficulty eating, drinking, and taking medicine. If not adequately diagnosed and managed, dysphagia can lead to poor nutrition, aspiration pneumonia and further disability. Dysphagia is not the same as painful swallowing or the feeling of having a lump in the throat.

Symptoms of Dysphagia

People living with dysphagia may experience the following symptoms when trying to swallow:

  • Choking
  • Coughing or gagging
  • Liquid coming out of their nose
  • Food getting caught in the lungs
  • Weakened voice
  • Drooling
  • Lack of tongue control
  • Loss of gag reflex

Management of Dysphagia

The management of dysphagia includes lifestyle adjustments, exercise therapy and medical treatment.

Lifestyle adjustment

Posture changes, both standing and seated, as well as eating slower are simple methods that can ease the process of swallowing. Thinner liquids, like water, are more difficult to swallow if you have dysphagia. Changing the thickness of liquids and eating soft foods can be helpful.

Exercise therapy

Treatment of dysphagia involves therapy with the help of speech, language, occupational or physical therapists. Exercises of the tongue, lips, throat, and mouth will relax and strengthen the muscles that control swallowing and increase flexibility of the area.

Medical therapy

There are prescription medications that can help open the muscles of the throat to make swallowing easier. Other forms of treatment may include neuromuscular electrical stimulation (NMES).

Sources:

Bolus matters: the influence of food oral breakdown on dynamic texture perception, Devezeaux de Lavergne M, van de Velde F, Stieger M, Food Funct. 2016 Sep 16

Edited by Heidi Moawad MD

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