How Dysphagia Disrupts Food Digestion

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.

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Dysphagia is characterized by difficulty swallowing. Several neurological conditions, such as stroke, dementia, cerebral palsy, Parkinson's disease, and multiple sclerosis can cause dysphagia if the swallowing muscles become weak or lose coordination. People living with dysphagia may experience the following symptoms when trying to swallow:

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

Normal Swallowing and Digestion of Food

The first step in swallowing is the formation of a food bolus. This step can be severely impaired if you have dysphagia.

A food bolus is a small, round mass of food that is formed in the mouth during the early phase of digestion. The formation of a food bolus makes the process of swallowing easier and safer and also helps begin the process of food digestion (breakdown) so that absorption of nutrients can occur in the stomach and small intestine.

A food bolus is formed as food is chewed, lubricated with saliva, mixed with enzymes and formed into a soft cohesive mass. The bolus remains in the oral cavity (mouth) until the process of swallowing begins.

The initial formation of the bolus is dependent upon four steps of oral processing that can be disrupted if you have dysphagia. 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

Once the mouth and throat muscles begin the process of swallowing, the food bolus moves down the esophagus fairly quickly, aided by involuntary (not deliberate) muscular movements of the esophagus. The bolus then passes through a muscle that separates the esophagus from the stomach, called the esophageal sphincter. This muscle closes after the food bolus enters the stomach so that the food remains in the stomach where it is further broken down during the gastric digestion process.

As a bolus enters the stomach, it enters into the curvature of the stomach. During the gastric digestion process, the bolus is chemically processed by the acids and enzymes that are produced in the stomach. Eventually, as the bolus is further broken down, some of the nutrients in the food bolus are absorbed in the stomach. The majority 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 digestion 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, dysphagia can hinder the efficient formation of the food bolus.

A Word From Verywell

If you have experienced dysphagia, your swallowing problems may improve on their own over time. However, there is no guarantee that you will improve without intervention, and it is important to evaluate the cause of the swallowing problem( usually done by a modified barium swallow study). There are several ways that you can gain better swallowing abilities if you have 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 procedures such as neuromuscular electrical stimulation (NMES).
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  • Sasegbon A, Hamdy S. The anatomy and physiology of normal and abnormal swallowing in oropharyngeal dysphagia. Neurogastroenterol Motil. 2017;29(11). doi:10.1111/nmo.13100