Digestive System

Cystic fibrosis causes problems with how the digestive system functions


The CFTR* protein is found throughout the body, meaning that people with cystic fibrosis (CF) may experience a wide range of symptoms. These symptoms, and how severe they are, can vary dramatically between people with CF. This variation is the result of each individual’s CFTR mutations, genes, and surroundings.1


The digestive system

The process of digestion, breaking down food to absorb the nutrients, begins in the mouth and continues as the food passes into the stomach and small intestine. Here, the pancreas plays an important role in breaking down and absorbing nutrients.2


The pancreas

The pancreas makes enzymes that the body uses to break down food.

In a person with CF, pancreatic ducts get blocked by mucus. This makes it harder for these enzymes to enter the small intestines where they are needed to do their job.1


Pancreatic ducts can become blocked with mucus

Without these enzymes, the body may have trouble breaking down food and absorbing vital nutrients. This may lead to:1

  • Poor growth, delayed puberty and slow weight gain, even if a lot of food is eaten.
  • Frequent, greasy, and bulky stools or difficult bowel movements.

Over time, mucus blockages can start to damage the cells of the pancreas and reduce enzyme production. This is extremely common in people with CF2,3

Alongside medication such as enzyme tablets, many people with CF are advised to follow a CF-specific diet to provide the nutrients they need and help manage digestive symptoms.


*CFTR = Cystic fibrosis transmembrane conductance regulator


Cystic Fibrosis–Related Diabetes (CFRD)

Around 1/3 of adults with CF have cystic fibrosis–related diabetes (CFRD).1

As people with CF get older, damage to the pancreas can mean it stops producing enough insulin (a hormone that helps the body manage glucose levels in the blood). Without enough insulin the person may develop diabetes.1

Some people with CFRD may find they need to drink and urinate more, feel very tired, lose weight, or have trouble gaining weight. They may also experience a decrease in lung function that cannot be explained. Other people with CFRD, however, may have no symptoms.1,4

If you are concerned about any CF-related symptoms, please ask your doctor or nurse for advice.


Other digestion-related symptoms

People with CF may experience a variety of digestive problems, which may result in:

  • Weight fluctuation – Some people with CF may experience weight loss, or struggle to gain weight for various reasons. These might include reduced flow of pancreatic enzymes to the small intestine making it hard to release the nutrients from food, needing extra energy to fight off infections and, for those with CFRD, not being able to use the sugar from the foods they eat.1
  • Distal intestinal obstruction syndrome (DIOS) – Some people with CF may produce stool that is thicker than usual because of difficulties digesting food. This can block the small intestines causing pain and nausea. DIOS treatment varies based upon the severity of the symptoms and obstruction.4
  • Gastroesophageal reflux disease (GERD) – GERD is very common in people with CF. GERD occurs when stomach acid travels upwards into the oesophagus (the tube that connects the mouth to the stomach). This may cause a heartburn sensation, pain and swelling.5
    1. O'Sullivan B and Freedman S. Cystic fibrosis. Lancet 2009; 373(9678): 1891 ̶ 1904.

    2. Robinson NB and DiMango E. Prevalence of Gastroesophageal Reflux in Cystic Fibrosis and Implications for Lung Disease. Ann Am Thorac Soc 2014; 11(6): 964-968.

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