Nutrition Considerations With Cystic Fibrosis

People with cystic fibrosis commonly have problems digesting food and absorbing nutrients. This can lead to malnutrition and problems with growth in children. They have higher calorie needs than people without the condition.

Cystic fibrosis (CF) is a genetic condition that affects the body’s tissues and glands that produce mucus and sweat. In cystic fibrosis, the body produces thicker and stickier mucus than it should. This thick mucus can build up in the organs and cause blockages, infections, and scarring in the affected organs.

More than 30,000 people in the U.S. live with cystic fibrosis. The disease is most often diagnosed before birth or within the first few days of life. For a child to develop cystic fibrosis both parents need to be carriers of the mutated gene that causes CF.

Symptoms of cystic fibrosis vary depending on which organs are affected. While some people with cystic fibrosis have few to no symptoms, others may experience severe or life-threatening complications. The most common complication of cystic fibrosis is lung issues that cause difficulty breathing.

In this article, you will learn more about the connection between cystic fibrosis and malnutrition, signs and symptoms of malnutrition, and available treatments.

Person holding egg. People with cystic fibrosis have higher protein and calorie needs.

Jackyenjoyphotography / Getty Images

Cystic Fibrosis and Malnutrition

Malnutrition is one of the main problems that arise in cystic fibrosis. Malnutrition in people with CF is the result of a variety of factors.

These include:

  • Issues with the pancreas (an organ that produces digestive enzymes and hormones that regulate blood sugar) that make it hard to break down nutrients in food
  • Burning more energy (having greater metabolic demands)
  • Higher amounts of inflammation
  • A decrease in appetite especially during times of worsened illness
  • Other issues within the digestive system

These and other issues within the digestive system combine to lead to malabsorption, or the inability to absorb nutrients from food.

Receiving proper nutrition is important for living a healthy life and is equally if not more important when living with CF.

Signs and Symptoms of Malnutrition

People with CF and lung involvement may have a reduced appetite, which can lead to malnutrition. However, even with the regular consumption of food, people with CF can still experience signs and symptoms of malnutrition. These include but aren’t limited to:

  • Weight loss
  • Low body mass index
  • Muscle loss
  • Swelling, especially in the feet
  • Stunted growth
  • Low blood sugar, which can cause lightheadedness, nausea, and sweating

Related Gastrointestinal Complications

Malnutrition can also cause gastrointestinal complications. These include:

  • Meconium ilius: A bowel obstruction that occurs in newborns when their first stool blocks the small intestine
  • Constipation: Having few bowel movements or difficulty having them
  • Distal intestinal obstructive syndrome (DIOS): An obstruction that occurs when the small intestines are blocked by thickened stool caused by poor absorption of nutrients
  • Gastroesophageal reflux disease (GERD): Occurs when the stomach contents rise back up toward the throat, causing symptoms like acid reflux, vomiting, and pain
  • Small intestine bacterial overgrowth (SIBO): Caused by excess bacteria in the intestine that can lead to diarrhea, gas, bloating, and poorer absorption of nutrients

Body Mass Index Goals

Body mass index (BMI) is an easily calculated measurement that can give a quick overview of health. This calculation is based on height and weight. It correlates with fat mass and lean body mass, although it is not a direct measurement of body composition.

People who have a lower BMI often weigh less than is ideal for their height, and those with a higher BMI weigh more than is ideal for their height.

BMI is a dated, flawed measure. It does not take into account factors such as body composition, ethnicity, sex, race, and age.
Even though it is a biased measure, BMI is still widely used in the medical community because it’s an inexpensive and quick way to analyze a person’s potential health status and outcomes.

BMI is important in people with CF because a low number can indicate malnutrition and is also associated with poorer health with CF. Higher numbers, which can indicate more fat mass, have also been shown to affect the lungs’ ability to function.

The Cystic Fibrosis Foundation recommends a BMI of at least 22 for women and 23 for men. For people under the age of 21, the recommendation is to be at or above the 50th percentile on the Centers for Disease Control and Prevention (CDC) growth chart.

While other factors need to be considered, such as true body fat percentage, aiming for a BMI in the normal range for your age and height is a step in the right direction to living well with CF.

Treatment for Malnutrition

The goal of treatment for malnutrition is to make sure that people with CF can get enough nutrients to sustain them. There are several treatment options for malnutrition.

Pancreatic Enzyme Replacements

In people with CF, the pancreas does not function the way it should. This makes it difficult for the body to digest and absorb food. Normally the pancreas produces enzymes that break down food.

Pancreatic enzyme replacements are pills that can be taken orally, or supplied through a feeding tube, to aid the pancreas in digestion.

Nutritional Supplements

Nutritional supplements are specifically formulated liquids or powders that are mixed with water. They can be consumed as a drink or provided through a feeding tube.

These supplements provide extra calories, vitamins, and minerals in a compact formula. Often, they are formulated to provide higher levels of protein and calories than you might get from a typical meal.

Nutritional supplements can help people with malnutrition receive the nutrients they need and maintain a healthy BMI.

Enteral Feeding

Enteral feeding allows people with CF to “eat” without having to consume food. With enteral feeding, a tube is placed either through the nose and leads directly to the stomach, or the tube is placed directly through the skin of the abdomen into the stomach.

With the tube, nutrients, supplements, and high-calorie liquids can be administered directly into the stomach, bypassing much of the digestive tract. Enteral nutrition is only considered as a treatment option after oral dietary and supplemental intake has failed to meet nutritional needs.

Enteral feeding is a highly effective, though sometimes cumbersome, way to ensure that a person with CF receives the nutrients they need.

Cystic Fibrosis and Nutrient Intake

Nutrient intake is important for people with CF since malnutrition is often associated with the disease. The general recommendation is to consume a higher-calorie diet that focuses on fat and protein. Supplementation can also be helpful.

Getting Enough Calories

People with CF typically need 1.5 to two times the number of calories a person of the same height and weight without CF needs. If you are underweight, your healthcare provider may recommend you gain weight.

To gain weight, you typically need about 500 extra calories a day. This can be added to your diet in a variety of ways.

You can add an extra snack, such as a turkey sandwich with avocado, or you can add 100 calories to each meal by consuming a high-calorie snack with it, such as grabbing a handful of nuts to go with your dinner.

Meeting Protein Needs

Protein is an important part of any diet as it helps the body build muscle. Since low muscle mass is associated with a decline in lung function, consuming adequate protein is important for people living with CF.

The typical dietary recommendation is that 20% of calories should come from protein. However, one study argued that a person with CF likely has higher protein needs to support their body’s processes and should consume more than the current recommendation.

Vitamins and Minerals

Vitamins and minerals are a vital part of any diet. People with CF tend to be deficient in several vitamins and minerals and may need to supplement them. Commonly, people with CF are deficient in vitamins A, D, E, and K.

One study found that those who were dealing with an exacerbation of lung complications were low in copper, iron, and calcium.


Malnutrition is a common concern in cystic fibrosis. People with the condition often require more calories, and their bodies do not digest or absorb food the way they should.

Maintaining a healthy BMI is important for people to live well with cystic fibrosis. Treatments for malnutrition include pancreatic enzyme replacement therapy, nutritional supplements, and enteral feeding.

A Word From Verywell

Taking care of your nutritional needs is an important part of living well with cystic fibrosis. Talking to your healthcare provider about concerns and questions can help give you direction.

Living with cystic fibrosis, like living with any chronic illness, can require extra effort. Feeling overwhelmed is natural. Finding others who are living with the disease might help you feel less alone.

Frequently Asked Questions

  • How does cystic fibrosis affect the digestive system?

    The thick mucus that occurs in CF can make absorbing nutrients difficult. In CF, the pancreas (which aids in digestion) can be affected.

  • Why do cystic fibrosis patients have a hard time gaining weight?

    Cystic fibrosis patients can require up to two times the number of calories a person without the disease needs. Often, they are unable to meet these requirements due to a variety of factors including loss of appetite and poor digestion and absorption of food. 

  • What are the primary goals of cystic fibrosis treatment?

    Treatment goals for CF are to treat symptoms and infections and maintain proper nutrition and BMI. Although no cure exists, newer treatments are being developed to address the cause of CF.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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