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Diet and Nutrition Considerations with Cystic Fibrosis

Good nutrition helps people with cystic fibrosis (CF) control many of the gastrointestinal (GI) problems common to the disease, helps support optimal lung function and improves quality of life.

BMI goals for each stage of life

The desired body mass index (BMI) can vary widely depending on a person’s age and height. For instance, babies and preschoolers with CF should weigh at or above the 50th percentile for their height/length, which may look slightly chubby. A higher height for weight ratio helps a young child grow properly and is linked to better lung function later in life.

Children with CF between ages 2 and 20 should aim for a BMI at or above the 50th percentile for their height.1-3 The CF Foundation recommends that adult women maintain a BMI of at least 22 and adult men should aim for a BMI of at least 23. That’s because research shows that lung function in CF optimizes at those levels.3

The basics of a cystic fibrosis diet

People with CF are also usually encouraged to eat as much as they’d like of high-calorie, high-fat, high-salt foods, along with fruits and vegetables. A diet with 40 percent of total calories from fat is generally recommended. It’s common for someone with CF to need up to twice the daily recommended calories compared to other people.

People with CF also need to pay attention to their liquid intake. A total of 2 to 4 liters of water per day is recommended, with electrolytes added on hot days or when sweating due to exercise.2 More frequent, small, high-calorie meals may be necessary to help a child with CF get enough calories, since the stomach may be slow to empty, causing feelings of fullness.1-3

Supplements for cystic fibrosis

Up to 85% of people with CF have pancreatic insufficiency. This condition is caused when mucus blocks the pancreas from pumping enzymes into the intestines. Without enzymes, food cannot be broken down into nutrients that the body can absorb (malabsorption), leading to malnutrition.

Doctors prescribe pancreatic enzyme replacements (PERT) to help people with CF gather enough energy and nutrition from the foods they eat. Vitamin and mineral supplements may also be prescribed, especially fat-soluble vitamins A, D, E, and K, and the minerals iron and zinc.

Enteral feeding

Some people with CF may need to have an enteral feeding tube (feeding tube or g-tube) inserted if it is hard to eat enough during the day. Enteral nutrition allows for overnight feedings that boost their nutritional intake. Feeding tubes can be expensive, leave scars, or impact self-image, but are generally worth the subsequent improved lung function and increased energy levels.2

Feeding tubes come in two types:

  • A thin tube is inserted through the nose and into the stomach to begin the tube feeding. The main advantage to this type of feeding tube is that it leaves no scars. Disadvantages are that it is more visible, and it is not pleasant to have the tube inserted daily for feedings. There also is a risk that the tube will be inserted into the lungs instead of the stomach, which is associated with poor outcomes.
  • A gastrostomy tube is inserted directly into the stomach and a small “button” is visible on the abdomen. The feeding tube is be connected to the “button” for feeding. The pros of this method are that is more comfortable, easier to use, and safer. The disadvantages are that it requires sedation to be inserted, and the “button may protrude a little under cloths or be visible when wearing swimwear. A g-tube may leave a scar when it is removed.

Tips for boosting calories

A dietitian with a specialty in CF will have tips and ideas that help a family make sure their person with CF gets enough nutritionally-dense calories without developing eating fatigue. Some common suggestions include:

  • Drink whole milk
  • Add nuts and seeds to yogurt and salads
  • Add cheese, avocado and bacon to salads and sandwiches
  • Snack on protein bars washed down with a nutritional supplement drink such as Ensure or Boost
  • Add protein powder to shakes, smoothies and other drinks3

To get the most from these high-calorie boosts, it’s important to remember to carry enzymes at all times and take them before each meal and snack.

Written by: Jessica Johns Pool | Last reviewed: September 2019
  1. Elborn JS. Cystic fibrosis. Lancet 2016; 388:2519-31. http://dx.doi.org/10.1016/S0140-6736(16)00576-6.
  2. Dennett C. MNT in Cystic Fibrosis Care — What RDs Need to Know. Today's Dietitian. April 2017. Vol. 19, No. 4, p. 44.
  3. Cystic Fibrosis Foundation. Nutritional Basics. Available at: https://www.cff.org/Life-With-CF/Daily-Life/Fitness-and-Nutrition/Nutrition/Getting-Your-Nutrients/Nutritional-Basics. Accessed 5/22/2019.