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Updated September 4, 2022

Cystic fibrosis is an inherited disease that affects the lungs, pancreas, and other organs.

The condition causes you to produce thick, sticky mucus that can build up and lead to blockages, damage, or infections of these organs.

Making dietary changes with cystic fibrosis can help you avoid nutritional deficiencies, maintain a healthy weight, and support immune health.

This article explains what to eat and avoid with cystic fibrosis and provides a 3-day sample cystic fibrosis diet menu.

cystic fibrosis diet

What is cystic fibrosis?

Cystic fibrosis is caused by a mutation or alteration in the cystic fibrosis transmembrane conductance regulator (CFTR) gene (1).

This mutation causes your cells — which normally produce thin and smooth fluids — to produce thick, sticky mucus that leads to blockages, inflammation, and damage to the lungs and other organs.

The most commonly affected organs include the:

  • lungs
  • pancreas
  • intestines
  • liver

Most people are diagnosed with cystic fibrosis through newborn screening and before age one, but many people are also diagnosed as adults (2, 3).

The symptoms of cystic fibrosis can vary depending on the person, the severity of the condition, and which organs are affected.

Some people may have serious problems from birth, whereas others may not experience symptoms until they are teens or young adults.

Symptoms of cystic fibrosis can include (1):

  • salty-tasting skin
  • persistent cough, at times with phlegm
  • frequent lung infections like pneumonia or bronchitis
  • difficulty breathing
  • weight loss or difficulty maintaining body weight
  • greasy, bulky stools
  • acid reflux

About 98% of men with cystic fibrosis are also infertile due to a blockage or absence of the sperm canal (4).

The treatment for cystic fibrosis depends on its severity and the organs affected but should include diet and supplements as a component.

SUMMARY: Cystic fibrosis is a genetic disorder that causes your cells to produce thick, sticky mucus that leads to blockages, inflammation, and damage to the lungs and other organs.

Cystic fibrosis diet

A cystic fibrosis diet helps prevent nutritional deficiencies and unintended weight loss that can result from pancreatic insufficiency.

Pancreatic insufficiency occurs when the pancreas fails to produce or transport enough digestive enzymes to break down the food you eat.

Pancreatic insufficiency affects up to 87% of people with cystic fibrosis and develops when the ducts that transport digestive enzymes out of the pancreas become blocked with mucus (5).

This prevents the enzymes from being released to the digestive tract, where they help break down proteins, fats, and carbs into their smaller components so they can be absorbed.

Consequently, you can develop malabsorption, which occurs when you can’t absorb enough nutrients from the food you eat.

As a result of malabsorption, you can become deficient in numerous vitamins and minerals and experience weight loss — even if you’re consuming plenty of food.

The most common malabsorption symptoms include diarrhea, nausea, bloating, gas, and passing foul-smelling, greasy, or fatty stools.

People with cystic fibrosis also require more calories and nutrients due to chronic inflammation and frequent infections (6).

SUMMARY: The goal of a cystic fibrosis diet is to prevent nutritional deficiencies and unintended weight loss that can result from malabsorption, chronic inflammation, and frequent infections.

Foods to avoid

Children and adults with cystic fibrosis should avoid or limit refined carbs and foods that can promote inflammation like fried foods.

Refined carbs

Consuming refined carbohydrates in excess makes it difficult to maintain healthy blood sugar levels.

Maintaining healthy blood sugar levels is especially important with cystic fibrosis as the condition leads to diabetes in 20% of children and 40–50% of adults (7).

Limiting your intake of refined carbohydrates can help reduce the need for medications like insulin to control blood sugar as well as improve lung function (7, 8).

Refined carbs include:

  • soda
  • some fruit juices
  • sports drinks
  • specialty coffee drinks
  • cakes
  • cookies
  • candy
  • condiments, such as ketchup or BBQ sauce
  • certain breakfast cereals

Fried foods

Fried foods are pro-inflammatory, meaning they produce inflammation in your body (9).

Eating fried foods can increase the inflammation in your body that is already present from cystic fibrosis, potentially worsening your symptoms and ability to fight infections.

Fried foods to limit or avoid include:

  • fried chicken
  • fish and chips
  • mozzarella sticks
  • onion rings
  • doughnuts
  • churros
  • french fries

SUMMARY: Avoid or limit refined carbs and fried foods to reduce your risk of developing diabetes, improve lung function, and reduce inflammation.

Foods to eat

Children and adults with cystic fibrosis should eat foods that are good sources of fat-soluble vitamins, healthy fats, and protein.

Good sources of the fat-soluble vitamins

The malabsorption that occurs with cystic fibrosis can cause several vitamin deficiencies, especially fat-soluble vitamins.

Fat-soluble vitamins dissolve in fat and include vitamins A, D, E, and K.

The best sources of fat-soluble vitamins include (10, 11, 12, 13):

  • Vitamin A: sweet potato, spinach, carrots, cheese, fortified milk, cantaloupe, peppers
  • Vitamin D: cod liver oil, trout, salmon, UV-exposed mushrooms, fortified milk, eggs
  • Vitamin E: sunflower seeds, almonds, hazelnuts, peanut butter, spinach
  • Vitamin K: natto, collards, spinach, kale, broccoli, soybeans, pumpkin, pomegranate juice, okra, blueberries, lettuce

Healthy sources of fat

Fat contains nine calories per gram — more than double that of carbs or protein.

For this reason, eating plenty of fats can help you meet your calorie needs easier (14).

Healthy sources of fat include:

  • flaxseed
  • chia seeds
  • extra virgin olive oil
  • whole eggs
  • avocados
  • nuts, like almonds and walnuts
  • fatty fish, like salmon, tuna, and herring

Protein

Protein has several important bodily functions, including maintaining and supporting muscle tissue, making enzymes and hormones, and transporting nutrients.

It also plays a critical role in supporting your body’s immune function to fend off infections that frequently occur with cystic fibrosis (15).

Good sources of protein include:

  • Dairy: milk, cottage cheese, yogurt
  • Meats: beef, lamb, veal, pork
  • Poultry: chicken, turkey, duck, eggs
  • Seafood: fish, prawns, crab, oysters, scallops
  • Legumes: kidney beans, navy beans, pinto beans, black beans, lima beans, garbanzo beans, green peas

In addition to these foods, ready-to-drink protein supplements offer a convenient way to help you meet your protein needs.

You can also add protein powder to smoothies.

SUMMARY: Emphasize foods that are rich in fat-soluble vitamins, healthy sources of fat, and protein to reduce your risk of developing nutrient deficiencies, boost your calorie intake, and support your immune system.

3-day sample cystic fibrosis diet menu

Here is a 3-day sample cystic fibrosis diet menu that includes good sources of vitamins and minerals, healthy fats, and plenty of calories from fat:

Day 1

  • Breakfast: scrambled eggs, peanut butter toast, and a banana
  • Snack: full-fat Greek yogurt with almonds
  • Lunch: beef taco burrito bowl
  • Snack: high-calorie protein smoothie
  • Dinner: grilled salmon, baked sweet potato, and sautéed mushrooms

Day 2 (vegan)

  • Breakfast: tofu scramble and peanut butter toast
  • Snack: vegan overnight oats
  • Lunch: vegan burrito bowl
  • Snack: apple slices and almonds
  • Dinner: black bean soup and pita bread

Day 3

  • Breakfast: high-calorie oatmeal made with peanut butter and frozen fruit
  • Snack: Greek yogurt and apple slices
  • Lunch: bacon, tomato, and avocado sandwich
  • Snack: cottage cheese on toast
  • Dinner: sirloin steak, baked potato, and sauteed carrots

SUMMARY: With adjustments to the portion sizes, the foods and snacks in this sample diet can work for adults and children.

Pancreatic enzymes and multivitamins

You may need to take prescription pancreatic enzymes before every meal and snack to break down food and absorb the nutrients (16).

By enhancing the absorption of nutrients, taking pancreatic enzymes can also help you reach and maintain a healthy body weight.

Because pancreatic enzymes improve nutrient absorption, they can provide you with relief from uncomfortable malabsorption symptoms, including nausea, bloating, and diarrhea.

Even with pancreatic enzymes, however, vitamin malabsorption can still occur and lead to deficiencies (17).

As such, taking a multivitamin supplement that contains at least the fat-soluble vitamins A, D, E, and K, like this one, can help you maintain adequate vitamin levels.

Your healthcare provider should check your fat-soluble vitamin levels at least annually (6).

SUMMARY: Taking pancreatic enzymes can improve digestion and provide you with relief from uncomfortable malabsorption symptoms. Additionally, supplementing with the fat-soluble vitamins — A, D, E, and K — can ensure that you maintain adequate levels.

The bottom line

Cystic fibrosis is an inherited disease that causes produces thick, sticky mucus that causes problems with your lungs, pancreas, and other organs.

With cystic fibrosis, you should eat foods rich in fat-soluble vitamins, healthy fats, and protein, and avoid refined carbs and fried foods.

You may need to take pancreatic enzymes with meals along with a daily multivitamin to avoid nutritional deficiencies, maintain a healthy weight, and support immune health.


Gavin Van De Walle, MS, RD, LN
Gavin Van De Walle, MS, RD, LN

Gavin Van De Walle holds a master's degree in human nutrition and bioenergetics. He is a registered dietitian who aims to arm the public with evidence-based nutrition recommendations so they can make their own educated and informed health decisions.