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.

Diet plays an important role in managing cystic fibrosis to 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 sample cystic fibrosis diet menu.

Causes and risk factors

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, damage, and inflammation of the lungs and other organs.

The most commonly affected organs include the:

  • lungs
  • pancreas
  • intestines
  • liver

In the United States, cystic fibrosis occurs in 1 in 2,500 to 3,500 white newborns annually (2).

The condition is less common in other ethnic groups, affecting 1 in 17,000 Blacks and 1 in 31,00 Asian Americans annually.

Symptoms

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 (3).

Diagnosis and treatment

Most people are diagnosed with cystic fibrosis through newborn screening and before age one (4, 5).

However, many people are diagnosed as adults.

Your doctor may diagnose cystic fibrosis based on your symptoms and results from certain tests.

These tests can include (5):

  • genetic testing to detect mutated CTFR genes
  • enzyme tests to determine how well your pancreas is working
  • sweat test to measure the amount of chloride, a component of salt
  • a spirometry test to measure your lung function

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

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 (6).

This prevents the enzymes from being released to the digestive tract, where they help breakdown 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 lose weight and 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 to help fight frequent infections (7).

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 sugars levels is especially important with cystic fibrosis as the condition leads to diabetes in 20% of children and 40–50% of adults (8).

Limiting your intake of refined carbohydrates can help reduce the need for medications like insulin to control blood sugar and improve lung function (8, 9).

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 (10).

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

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 the fat-soluble vitamins include (11, 12, 13, 14):

  • 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 (15).

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 (16).

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, and 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 purchase protein powder to add to smoothies.

One-day sample cystic fibrosis diet menu

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

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

Breakfast: Peanut butter toast, an orange, and three whole eggs.

Snack: Full-fat Greek yogurt with almonds.

Lunch: A beef taco burrito bowl containing ground beef, brown rice, shredded cheese and lettuce, diced tomato, avocado slices, and salsa.

Snack: A smoothie made with strawberries, a banana, whole milk, vanilla protein powder, and chia seeds.

Dinner: Grilled salmon with a baked sweet potato and sautéed mushrooms.

Pancreatic enzymes and multivitamins

Most people with cystic fibrosis need to take medically-prescribed pancreatic enzymes before every meal and snack so their bodies can break down food and absorb the nutrients (17).

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 relief from uncomfortable malabsorption symptoms, including nausea, bloating, and diarrhea.

Even with pancreatic enzymes, however, vitamin malabsorption can still occur and lead to deficiencies (18).

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

Your healthcare provider should check your fat-soluble vitamin levels at least annually (7).

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.

Most people with cystic fibrosis need to take pancreatic enzymes with meals along with a daily multivitamin to avoid nutritional deficiencies, maintain a healthy weight, and support immune health.