CF and Macronutrients

Adequate calories to support normal growth and development are essential, especially in the presence of pancreatic insufficiency. Energy intake should be based on the patterns of weight gain and growth in the person. If an individual has significant growth deficits, lung disease, or malabsorption, energy requirements may be significantly increased. Currently there is no perfect method to estimate the caloric needs of a person with CF. Instead, a steady rate of weight gain in growing individuals should be the goal. For adults, the desired outcome is to maintain an acceptable weight in relation to height with optimal fat and muscle stores.

To obtain adequate calories and compensate for any fat malabsorption, individuals with CF often require a greater fat intake than what is normally recommended for the general population. Fat restriction is not recommended, because fat is an important energy source, and pancreatic enzyme replacement therapy is used to aid its absorption. Medium-chain triglycerides (MCT) require less lipase activity than long-chain fatty acids and may be utilized as a better source of fat calories. MCT have a fatty acid chain length between 6 and 12 carbons, making them short enough to be water soluble. They require less bile salt for solubilization and can be transported as free fatty acids through the portal system. Adequate protein intake is essential to meet the needs of growing individuals and maintain protein stores. Good nutrition also plays an important role in preparing the individual with cystic fibrosis for potential transplant later on in life.

Nutrition management is critical for the health and survival of patients with cystic fibrosis-related diseases. Since a majority of these patients have difficulty maintaining weight, calorie restriction is never appropriate. For patients on insulin, carbohydrate counting offers a great degree of flexibility. Patients should be able to eat as they choose with appropriate insulin coverage. Although carbohydrate is not restricted, patients should be taught to distribute carbohydrate calories throughout the day and to avoid concentrated carbohydrate loads.

CF diagram

Pancreatic Complications in Cystic Fibrosis

The pancreas, located behind the stomach in the center of the abdomen, extends into the left side of the abdomen. It is connected to the first part of the intestine, the duodenum. The pancreas secretes enzymes that aid food digestion and help to regulate blood sugar.

In CF, the altered transport of electrolytes across pancreatic tissues leads to abnormal production of digestive enzymes. Decreased production of sodium bicarbonate makes pancreatic secretions dehydrated and thickened, blocking the pancreatic ducts. Despite these blockages, the pancreas continues to make more enzymes required for food digestion. These abundant enzymes damage the pancreatic tissue, eventually leading to fibrosis of the pancreas until it is no longer able to produce enough enzymes to properly digest food.

Pancreatic insufficiency occurs when the pancreas loses about 90% of its ability to secrete digestive enzymes. Patients become unable to digest food properly, which leads to the malabsorption of nutrients, or even malnutrition. Vitamins, such as A, B12, D, E, and K, and fats, are the most important nutrients that are not absorbed when a patient has pancreatic insufficiency. 

The impaired absorption of fats causes diarrhea, weight loss, and malnutrition, but supplemental pancreatic enzymes can help with digestion of fats and reduce diarrhea. Approximately 80% of CF patients develop pancreatic insufficiency.

The following vitamin deficiencies result from pancreatic insufficiency:

Vitamin A: Visual and Skin Changes

Vitamin B12: Anemia

Vitamin D: BoneAbnormalities

Vitamin E: NeurologicalProblems

Vitamin K: BloodClottingProblems

CK vitamins


Sixty Five Roses

Cystic fibrosis is the most common fatal genetic disorder in North America. The disorder produces thick, sticky mucus secretions that may seriously impair the function of multiple organs in the body. Most notably, these organs are the pancreas and lungs. Just a few decades ago, an infant born with CF seldom survived to adulthood. Today, the outlook is much brighter, with adults reaching their 30’s, 40’s, and some even into their 50’s.

Cystic fibrosis has three major consequences: chronic lung disease, pancreatic insufficiency, and abnormally high electrolyte concentrations in the sweat. Chronic lung disease develops because the airways in the lungs become congested with mucus, causing breathings to be strenuous. As the thick mucus stagnates in the bronchial tubes, bacteria multiply there. Lung infections are the usual cause of death in people with cystic fibrosis.

Cystic fibrosis causes some degree of pancreatic insufficiency in all cases, with about 90% of cases serious enough to require enzyme replacement therapy. With aging, damage to the pancreas deteriorates. The thick mucus obstructs the pancreatic ducts and interferes with the secretion of digestive enzymes, pancreatic juices, and pancreatic hormones. Eventually, the pancreatic cells are surrounded by mucus and are gradually replaced by fibrous tissues. Malabsorption of many nutrients including fat, protein, vitamins, and minerals often leads to malnutrition. Additionally, the secretion of insulin may be affected resulting in glucose intolerance and diabetes.

The therapy of cystic fibrosis aims to promote appropriate growth and development and prevent respiratory failure and complications. Treatment includes respiratory, diet, and drug therapy.

Nutrient losses through malabsorption, frequent infections, rapid turnover rate of protein and essential fatty acids, high protein catabolism, and high basal energy expenditures raise energy needs for people with cystic fibrosis to between 120%-150% of the RDA for gender and age. Extra energy is needed simply to breathe. RDs estimate individual energy requirements based on basal metabolic rate, activity level, pulmonary function, and degree of malabsorption.

Obtaining enough energy can be complicated, but because people with CF frequently experience a loss of appetite that is aggravated by repeated infections, emotional stress, and drug therapy. Coughing to clear the lungs may trigger vomiting or reflux of foods from the stomach. Thus the person with cystic fibrosis finds it difficult to take in enough food energy, protein, and other nutrients to meet needs.

NIH- Cystic Fibrosis

Cystic Fibrosis Foundation