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