Cystic fibrosis can interfere with good nutrition in two major ways:

1) It increases the body's requirements for nutrients used in energy production, growth, and maintenance.

2) It makes it more difficult for the body to obtain these nutrients from food.

This doesn't mean that CF has to lead to poor nutrition. It simply means that proper nutritional management is a very important part of treatment if the CF person is to achieve optimal growth and development, and maintain the highest possible level of health. Because CF differs so widely from person to person, proper nutritional management will vary widely, too.

Digestion and absorption of nutrients.

Cystic fibrosis affects the pancreas, a specialized gland in the abdomen. One of the pancreas' major functions is producing the chemical substances known as digestive enzymes.

Digestive enzymes are normally delivered to the small intestine in response to food coming from the stomach. In the intestine, the pancreatic enzymes partially digest food; that is, they break large nutrients - proteins, carbohydrates, and fats - into smaller particles. These particles are small enough to pass through the intestinal wall and into the body, in a process called absorption.

In most CF people, CF causes production of a thick mucus that plugs the duct leading from the pancreas to the small intestine. Consequently, not enough enzymes are present to properly digest food. If left untreated, one result is malabsorption, an inability to properly absorb nutrients. The other result is passage of these unabsorbed nutrients in the feces, leading to cramps, gas, and large, foul-smelling stools.

Enzyme replacement therapy.

To compensate for this enzyme shortage, the majority of people with CF must take replacement pancreatic enzymes. These enzymes must be taken to help digest every meal and snack, except for snacks that are virtually free of protein, starch, and fat (such as apple juice). Your nutritionist or physician can tell you more about foods that do not require enzymes.

Studies show that enzyme preparations are equally effective when taken anywhere from a half-hour before to a half-hour after eating. That way, the enzymes are in the small intestine when needed.

The amount of enzyme required varies greatly among CF people, and depends largely on caloric and fat intake. For example, the amount of enzyme required to cover a high-calorie, high-fat meal will be greater than the amount required for a small snack. Another factor that affects dosage is the type of enzyme preparation. Because acid in the stomach destroys some of the enzymes taken in powdered and tablet form, a higher dosage may be required than for encapsulated enzymes, which have a special protective (enteric) coating that dissolves only in the intestine. The correct enzyme dosage can be determined by a physician using a fecal-fat study (which compares fat intake to fat loss in the stools).

Glucose Intolerance.

In CF, fibrosis of the pancreas can gradually lead to impaired function of specialized pancreatic cells, the islet cells. These cells produce insulin responsible for regulation of blood glucose (blood sugar) levels. As a result, some people with CF may become glucose intolerant, that is, less able to clear glucose from the bloodstream.

Management of glucose intolerance usually includes dietary modification in order to regulate the types of food eaten and the timing of food intake. In addition, insulin may be given to lower blood sugar. Your physician can give you more detailed information on this topic.

Caloric Requirements.

One of the major functions of food is to supply energy. The amount of energy a food provides is measured in calories, sometimes abbreviated as cals.

Most people with CF have a higher caloric requirement than other individuals of the same age and sex for these reasons:

• More energy is used in breathing.
• Extra energy is used in fighting infections and during fevers.
• Fewer of the energy-producing nutrients in food are properly digested and absorbed into the body, even when treatment is optimal.

In order to meet his or her energy requirements, the typical CF child receiving enzyme therapy must consume approximately 120 to 150 percent of calories for a healthy child of the same age and sex. This figure varies considerably from person to person, and can be as high as 200 percent of a healthy child. Energy requirements are particularly high for children who are catching up on growth and development after a period of poor nutrition.

How can an individual's calorie requirements be calculated? Your child's nutritionist can do tests to establish the resting metabolic rate (the amount of energy required at rest); with that, total energy requirements can be calculated. On a more practical level, adequate caloric intake can be defined as the level that promotes normal growth and development in children, and maintenance of desirable body weight in grown individuals.

Protein Requirements.

Protein is one of the three energy-producing types of nutrients in food. The other two are carbohydrates (made up of starches and sugars) and fats. In addition to being used for energy production, protein is necessary for growth and maintenance of body tissues, proper functioning of the immune system, and a number of other critical functions.

Most people with CF have higher-than-usual protein requirements. People with CF who meet their increased caloric requirements by consuming a balanced diet usually meet their increased protein requirements at the same time.

Most high-protein foods are of animal origin, including milk and milk products, meats, poultry, fish, and eggs. Legumes, such as peas, beans, and lentils, are also good sources of protein, especially when eaten with grain products.

Fat Intake.

In the past, people with CF were told to limit intake of fats and fatty foods. This was appropriate advice for that time, because replacement enzymes were not as effective as some of those available today, and malabsorption of fat was far harder to overcome.

However, today's replacement enzymes are more effective in promoting digestion and absorption of fats. In fact, it is now recommended that people with CF consume relatively high amounts of fat, for the following reasons:

• Ounce for ounce, fat provides more than twice as many calories as protein or carbohydrate.
• Conversion of fat to energy requires less oxygen than conversion of protein or carbohydrate to energy, putting less of a burden on the respiratory system.
• Generally, individuals with CF have a low blood cholesterol level and therefore do not have to restrict the intake of saturated fat and cholesterol.

Adequate dietary fat is also required for provision of essential fatty acids, a group of nutrients which the body requires for normal functioning.

Does this mean that the whole family should increase its consumption of fat? No! The average healthy American consumes too much fat already. A balanced diet of normal foods should be prepared for the entire family. The CF person can then increase fat intake by adding extra fats at serving time, eating larger portions of the fatty foods, and consuming additional high-fat foods.

Salt Intake.

People with CF lose more salt (sodium chloride) in their sweat than other individuals. Their need for additional salt is usually met simply by increasing intake of normal foods in order to meet caloric requirements. However, if you live in a very hot climate, your physician may advise adding extra salt to foods or increasing intake of salty foods.

Vitamin and Mineral Intake.

People with CF who meet their caloric requirements by consuming a well-balanced diet, and whose fat absorption is well-regulated, rarely develop vitamin and mineral deficiencies. However, because absorption is not optimal even at correct levels of enzyme replacement, supplementation is recommended.

Vitamins are absorbed most effectively when taken with fat-containing meals and pancreatic enzyme supplements. Infants and children up to 2 years old should take a liquid multivitamin preparation. Children ages 2 to 8 years need a standard multiple vitamin providing 100 percent of a healthy individual of the CF child's age. Older children, adolescents, and adults need 1 to 2 tablets of a standard adult multiple vitamin preparation every day.

High-potency multivitamin supplements are specially formulated to meet the needs of people with CF with poor dietary fat absorption. These supplements are indicated for use solely under medical supervision in CF people who do not obtain sufficient fat-soluble vitamins A, D, E, and K.

Additional supplementation with any vitamin or mineral beyond this level is recommended only if a specific need is recognized by your physician.

Modifying intake of regular foods.

Whenever possible, people with CF should meet their nutritional requirements by eating a balanced diet of everyday foods.

Start with a well-balanced diet for a healthy person of the same age. Then, if caloric and nutrient requirements are to be increased, modify intake by following these four steps:

1) Increase portion sizes.

2) Add snacks and "mini-meals," especially at night. Good choices are:

• fruit and nuts.
• Jam or jelly with buttered toast or cheesecake, pudding, and other dessert food.
• Cold cuts, pizza, or left-overs.

3) Emphasize high-calorie, nutritious food at mealtime and snacktime. Serve as many high-protein, high-calorie foods as possible, including:

• Whole-milk products, such as yogurt, cheese, custard, and pudding.
• Beverages made with whole milk, light cream, or undiluted evaporated milk, such as milkshakes, malteds, cocoa, eggnog, and instant breakfast.
• Nuts and nut butters (especially peanut).
• Meat, fish, poultry, or eggs prepared with added fat (see the hints on adding fat below) or in a mixed dish with another high-calorie, high-protein food (such as lasagna with meat and cheese).

At the same time, you may want to limit intake of foods that are filling but not very high in calories or needed nutrients. These include clear soups, tea, coffee, and low-calorie beverages.

4) Add extra fats. Remember, a little extra fat adds a lot of extra calories! Try these ideas:

• Put extra butter and margarine on bread products, cooked vegetables, hot cereals, pancakes, pasta, baked and mashed potatoes, rice, and other foods at serving time.
• Serve whipped cream or ice cream as a topping on desserts, cocoa, waffles, and other foods.
• Use extra mayonnaise on sandwiches and in salads such as tuna, potato, and macaroni.
• Use sour cream as a topping for fruit baked potatoes, fish, chili, and other foods.
• Serve dips made from sour cream and mayonnaise with fresh vegetables and snack foods.
• Use extra salad dressing; avoid lo-cal or reduced-calorie dressings.
• Serve generous portions of gravies and sauces.
• Use creamed soups instead of clear bouillon broth.

Adding extra fats is especially important because fats provide more calories per unit than carbohydrates. Proteins and fats are also essential for the body to properly absorb vitamins A, D, E, and K.

Your nutritionist will be glad to give you further suggestions, as well as special recipes, for nutritious, high-calorie treats.

Dietary supplements.

Several dietary supplements can be used to increase intake of calories and important nutrients.

Some common milkshake-like dietary supplements are Ensure, Magnacal ,Sustacal ,Enrich, Isocal, Osmolite and Scandishake . These nutritionally balanced liquids are slightly different in composition, but each is high in calories, protein, and other important nutrients. Most come in two or more concentrations, providing anywhere from 240 to 480 calories per eight-ounce can. All are commercially available in a variety of flavors.

Sustacal and Forta puddings are similar in nutritional calories per five-ounce can.

None of these pre-mixed, canned supplements requires refrigeration before serving. They can be served either with meals or as highly nutritious snacks, both at home and away.

Ask your nutritionist or physician for recommendations on which supplements to use and where to get them.

Increasing intake when eating is not enough.

It is not always possible or practical for people with CF to meet their increased caloric and protein requirements by consuming table foods and supplements. When eating is not enough to maintain good nutritional status and normal growth and development, your physician may suggest other types of feedings.

One option is tube feeding, which delivers liquid supplement directly to the stomach. Tube feedings may be given overnight as an adjunct to usual food intake. Another option is delivering nutrients directly to the bloodstream, through an intravenous tube.