The majority of people suffering from cystic fibrosis have an increased need for certain vitamins and sodium because this genetic disease is characterised by a lack of pancreatic enzymes, which in turn will result in poor absorption of most nutrients.
If these individuals have impaired fat absorption, they also won't obtain adequate supplies of the fat-soluble vitamins from their diet.
The four vitamins that are classed as fat-soluble are vitamins A, D, K and E. Low levels of these vitamins have been reported in the majority of people with cystic fibrosis. Individuals who are at particular risk include those with poorly controlled malabsorption, poor dietary adherence, accompanying liver disease and bowel resection.
People with cystic fibrosis may thus primarily suffer from a lack of vitamins A, D and E. Vitamin K deficiency may also occur as a result of long-term use of antibiotics, concomitant liver involvement and general nutrient malabsorption.
Vitamin E is an important antioxidant that protects the body against cell damage. Most western diets tend to be deficient in vitamin E, so people with cystic fibrosis are exposed to an even greater risk of developing a deficiency of this vitamin.
Supplements are usually indicated and should be discussed with a dietician. Vitamin E deficiency is also responsible for a condition known as haemolytic anaemia that occurs in babies with cystic fibrosis. This type of anaemia can usually be controlled by giving the baby 100mg of vitamin E a day.
People with this condition require the following fat-soluble vitamin supplementation on a daily basis:
In general, these individuals should receive between one and two times the recommended daily allowance (RDA) per day
- Vitamin A: 3500 and 7000 International Units (IU) for women and 4500 to 9000 IU for men
- Vitamin E: up to 30mg a day for both men and women
- Vitamin D: 5-10mcg per day for adults
- Vitamin K: up to 5mg twice a week for adults on long-term antibiotic therapy
As people with cystic fibrosis usually don't require supplementation with other vitamins (B-complex and vitamin C, which are not fat-soluble), individual vitamin supplements may be required. Discuss vitamin supplementation with your pharmacist and dietician, so that you can obtain the greatest benefit without having to buy a variety of supplements.
People with cystic fibrosis tend to excrete much more sodium in their sweat than normal and may thus develop a sodium deficiency. However, most people following a western diet will ingest sufficient sodium to meet these requirements.
Babies and small children may need to have some additional salt, especially as breast milk and baby formulas and foods are low in sodium content. It's been suggested that an additional 1/8 to 1/4 teaspoon of salt should be added to the diet of infants and young children. This amounts to about one pinch of salt a day.
Adults with cystic fibrosis need only supplement their normal salt intake if they sweat a great deal or suffer from diarrhoea. In such cases, doses varying between 250mg to 2g are taken two to three times a day with adequate liquids.
Other minerals usually don't need to be supplemented, but the mineral status of these individuals must be monitored to check for low iron and zinc stores, low magnesium levels and lack of calcium, which can lead to withdrawal of calcium from the skeleton, resulting in osteoporosis and weakened bones.
Enzyme replacement therapy
One of the most important supportive therapies for people with cystic fibrosis is the supplementation of pancreatic enzymes to promote normal digestion and absorption of vital nutrients.
Enzyme replacement can counteract malabsorption and steatorrhoea (abnormal excretion of fat in the stools). Enzymes such as lipase (required for normal fat absorption) are usually prescribed by the treating doctor and need to be taken immediately before or during meals.
Medications such as Creon, Pankrease and Viokase, which contain amylase, lipase and protease enzymes are typical examples of enzyme-replacement products used in cystic fibrosis. It's essential that adult patients shouldn't chew or crush the capsules as this can decrease the efficiency of the enzymes.
For infants who are unable to swallow capsules, the microspheres inside the capsules can be sprinkled on slightly acid foods, such as apple sauce, or mixed with infant juices. The microspheres should, however, not be mixed with alkaline foods (milk, custard or ice cream), because the enteric coating may dissolve and expose the enzymes to stomach acid, which will inactivate them.
Thanks to the development of enzyme-replacement therapy, people with cystic fibrosis can lead a normal life and absorb adequate amounts of nutrients from the foods they eat.
Consult a dietician
Always keep in mind that dietary interventions in cystic fibrosis are a vital part of overall treatment. Neglect of this important facet can lead to deterioration of the person's condition, lack of growth and stunting in children, and serious secondary complications. The help of a clinical dietician can make a profound difference in the lives of people with cystic fibrosis.
(This article was based on an update on cystic fibrosis and nutrition, published by the Nutrition Information Centre of the University of Stellenbosch, NICUS.)