Jan, 2001. Nutritional problems [online]. Seacroft and St James's University Hospitals, Leeds, UK. Available from http://www.cysticfibrosismedicine.com

The secretion of digestive juice from the pancreas is severely reduced in most patients with cystic fibrosis from an early age and unless treated with pancreatic enzymes, digestion and absorption of food is severely impaired. Inadequate absorption of food from the bowel will lead to unpleasant digestive symptoms, malnutrition, poor growth and specific deficiencies of the fat soluble vitamins A, D & E. (Littlewood & Wolfe, 1994). There is evidence that well nourished patients have a better outcome (Corey et al, 1988). It is therefore essential that patients with CF have an adequate energy intake and take effective pancreatic enzyme and fat soluble vitamin supplements (Littlewood & Macdonald, 1987; Littlewood & Wolfe 1994; MacDonald, 1996).

Nutritional requirements: The energy requirements of patients with CF vary widely and generally increase with age as disease severity increases. Energy requirement depends on the degree of control of intestinal malabsorption, increased energy expenditure from chest infections, and possibly on an additional increased energy expenditure related to the CF mutation. Providing malabsorption is adequately controlled in infancy, energy requirements may be normal. In comparison an older child, with incompletely controlled malabsorption and poor respiratory function may have energy requirements in excess of 150% (Littlewood & MacDonald, 1987) of the normal estimated average requirement (DHSS, 1991). All patients should be seen regularly by a dietitian who is experienced in the management of CF and who will tailor dietary advice to individual needs. Dietary fat should never be restricted as this nutrient is essential to achieve a good calorie intake and therefore a normal nutritional state and growth (Corey et al, 1988). Patients should be encouraged to take foods that are high in calories, such as fried foods, crisps and chocolate and those rich in protein such as milk, cheese and eggs. Many of these foods are also good sources of calcium, which is important in keeping bones healthy and in promoting good growth. Unfortunately, many patients do not manage to meet their increased energy requirements (Buchdahl et al, 1989; Morrison et al, 1994; Bentur et al, 1996; Kawchak et al, 1996). In order to optimise intake the diet of individual patients must be assessed regularly to ensure energy requirements are met. Ideally, a four to five day dietary diary should be recorded every one to two years or more frequently if growth is poor. This provides an estimation of dietary adequacy. The dietitian will then be able to advise on the most appropriate ways of increasing an individual patient's energy intake if this is necessary. If a patient's enzyme intake is also recorded alongside their food record the adequacy of enzyme dosing may also be assessed.

Evaluation of growth: Weight and height must be recorded at every clinic visit (minimum every three months). For children, the measurements must be plotted on the appropriate percentile charts so that growth progress can be closely monitored. Height should also be measured in adults as there may be a delayed growth spurt if nutrition has been poor and is then improved or if puberty is delayed. For adults, measurements must be converted to body mass index (BMI). In addition, head circumference should be measured and plotted on the centile chart for children under five years of age. Recently there has been increasing concern regarding the health of bones. All older children and adult patients with CF should have a dual energy x-ray absorptiometry (DEXA) scan for measurement of bone mineral density.

Feeding infants and toddlers: Most infants with CF will thrive on either breast milk or a standard infant milk formula. (Holliday & Allen, 1991; Simmonds, et al, 1994; Ellis et al, 1998). Breast milk has many potential advantages. It is easy to digest and therefore should be encouraged if the infant is thriving. A predigested medium chain triglyceride containing formula such as Pregestimil or Pepti Junior may be beneficial for infants who have undergone bowel resection following meconium ileus or for those who have a co-existing cows’ milk protein intolerance (Hill et al, 1989). The importance of monitoring growth in the first months of life cannot be over-emphasised. If the infant is 'failing to thrive', despite optimising their milk intake and pancreatic enzyme supplementation, additional energy supplements, e.g. Maxijul, Duocal may be added to the milk. The dose of the supplementation will be advised on an individual basis by the dietitian. Alternatively a higher energy infant formula e.g. SMA High Energy, Infatrini may be prescribed. If a baby appears exceptionally hungry, weaning a little earlier than is usual, at approximately three months may be advised. This may help to achieve a higher energy intake. Any method to achieve a higher energy intake during infancy should always be advised on an individual basis, taking into account the infant’s weight gain, fluid intake, absorption and hunger. During infancy, all pancreatic insufficient infants are given a standard strength, acid resistant pancreatic enzyme preparation (Creon 10000, Creon micro, Pancrease). The capsules are usually opened and the microspheres mixed with a few drops of milk or fruit puree and given by spoon at the beginning of the feed. A starting dose of ¼ to ½ capsule per feed is usually used. As requirements vary greatly, doses are then re-assessed regularly by the dietitian. Once a normal weaning diet is introduced the dose of enzymes given should vary according to the fat content and quantity of food eaten by the infant. By the end of the first year a normal weaning diet should have been introduced. As with all infants the breast milk or infant milk formula feeds may be changed to full-fat cows' milk at one year of age. Progressively the diet becomes more varied and therefore the need for enzyme variation according to the fat content of the food becomes greater. Around this time there is often a great deal of emphasis placed on the importance of achieving a good dietary intake. As a result of this some infants and toddlers may develop behavioural problems related to their feeding. Unless carefully and tactfully handled this problem can persist for a number of years resulting in a poor dietary intake and growth. It is essential that parents are able to voice their concerns regarding this behaviour and that advice is available for them.

Management of feeding behaviour problems (FBPs): Given the understandable parental concern regarding an adequate energy intake, children with CF are 'at risk' of developing FBP. Such problems have been found in over 70% of children (Sanders et al, 1997). The Leeds unit recently started screening for FBP using a modified version of the Behavioural Paediatric Feeding Assessment Scale (BPFAS) (Crist et al, 1994). FBPs consist of both disruptive child behaviours e.g. food refusal and, inappropriate parental responses e.g. shouting or making a second meal if the first is refused. Below are a few tips to help minimise the problem:

Try and have family meals, so children learn correct feeding behaviour.

Never lose your temper when food is refused. In the child’s eyes any reaction is attention. This will encourage the bad behaviour.

Limit meal times to 30 minutes. Research has shown that allowing mealtimes to drag on rarely results in any more food being eaten. After 30 minutes remove the food without comment, and wait for the next meal/snack time.

Never produce a second meal if the first is refused.

There must be a consistent approach from all who are involved with feeding. Parents who are worried about their child's feeding behaviour or interested in the BPFAS should ask for further advice from the dietitian and/or psychologist.

Feeding of school age children: With increasing age, there are new issues for the child with CF. Food is often used by the child as an effective tool to obtain parental attention and behavioural food refusal continues to be a common problem in this age category (Stark et al 1997). By school-age most children will manage to swallow their enzymes whole. The child is encouraged to always carry enzymes with them for snacks as well as meals and to be aware of which foods do and do not need enzymes, e.g. non-fat items such as fruit gums. Some schools can find self-medication of this nature a problem and it is often necessary for the CF liaison nurse/dietitian to discuss the need for pancreatic enzymes and dosages with staff. Having to take enzymes is usually the first time a child is likely to notice they are different to their peers. This can result in problems of acceptance of their condition and compliance. Increasing age increases the likelihood of lung infection, worsening chest symptoms and increased energy requirements. Along with the additional energy requirement to support growth, dietary supplements can be useful at this stage, to achieve an adequate energy intake. Supplementary feeding via nasogastric tube or gastrostomy may also be necessary to achieve good energy intake in some patients. Again this raises new and difficult issues for the child with CF (Levine 1998).

From adolescence: Adolescence is a time of change. Teenagers have a profound desire to become independent and to make their own decisions. They are likely to experiment, test limits and take risks. Food choice is one likely target for testing this independence. Poor adherence to enzyme, vitamin and nutritional supplementation is common and compromise is essential to minimise the consequences of this rebellious time whilst encouraging increasing independence.The body’s demand for nutrients at this time of rapid growth is relatively high and whilst parents may feel their teenager exists solely on junk food and snacks it should be remembered that these foods can still contribute significant amounts towards their nutritional intake. The important goal is to maximise growth potential. Recent work has suggested that despite our continuous emphasis on dietary intake and weight gain, adolescents and young adults with CF show eating behaviour and body image perceptions similar to healthy peers (Abbott et al, 1999; Abbott et al, 1999).

Dietary supplements: If a patient’s weight gain is inadequate or appetite poor, dietary supplements may help to improve the energy intake. Forty-one percent of our clinic population are taking these supplements at any one time (Unpublished data, Wolfe et al, 1995). There is a wide variety of supplements available including calorie only supplements e.g. Maxijul, Polycal and Duocal, calorie and protein only supplements, e.g. Scandishake, semi-complete supplements, e.g. Enlive and Fortijuice (fruit based), and nutritionally complete supplements, e.g. Ensure Plus and Entera (milk based). All of them are available on prescription. The type and amount of supplement recommended depends on the patient’s age, preference and requirements, and should therefore be prescribed on an individual basis by the dietitian. It is usually necessary to alter the flavour and type of supplement periodically to help prevent taste fatigue. The supplements should be taken in addition to normal food to increase the total daily energy intake. They should not replace a meal. Ideally they should be given with a snack between meals or as a drink after meals. Our own experience (Wolfe et al, 1995) and a multicentre UK trial (Skypala et al, 1998) support their use.

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