Early diagnosis of CF through neonatal screening (NS) gives the opportunity to prevent nutritional problems early in life (Shoff et al, 2006). Age at diagnosis is a critical determinant of nutritional status. The most consistently observed benefits of NS are nutritional (Farrell et al, 2001; Farrell et al, 2005; Sims et al, 2007). Most infants with CF will thrive on either breast milk or a standard infant milk formula (Holliday & Allen, 1991; Ellis et al, 1998; Farrell et al, 2001). Breast milk has many potential advantages. It is easy to digest, contains growth factors and may help to protect against infection. Therefore breast feeding should be encouraged if the infant is thriving. Exclusively breast feeding babies with CF for six months is associated with a decrease in disease severity based on less antibiotic use (Parker et al, 2004).
Approximately 15% to 20% of infants present with meconium ileus (blockage of the large bowel) and may have special nutritional requirements (Lai et al, 2000). If surgical resection is required (for removal of the meconium), cows’ milk protein intolerance may occur and a hydrolysed protein, medium chain triglyceride containing formula such as Pregestimil® or Pepti Junior® may be required. Gastro-oesophageal reflux is also common in infants with CF (Heine et al, 1998). Unless treated this may compromise growth and cause irritation to the lungs and wheeziness through reflux aspiration. Treatments include thickening feeds, using a pre-thickened infant formula, gastric acid suppression (Brodzicki et al, 2002) and motility stimulants.
Over 50% of the energy content of breast milk and infant formulae is derived from fat. Infants who present with obvious malabsorption should start pancreatic enzyme replacement therapy on diagnosis of CF. A delay in starting enzymes in this age group will have a devastating effect on nutritional status and growth. The importance of monitoring growth in the first months of life cannot be over-emphasised. A newly diagnosed patient should be seen every one to two weeks until treatment is established and they are thriving. Thereafter patients should be seen at least every two months. Providing malabsorption of fat is controlled, adequate weight gain and growth will be achieved in most infants who are breast fed on demand or receive 150-200mls (100-130kcal) per kg body weight/day of infant formula. If the infant is failing to thrive despite optimising their milk intake and pancreatic enzyme supplementation, a higher energy infant formula e.g. SMA High Energy® or Infatrini® may be prescribed. Alternatively additional energy supplements, e.g. Maxijul®, Duocal® may be added to expressed breast milk or infant formula. The dose of the supplementation should be advised on an individual basis by the dietitian. Weaning foods should be introduced at four to six months of age and a normal diet should be encouraged. If weight gain is poor methods to achieve a high energy/high fat diet should be advised on an individual basis, taking the infants appetite, fluid intake and absorption into consideration. Occasionally, additional sodium supplementation may be required if the infant is failing to thrive, especially if fed a normal infant formula which may have a low sodium content. The need for additional sodium may increase during the summer months due to increased sweating in hot weather. Deficiency should be confirmed by serum sodium levels and urinalysis (sodium <10 mmol/l). Supplementation with 1-2 mmol sodium/kg/day should correct deficiency or prevent deficiency in hot climates.
During the weaning process, pancreatic enzyme therapy should be tailored to the dietary fat intake and there should be close monitoring of fat absorption. By the end of the first year a normal weaning diet should have been introduced. As with non-CF infants, breast milk or infant 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, given the understandable parental concern regarding an adequate dietary intake, there is often a great deal of emphasis placed on the importance of achieving a good dietary intake. This can result in food being used to manipulate parents! Behavioural food refusal can become a problem (Duff et al, 2003). Unless carefully and tactfully handled, these behaviours can persist for a number of years, resulting in a poor dietary intake and poor growth. It is essential that parents are able to voice their concerns regarding this behaviour and that advice is available for them. Effective management of feeding behaviour problems has been shown to improve food intake and growth (Powers et al, 2005).
Management of feeding behaviour problems (FBPs)
Using a modified version of the Behavioural Paediatric Feeding Assessment Scale (BPFAS), (Crist et al, 1994) we have found a high number of children with CF who have FBPs (Duff et al, 2003). These behaviours 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:
• Encourage family meals, so your child is seated with other children/adults and will learn correct feeding behaviour
• Avoid distractions e.g. having the television on at mealtimes
• If your child is slow at eating, gentle encouragement will help
• Make food as attractive as possible
• Never lose your temper when food is refused. In the child’s eyes any reaction is attention. This will encourage the bad behaviour
• Encourage ‘good’ or ‘positive’ behaviour and give lots of praise for it
• 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. Otherwise the child will play people off against each other and the bad behaviour will persist
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
As children get older the likelihood of lung infections and worsening chest symptoms increase. This leads to greater energy requirements. Close monitoring of growth and nutritional status continues to be essential (Cystic Fibrosis Trust, 2002). If growth is poor, as well as optimising the intake of normal food and encouraging a high fat diet, the use of nutritional supplements should be considered. Supplementary feeding via nasogastric or gastrostomy tube may also be necessary to achieve a good energy intake in some patients, (Walker & Gozal, 1998; Oliver et al, 2004).
By school age most children will manage to swallow their enzyme capsules whole. As children get older they are encouraged to learn about their pancreatic enzyme replacement therapy and to always carry enzymes with them. Eventually the child will be able to take on the responsibility for enzyme dosing with meals and snacks and be aware of which foods do and do not need enzymes. 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 encouraging independence with this aspect of treatment 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 adherence to treatment.
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. The main growth spurt occurs during this period, although timing will vary considerably for each individual depending on such factors as gender, genetics and pubertal delay. The nutritional goal throughout is to maximise growth and ensure adequate weight gain. A recent study in our own clinic has compared children with CF to healthy schoolchildren and shown that weight gain and growth can decline dramatically during adolescence (White et al, 2007). Previous work has shown that malnourished adolescents have a marked decline in %FEV1, whereas lung function remains stable in adolescents of normal weight (Steinkamp & Wiedemann, 2002). Both studies highlight the need to target this age group with emphasis on the positive impact that weight has on lung function. Females with CF have increased resting energy expenditure independent of menarche (Barclay et al, 2007). Therefore intervention to maintain growth and nutritional status is essential to meet these increased requirements.
Energy and protein requirements will be greatest at the time of peak growth which occurs during adolescence, and under-nutrition can lead to stunted growth, delayed puberty and inhibition of bone development. Adequate intakes of all nutrients are essential but particularly iron, vitamin C, zinc and calcium. The latter is important in maximising bone density and has been shown to be a positive predictor of bone mineral status in children and adolescents with CF (Chan et al, 2001). Iron is also a key nutrient as a component of muscle and blood and achieving adequate iron stores is particularly important for girls when menstruation begins. Despite teenagers within our own clinic having higher intakes of these nutrients than healthy controls, they still have lower intakes of iron than recommended (White et al, 2007). Indeed, up to 62% of our adolescent/adult clinic population were iron deficient (Pond et al, 1996).
Balanced against this background of high nutritional requirements and rapid growth is an increasing need to become independent. Patterns of eating alter and while parents may feel their teenager exists solely on junk food and snacks, it should be acknowledged that this is normal and is an easy way to achieve the higher energy needs. Poor adherence to enzyme, vitamin and nutritional supplementation is also common and compromise is essential to minimise the consequences of this rebellious time whilst encouraging increasing independence. Encouragingly work suggests 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, 2000).
• Neonatal screening is associated with long-term improvement in nutritional status
• Most infants thrive on breast milk or normal infant formulae until weaning is introduced at four to six months of age
• Pancreatic enzyme replacement therapy should be commenced as soon as the diagnosis of CF is made in infants with obvious symptoms of fat malabsorption.
• Newly diagnosed patients should be reviewed every one to two weeks until treatment is established and they are thriving
• Individual assessment of nutritional needs should be reviewed regularly by a dietitian experienced in CF according to the clinical and psychosocial needs of the patient
• Advice should be given to avoid behavioural and adherence problems that may affect nutritional status
• Age specific dietary advice is required though out life
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