Nutrition for children with CF

Why does my child struggle to gain weight? Healthy portion sizes

Good nutrition is very important for people with cystic fibrosis. We know that children who are better nourished have better growth and weight gainand, therefore, are more resistant to infections

There are two main reasons why children with cystic fibrosis may struggle to gain enough weight: 

  1. Most children who have cystic fibrosis are not able to breakdown and absorb the foods they eat as well as other children. This is because they do not produce the pancreatic enzymes that are needed to digest food, especially fat, so they struggle to get all the energy out of their food.
  2. The low-grade inflammation that children with cystic fibrosis have from a young age means they have higher energy requirements than usual. 

Therefore, most children with cystic fibrosis should have a diet that is higher in calories than other children their age who do not have cystic fibrosis.

Nutrition support

Lots of children with cystic fibrosis can meet the additional energy requirements by modifying or fortifying their normal family meals:

  • Add extra butter, mascarpone or cream to mash potatoes and pasta
  • Pop a handful of grated cheese on the top of meals
  • Mix a teaspoon of vegetable or olive oil into vegetables
  • Put a large amount of butter on toast, wait for it to melt in then add another layer!
  • Use full fat dairy products (blue top milk, non diet yoghurts)
  • Snacks between meals (but not too close to meals, try before bed)…peanut butter on toast, crisps and dips, flapjacks etc
  • Have a pudding with each meal as well, include pastry, crumble, sponge puddings, mousse and ice-cream

Sometimes the dietitian may suggest that a child with cystic fibrosis should have a high-calorie drink between their meals in order to boost their calorie intake. Some of these supplement drinks come on prescription from the GP. 

Or, you could try being creative and making your own:

  • Five ripe strawberries
  • Half a banana
  • Three tablespoons of chocolate milkshake flavouring (such as Nesquick or Crusha) or some honey
  • One tablespoon double cream
  • 250ml of full fat milk

Blend all this together then add a scoop of ice-cream! 

Occasionally, people with cystic fibrosis are unable to meet their increased energy requirements even though they are trying to eat as much as they can. At this point the doctor or the dietitian may suggest that a tube feed is required to deliver extra nutrition from special milk, usually given overnight, but sometimes during the day as well. If you feel this topic may be relevant to you or your child, please talk to a member of the hospital team next time you visit.


Most people with cystic fibrosis are not able to produce enzymes from their pancreas in order to digest their food. This is because the thick sticky secretions that affect people with cystic fibrosis block the small tubes that the enzymes flow through. We call this "pancreatic insufficient" and a person's pancreatic status will be tested at diagnosis through a stool (poo) sample. 

Without enzymes most patients struggle to gain weight because they do not absorb the nutrients in their diet very well. They usually suffer from offensive oily stools and tummy aches. People who are pancreatic insufficient sometimes have a big increase in appetite to compensate for the calories that they are not able to absorb from the foods they eat. We notice this quite a lot in babies. 

If you are pancreatic insufficient you will be prescribed enzymes to replace those that you can not make yourself. The brand we use at Royal Brompton is called Creon. There are some other brands available, especially outside the UK. 

Enzymes contain lipase (to digest fat), amylase (to digest carbohydrate) and proteases (to digest protein). These enzymes are coated in a protective layer so they look like little beads. This is so they do not get denatured by the stomach acid and can get to the intestines without being damaged. Babies will be given this on a very small spoon of apple puree, and as they get older it will be changed to yoghurt until they are old enough to learn to swallow enzyme capsules

Generally, the amount of Creon given is individually based on a person's age and symptoms, but is also often fine-tuned around the amount of fat that is in the food eaten. Talk to the dietitian if you need more help and advice on enzyme dosing

There are some foods (that do not contain fat) that are possible to consume without having any enzymes. These include most non-milk-based drinks like water, fizzy drinks and juice, as well as boiled and jelly-based sweets, fruits and vegetable (except olives and avocados), jelly, jam and honey.

Malabsorption Bristol stool chart

If you forget to take your enzymes or your dose is not quite right for you, you may notice some of the following symptoms: 

  • tummy aches, pain, bloating and wind
  • pale, floating stool that quite often will not flush away
  • oil (orangey) present in the water in the toilet after a bowel movement
  • needing to go to the toilet to open your bowels a lot (more than two or three times a day)
  • not gaining as much weight as expected.

Your dietitian or doctor might ask you to look at your poos and talk about how formed they are. You can use the chart at the left to help describe them.


People with CF need more salt in their diet especially in hot weather or if they are doing lots of exercise that makes them sweat. If we have a very warm summer, you are planning a hot holiday abroad then talk to your child’s doctor, they may need to be prescribed a salt supplement. As a general rule, it is a good idea to get into the habit of adding some extra salt to your child's meals (do this at the table, so that you are not adding unnecessary salt to your own diet), or having some salty snacks.

Here are some ideas:

  • Use salted butter on toast and vegetables
  • Marmite or Bovril
  • Soups and stock cubes in cooking
  • Crisps and cheese straws as snacks
  • Add salt at the table so the whole family doesn’t get too much


Most children should try and drink six to eight cups of drink per day. It is important for children with cystic fibrosis to stay hydrated, especially in hot weather. This can help to loosen secretions when doing physiotherapy.