Paediatric cystic fibrosis (CF): vitamin D in children with CF

This leaflet is for at parents/guardians of children with CF to provide them with further information about vitamin D and vitamin D supplements.

What is vitamin D and why is it important in CF?

Vitamin D is a fat-soluble vitamin which the body needs to help absorb calcium and to develop strong, dense bones.

Low levels of vitamin D may contribute to low bone density and increase the risk of fractures. It is especially important to have enough vitamin D during the early teenage years and mid-twenties when most bone is formed.

Severe vitamin D deficiency can lead to rickets in children and osteomalacia (softening of the bones) in adults. Vitamin D may also play a role in lung health due to its anti-inflammatory properties; a good vitamin D status has been linked to improved lung function in CF.

Where is vitamin D found?

There are two types of vitamin D:

• Vitamin D2 (ergocalciferol) is found in some foods such as fortified margarine, full fat milk, eggs, naturally oily fish (for example salmon, herrings, sardines, pilchards, trout, mackerel), liver, fortified dairy products (some brands of yoghurt drinks, yoghurts, fromage frais, milkshake powders and processed cheese) red meat and some breads and breakfast cereals.
• Vitamin D3 (colecalciferol) is known as 'the sunshine vitamin’. This is because our skin can produce vitamin D from the sun’s ultraviolet light (UVB) rays.

Both types can be given as a supplement but vitamin D3 is given most commonly as it is thought this may be better at increasing and keeping good levels of vitamin D.

Why do children with CF need more vitamin D?

All infants and children (whether or not they have CF) are at risk of having low vitamin D levels due to low dietary intakes of vitamin D and lack of exposure to sunlight. Children with darker skin produce less vitamin D from sunlight than those with lighter skin.

Vitamin D deficiency and low vitamin D levels are common in people with CF for several reasons including: reduced absorption of vitamin D from foods (in those who need enzymes); having a low weight (this reduces the amount of vitamin D that can be stored in fat tissue); and reduced levels of sunlight exposure. It is for this reason that a higher blood level of vitamin D is aimed for in children with CF. Children who do not need to take enzymes may not need as much vitamin D as those who do need to take enzymes.

How can vitamin D be increased?

Diet

It is helpful to include foods rich in vitamin D (see above) as often as possible in your infant or child’s diet. Aim to give naturally oily fish twice a week for example in fish cakes, sandwiches, on toast, in pasta sauces or eaten whole. Some fish are available tinned or smoked or ready cooked in sauces such as curry, chilli, spicy tomato or mustard.

Sunlight

Most people make enough vitamin D by being out in the sun for short amounts of time. As a guide, let your child have safe exposure to the sun on their arms and face without sun cream for about 15 to 20 minutes two to three times a week between April and September.

Please be aware that some medications (eg Ciprofloxacin, Voriconazole) cause your child’s skin to be extra sensitive to sunlight. If your child is taking these medications, or your child experiences sun sensitivity, they should avoid exposure to sunlight.

When is a vitamin D supplement needed?

As foods only contain small amounts of vitamin D and it is not always possible to get enough vitamin D from the sun, most children also need to take a supplement to ensure they get enough.

All infants and children with CF who need to take enzymes (Creon) need to take a vitamin D supplement from birth.

The Department of Health recommends all infants who are being breastfed (whether or not their mother is taking a vitamin D supplement) and all children aged six months to five years are given a vitamin D supplement every day. (Babies who are fed infant formula do not need a vitamin D supplement if they're having more than 500ml formula milk a day, because infant formula is fortified with vitamin D and other nutrients.)

Some children with CF who do not need to take enzymes may also need to take a vitamin D supplement regardless of their age if the vitamin D level in their blood is low. The blood level will be checked by the dietitian and doctor following your child’s annual review and they will let you know if your child needs a supplement.

Ask your dietitian or local pharmacist for further information.

Which supplement does my child need?

The type, dose and frequency depend on your child’s age, whether or not they need to take enzymes and their blood levels of vitamin D. It is usually necessary for supplement(s) to be taken every day.

Children who don’t need enzymes

The Department of Health recommends a daily vitamin supplement containing 8.5 to 10 micrograms (400iu) vitamin D for breastfed infants and formula fed infants who are taking less than 500ml formula milk a day. They also recommend a daily vitamin D supplement containing 10 micrograms for children aged one to five years. This can be purchased over the counter from a pharmacy or from a supermarket.

Those who need enzymes

Infants and children who need to take enzymes will be started on the following vitamin D containing supplement at birth and will be requested on GP prescription Dalivit 0.6ml once a day.

• At age one, the doses may need to change, or an alternative liquid supplement may be recommended instead of or in addition to the Dalivit for example ‘Abidec’ or ‘Colecalciferol (vitamin D3) liquid.
• At around age two, and depending on your child’s blood test results, their vitamins may be converted to a multivitamin supplement called DEKAs plus liquid containing vitamin D.
• Once your child can swallow capsules, and depending on your child blood test results, DEKAs plus liquid can be changed to DEKAs essential capsules containing vitamin D.
• When your child is older (usually from around age eight) and depending on their blood test results, DEKAs essential capsules can be changed to DEKAs plus softgels containing vitamin D.

Some children may need to take individual vitamin D capsules instead of or in addition to the DEKAs multivitamins, depending on their blood test results.

Some children may also need to take a calcium supplement if their dietary calcium intake and/or bone density are low. As some calcium supplements also contain vitamin D, the above supplement(s) may need to be adjusted; the dietitian will discuss this with you.

It is important for all vitamin D supplements to be taken alongside a milk feed/ food and enzymes (if your child usually takes these); this helps the body to absorb the vitamin D.

How are vitamin D levels checked?

The blood tests taken at your child’s CF annual review will be used to check their vitamin D levels. Total vitamin D (25OH) is measured. This is the total combined level of vitamin D2 and vitamin D3. A level above 75nmol/l is the ideal target level in CF. Seasonal variation is considered.

The blood samples are analysed at Addenbrooke’s hospital and usually take about two weeks to come back. The dietitian will interpret the blood levels together with the consultant and write to you with the results and any recommended changes. They will give advice on increasing vitamin D from dietary sources and from the sun and they will advise on any adjustments to the supplements if required.

Can too much vitamin D be harmful?

Very high doses of vitamin D may cause hypertension, an irregular heartbeat, and excessive thirst. Toxic levels are rare and as far as we are aware, have not been reported in CF.