Food allergies and food intolerance in children

Around 6 in 100 preschool and junior school children have some type of food allergy. You can learn about some of the commonest allergies here.

Allergic reactions in children in the first years of school are often caused by peanuts and tree nuts. This type of allergy does not usually go away as the child grows older. While peanut and tree nut allergies are more widespread now, allergy to fish has become slightly less common in recent years.

Pulses (dried peas, beans, lentils and chickpeas) and the commonest varieties of cereal grains (wheat, barley and rye) can also cause allergic reactions. Allergy to rice or maize is rare however. In young infants, milk or gluten may cause allergy or intolerance.

Antibodies in the blood cause allergy
The very first time a child comes into contact with a food it is allergic to, there will typically be no allergic reaction. This is because no antibodies to that food allergen have developed in the child's blood yet. However, a breastfed infant may have come into contact with cow's milk protein, for example, via its mother's diet long before it is weaned onto other foods. This is why babies may show symptoms of allergy to cow's milk the very first time they try a dairy product.

Food allergy symptoms in infants
If your child has a food allergy, you are likely to see an acute reaction within a few minutes. Children react in many different ways, but a skin rash or tummy ache is common. Some children may also suffer airways problems due to allergy.

Common symptoms are:
• rash or eczema
• nausea and vomiting
• stomach ache, diarrhoea or constipation
• itching and irritation in the mouth, swelling of the lips and in the throat

Severe allergic reaction – anaphylaxis
Most allergic reactions are mild and easy to deal with if you are well informed about them. However, a small number of individuals have severe allergic reactions. If an allergic reaction is so severe as to be life-threatening, it is called an allergic shock reaction, anaphylactic shock or anaphylaxis. Foods known to cause anaphylaxis include peanuts, almonds, shellfish, fish and milk. If your child becomes listless, pale and distressed after a meal – call the emergency services immediately.

Children often grow out of tomato intolerance
Food intolerance and food allergy are not the same.
An intolerance may be a one-off event if your child's immune system has been weakened by a recent infection. A rash and other skin reactions are not necessarily a sign of food allergy. Some children react to substances in red berries or tomatoes. So, it's good to wait to introduce these. Children typically grow out of this type of intolerance.

Wait to wean
If you breastfeed your baby, which is the ideal, or bottle-feed your baby infant formula exclusively for the first four to six months, this may help to prevent or delay hypersensitivity to certain foods.

breastfeeding is not thought to reduce the risk of allergy in the long term. However, it is believed that the risk of gluten intolerance in infancy is lower among children who are weaned slowly onto foods containing gluten.

If you suspect your child has an allergy
If you suspect that your child has a food allergy, if your child's growth is delayed or if many of the child's relatives have some form of allergy, you should consult a paediatric nurse or doctor about having your child allergy tested.

If you have just started weaning your baby onto solids, you can try eliminating certain foods such as milk for a time to see if there's any change. But consult a health professional first for advice on what to give baby instead of the suspected food allergen.

Children often grow out of milk allergy
Cow's milk allergy affects at least two per cent of all babies. But most of them grow out of this allergy by the age of three. Sometimes they develop other allergies instead, such as to eggs, pollen or dust mites.

Milk allergy can cause symptoms in the digestive system, skin, but also the airways. Treatment consists of a diet that completely excludes milk protein. This is not always easy, so you may want to consult a dietician. There are special infant formulas available for children with cow's milk allergy. These can be used as a milk substitute in home-made meals, including baby's first solids such as porridge.

Toddlers aged 1-3 years with milk allergy can be given oat milk, but you should avoid soy milk, as children with cow's milk allergy may become allergic to soy protein later. In rare cases, milk allergy can cause an allergic shock reaction in just 15 minutes – in this unlikely event, call the emergency services immediately.

Cow's milk allergy should not be confused with lactose intolerance, which is caused by a hypersensitivity to a natural sugar in cow's milk. Lactose intolerance is very rare in young children.

Gluten intolerance – coeliac disease 
Introducing tiny amounts of foods containing gluten gradually after 4-6 months of exclusive breastfeeding is believed to reduce the risk of gluten intolerance in infancy. It is also important to wean your child onto gluten slowly from infant formula.

About one to two per cent of children, and more girls than boys, are gluten intolerant. Gluten is present in the cereal grains wheat, barley and rye. Being gluten intolerant is not the same as being allergic to certain cereals. Your child may not show any sensitivity to gluten the first time he or she tries a food containing gluten, but much later on. Gluten intolerance is a life-long disease.

A number of children react strongly to even tiny amounts of gluten, while others are barely affected. Many gluten-sensitive children have delayed growth because they are unable to absorb nutrients properly. This makes it important to maintain a strict gluten-free diet.

Common symptoms in infants with glucose intolerance
• weight loss
• failure to achieve expected weight gain and growth
• poor appetite
• large loose bowel movements or constipation
• tiredness and lethargy
• swollen belly but slender arms and legs
• stomach ache

If you suspect that your child may be gluten sensitive, you should consult your doctor for a referral to have your child tested. Do not attempt a gluten-free diet before seeking medical advice. This may make it more difficult to diagnose the problem when your child then sees a specialist.

Nut allergy
Allergy to peanuts and tree nuts is very common and often starts at preschool or school age. The reaction occurs within a few minutes of the child eating the nuts. The commonest reactions are mild, such as mouth itching, rash and stomach upset.

A small number of children develop severe allergy. If a child is having difficulty breathing, or becomes tired and pale after eating nuts – call the emergency services immediately. These children may be at risk simply from breathing air containing traces of nuts. Peanuts and tree nuts (almonds, pine nuts, chestnuts, walnuts, cashews and many more) are not related to each other. A child who is allergic to peanuts may not be allergic to tree nuts, and vice versa.
Children who are allergic to pollens, such as birch pollen, may also react to nuts. This is called a cross-reaction and does not usually cause as severe symptoms as actual nut allergy.