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Reactions to food

allergy; allergies; foods; reactions; anaphylaxis; chemical; protein; intolerance; immune; system; peanut; egg; soy; wheat; fish; shellfish; sesame; tree; nuts; milk; cows; colouring; preservatives; flavour; behaviour; hyperactivity;

Foods can cause a wide variety of reactions in children. A food allergy can be life-threatening in some rare cases, but most reactions to food are less severe.

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Foods may be blamed when they are not the cause of the problem, so it is important to get any illness or reaction checked by a doctor to be sure of the cause.

Types of reactions to foods 

Food allergy

A food allergy is a reaction to a protein in a food that is caused by the immune system. Food allergies are common in young children (about 1 in 30 preschoolers have an egg allergy, and 1 in 100 have a nut allergy). A reaction occurs whenever the child is given the food protein they are sensitive to.  Reactions caused by food allergies may happen immediately after the food is eaten or they may be delayed. 

In Australia most food allergies are caused by the following food proteins: egg, cows' milk, soy, wheat, peanut, tree nuts, fish, shellfish and sesame. It is possible to have allergies to other foods, but this is less common.

Food chemical intolerance  

Food intolerances are reactions to foods that are not caused by the immune system.  Food intolerances include reactions to chemicals in food such as to food colourings, preservatives and flavour enhancers or natural food chemicals called salicylates, amines and glutamines.  Reactions to food chemicals may happen soon after the food chemical is eaten or they may be delayed.

Carbohydrate malabsorption

Some children are not able to tolerate large amounts of the natural sugars present in foods. This can cause gut symptoms such as loose bowel actions, bloating and flatulence (wind). Lactose intolerance and fructose malabsorption are two common causes of carbohydrate malabsorption in children.

Food poisoning is a reaction to a poison in foods, often from bacteria. This is not covered in this topic.

Symptoms of food allergy

  • Local reactions - eg a red rash around the mouth where the food has touched the skin.
  • General reactions - skin rashes on other parts of the body, hives, swellings, vomiting, wheezing or other breathing problems, or in rare cases, collapse.

When a child has symptoms including breathing difficulties or collapse (due to low blood pressure), this is called anaphylaxis. (There are links to more information about anaphylaxis in the topic 'Anaphylaxis'.)

Alert!
If a child has had a severe reaction to a particular food (especially one involving breathing difficulty or collapse) it is most important to:

  • Avoid the food unless the child is being observed by a doctor.
  • Seek a medical review with your GP, and consider a referral to a specialist physician.
  • Avoid nuts and nut containing foods until advised otherwise by your GP or specialist physician.

What to do if you think your child has a food allergy

  • Stop giving your child the food causing the reaction. 
  • If your child has symptoms including breathing difficulties or collapse, seek emergency medical attention.
  • If you think your child might have a food allergy, see your doctor to help identify the trigger for your child's reaction, you should also
      • be educated regarding avoidance of the food,
      • have a first aid plan,
      • have information regarding longer term prognosis (what will happen in the future). 

A referral to a specialist might be required. 

  • Skin tests or blood tests can be useful to help work out which foods your child is sensitive to.

The food causing the allergy will need to be taken out of the child's diet (or in some cases, from the mother's diet if the baby is breastfed).

  • Make sure your child still gets a good balanced diet - if you are unsure about this an Accredited Practising Dietitian with experience in managing paediatric food allergy can help with planning your child's diet.
  • After a year or two challenges with the problem foods may be arranged. Your child is exposed to the food only with the doctor's supervision. If your child has had a very severe reaction to a food this would only be done in a hospital.
  • Ongoing severe allergies (eg to peanuts) can be a real problem. These children may need to carry adrenalin for use in an emergency, and have special care taken at childcare, preschool and school to protect the child.

Tests for food allergy

Skin Prick Testing and Specific IgE testing are tests that are commonly used to predict the presence of a group of allergies called “IgE mediated” allergies. An IgE mediated allergy has reactions caused by the presence of IgE antibodies to food.

Both of these tests are used by allergists to predict the likelihood of someone having an IgE mediated allergy to a food or an environmental allergen such as pollen or house dust mite. It is important to realise that these tests may be positive to allergens (foods or pollens etc) that don't have an effect clinically. There is no need to exclude foods from the diet if they don't affect the child.

  • Skin prick testing. A small amount of solution containing the allergen is dropped onto a tiny scratch in the skin, and the size of any reaction is measured.
  • Specific IgE testing. This is a blood test used to measure specific IgE (Immunoglobulin E) antibodies to an allergen.

Unproven Allergy Tests

Tests such as vega testing, IgG testing and hair analysis should not be used to predict food allergies in children.  More information about unproven allergy testing can be found on the Australasian Society of Clinical Immunology and Allergy (ASCIA) website, www.allergy.org.au.

Cows' milk allergy

Cows' milk allergy is an immune reaction to a protein in cows' milk. Children with cows' milk allergy will react to all sources of cow's milk protein.

Cows' milk allergy is different to lactose intolerance, which is the inability to digest lactose (milk sugar) properly.

What you can do

  • If you think your child might have a cows' milk allergy, see your doctor to help identify the trigger for your child's reaction, you should also
      • be educated regarding avoidance of the food,
      • have a first aid plan,
      • have information regarding what may happen in the future. 

A referral to a specialist might be required. 

  • If your baby is bottle fed, the doctor will usually recommend that you stop giving cows' milk based formula to the baby.
  • Sometimes soy formula is given instead. Occasionally a baby will also be allergic to soy and should be prescribed an extensively hydrolysed or amino acid based formula by their paediatrician or allergist.
  • Goat's or sheep milk are not recommended for managing cows' milk allergy as it is likely that the child will be allergic to them as well.
  • If changing the formula doesn't help, the problem may not have been due to allergy in the first place.
  • Breastfed babies may react to cows' milk in their mother's diet. Sometimes it is recommended that the breast feeding mother has a trial of a cows' milk free diet.  If there is no improvement in the baby's behaviour she should return to her normal diet, to keep herself healthy. If a mother needs to avoid cows' milk or other foods for some time, she should consult a dietitian to be sure she still gets a well balanced diet.

Peanut and tree nut allergy

Peanut and tree nut allergy is an immune reaction to a protein in peanuts or tree nuts.

Children with peanut allergy may also be allergic to other nuts (such as almonds and cashew nuts) or other legumes such as lentils and chick peas. 

It is possible to have an allergy to a single type of nut or several different nuts. Children eating nuts that they can tolerate should take care that they do not accidently eat the type of nut that they are allergic to.

What you can do

  • If you suspect your child has a peanut or nut allergy, even if it seems mild, check with your doctor to help identify the trigger for your child's reaction.  You should
      • be educated about how to avoid peanuts in your child's diet,
      • have a first aid plan,
      • have information regarding longer term prognosis. 

A referral to a specialist might be required.

  • If your child does have a peanut or a nut allergy, you will need to ensure he or she avoids all foods that could contain nuts. Check labels of all commercial foods carefully.
  • Do not use peanut or other nut oil on your baby's skin (eg for massage or dry skin).
  • More information regarding peanut, tree nut and seed allergy can be found on the ASCIA website 
    http://www.allergy.org.au/patients/food-allergy/peanut-tree-nut-and-seed-allergy  

 

Food chemical intolerance

Food intolerances are reactions to food which do not involve the immune system. Food intolerances include reactions to natural food chemicals, (eg salicylates, amines and glutamates), or to food additives (eg preservatives, colourings and flavour enhancers).

Symptoms of food intolerance include skin conditions (eg eczema, hives), gastrointestinal problems (eg vomiting, diarrhoea) and respiratory problems (eg wheeze). Anaphylaxis can occur due to food chemical intolerance, but this is less common. Food chemicals, in particular artificial food colourings and preservatives, may affect behaviour in some children.

It is important to make sure that your child's symptoms are not due to food allergy, which is an adverse reaction to food involving the immune system. No skin or blood tests are available to diagnose food chemical intolerance.

If you suspect your child's symptoms may be caused by a food chemical intolerance there are several steps in the diagnosis:

  • An elimination diet is used to remove the suspect chemicals from the diet. It is important that this is only done with the help of a doctor and dietitian because growing children need good nutrition. If there is no improvement in symptoms, the diet should be ceased. 
  • If the child's symptoms improve on the elimination diet it is important to have a number of food chemical challenges to see which (if any) food chemical was the cause of the reaction. (The child is given small amounts of chemicals that are in the food that might be the problem to see if there is any reaction.)  
  • Children with severe reactions to any food should not have food challenges without the supervision of a doctor.
  • After the food chemical challenges a normal diet is reintroduced, avoiding any problem food chemicals.

Diagnosis of a food chemical intolerance is best managed with a team approach including your child's doctor and an Accredited Practising Dietitian with experience in managing paediatric food intolerances.

 

Frequently asked questions

Can behaviour problems be due to diet?

  • Studies provide only a little support for the theory that food or chemical intolerance may be part of the cause of behaviour problems in some children.
  • Only a few children seem to benefit if kept off certain foods, but if they are sensitive, then keeping off the foods may make a major difference to their behaviour.
  • The first step in working out whether foods are affecting behaviour is as easy as limiting highly coloured and preserved foods in the diet. These foods include soft drink, lollies and packaged snack foods.
  • Taking out the foods which seem to be causing the problem and then gradually trying them again, one by one (elimination diet and challenge) may be tried with a doctor's help.
  • High sugar levels in the diet have not been proven to cause difficult behaviour, even though some high activity children have more difficult behaviour after a party. It is probably the excitement of the activity that causes the misbehaviour.
  • Many high activity children are sensitive to the effect of small amounts of caffeine (in coffee, cola drinks and chocolate). It can be worthwhile avoiding these drinks and foods.

Are allergies related to immunisations?

Being immunised does not cause a child to develop allergies.

All vaccines recommended on the standard Australian Immunisation Schedule for children can be given to children with food allergies, including those children with egg allergy. These vaccines include vaccines which protect against Diphtheria, Tetanus, Whooping Cough, Polio, Haemophilus (Hib), Hepatitis B, Pneumococcal, Meningococcal C, Measles, Mumps, Rubella and Chickenpox.

The MMR (Measles, Mumps and Rubella vaccine) can be given to children who have a history of anaphylactic reactions to eggs. Anaphylactic reactions to any vaccine including the MMR are very, very rare.  Anaphylactic reactions to the MMR vaccine are not more common in children who have a severe egg allergy.

A history of anaphylaxis to egg (generalised hives, swelling of the mouth or throat, difficulty breathing, wheeze, low blood pressure or shock) usually means a person should not have influenza, yellow fever, and Q fever vaccines.   But if there is a significant risk from these diseases your child should be seen by an allergy specialist who can decide on the risk of receiving these vaccines and may give these vaccines under observation.

Can food allergy be prevented?

The tendency to develop allergies (atopy) is inherited. Allergies tend to run in families.

If there is a strong history of allergies in the family, talk to your doctor or paediatrician to discuss what might reduce the risk of your child having food allergies. This is an area of active research world wide, and recommendations are changing as more evidence becomes available.  See the ASCIA website for the most up to date recommendations  http://www.allergy.org.au  

Managing food allergies away from home - eating out, childcare, preschool (kindergarten) and school

If a child has a food allergy, there are some things that can be done at the centre or school that can reduce the risk of accidental exposure to the food.

Some of the basic 'rules' that can reduce the risks for child with food allergies include:

  • Provision of an up to date action plan for the child, and education of staff on how to manage a reaction if it should occur.
  • People responsible for food preparation should know about, and follow careful cleaning of surfaces and utensils to prevent cross contamination with the allergen.
  • Removal of a food from the school (eg from the school canteen) should only be done if recommended, in writing, by a medical specialist. The risk of a life threatening reaction from casual skin contact appears to be very low, although sometimes a child may develop a skin reaction (eg hives). Simple hygiene such as hand washing and bench-top washing are considered appropriate.
  • At school it is ideal that children with severe allergies should only eat lunches and snacks that have been prepared at home.
  • There should be no sharing of food, food utensils and food containers. However, other parents could also be asked not to send to school food containing the problem food (eg peanut butter), because peanut butter is sticky and can be transferred from the food to other surfaces.
  • Bottles, other drinks and lunchboxes should be clearly labelled with the name of the child.
  • The use of food in crafts, cooking classes and science experiments should be restricted according to the allergies of a particular child.

More information about managing children with severe food reactions in schools, preschools and childcare, can be found

Teaching children about their allergies

If your child has a food allergy it is important that they learn to always check with a parent or caregiver before eating a food.  As they get older teach your child how to read a food label.

Children with nut allergies should learn what different nuts look like.

Your allergy checklist

If your child has an allergy you should:

  • Have a clear, written plan about what foods (if any) to avoid.
  • Have an action plan about how to manage a reaction to a food, regardless of how mild the reaction is.
  • Have a follow up appointment to assess your child's allergy.

Action plans

Parents of every child with a food allergy should be given information about how to manage a reaction to a food, regardless of how mild the reaction is.  Up to date action plans may be accessed on the ASCIA website, www.allergy.org.au 

References

Australasian Society of Clinical Immunology and Allergy

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The information on this site should not be used as an alternative to professional care. If you have a particular problem, see a doctor, or ring the Parent Helpline on 1300 364 100 (local call cost from anywhere in South Australia).

This topic may use 'he' and 'she' in turn - please change to suit your child's sex.

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