As many as one in five adults and children, and probably one in three with behavioural problems, react allergically to common foods such as milk, wheat, yeast and eggs. The knowledge that allergy to foods and chemicals can adversely affect moods and behaviour in children has been known, and ignored, for a very long time. Early reports back in the 1980’s, confirmed by recent double-blind controlled trials, have found that allergies can affect any system of the body, including the central nervous system. They can cause a diverse range of symptoms including fatigue, slowed thought processes, irritability, agitation, aggressive behaviour, nervousness, anxiety, depression, ADHD, autism, hyperactivity and learning disabilities. These types of symptoms can be caused by a variety of substances in susceptible children, though many have reactions to common foods and/or food additives. 

Allergy, Intolerance or Sensitivity?

These days people use the terms food allergies, food intolerances and food sensitivities almost interchangeably. So, what is the difference between these terms? The classic definition of an allergy is ‘any idiosyncratic reaction where the immune system is clearly involved’. The immune system, which is the body’s defence system, has the ability to produce ‘markers’ for substances it doesn’t like. The classic marker is an antibody called IgE (immunoglobulin type E). When the offending food, called an allergen enters the bloodstream and meets its IgE marker, it triggers the release of chemicals including histamine that cause the classic symptoms of allergy – skin rashes, hay fever, rhinitis, sinusitis, asthma, eczema, swelling in the face or throat and anaphylaxis. All of these ‘IgE-mediated’ reactions are immediate and severe and may be life-threatening. If your child has this type of allergy, you probably already know about it and are strictly keeping your child away from the offending food.

The most common type of food allergy involves a different marker called IgG. The difference here is that IgG reactions may take anywhere from an hour to three days to show themselves, are often less immediately dramatic in nature and are therefore much harder to detect. So it’s more likely your child will be continuing to eat these foods on a regular basis, especially as we’ve seen above the foods involved are very commonly eaten.

Food intolerances and sensitivities are reactions to food where there is no measurable antibody response. Examples of these include lactose intolerance, where a child lacks the enzyme to digest lactose (milk sugar), usually resulting in digestive symptoms such as diarrhoea and abdominal discomfort or intolerance to the flavour enhancer MSG, which makes some kids hyperactive.

The Top Ten Allergens

Most food allergies develop in reaction to the protein in food, and particularly foods we eat most frequently. Top of the list is wheat, probably because it contains a substance called gliadin, which irritates the gut wall. Gliadin is a type of gluten, a sticky protein that allows pockets of air to form when risen with yeast, which is how bread is made. Eating a lot of wheat products isn’t good for anyone, especially if you’re child has developed an allergy. The connections between wheat allergy, autism and ADHD are well established.

Rye, barley and oats contain much less and different kinds of gluten. For this reason, some children who are allergic to wheat can tolerate rye, barley and oats and some children who are allergic to wheat, rye and barley can tolerate oats, which contains no gliadin.

Dairy produce causes allergic reactions in many children. This includes cheese and yoghurt. Some children can seemingly tolerate goat’s or sheep’s milk but not cow’s milk; however, this is more likely due to their consuming less dairy overall. The symptoms of dairy allergy are many and varied but often include a blocked nose, frequent colds, bloating and indigestion, ‘thick’ head, fatigue, earaches and headaches. Any food can cause an allergic reaction but the most common include milk, eggs, wheat and other gluten grains, yeast-containing foods, shellfish, nuts, peanuts, garlic and soya.

Of all the avenues so far researched, the link between behavioural problems and allergy is the most established and worthy of pursuit in any child displaying hyperactive behaviour or unexplained mood swings.

Testing for Allergies

If your child has a history of infantile colic, eczema, asthma, ear infections, hay fever, seasonal allergies, digestive problems (including bloating, constipation and diarrhoea), frequent colds and any behavioural or learning problems, then you should suspect a delayed food allergy. In which case, you should have him or her tested to identify which foods are the culprit. The best test is called IgG ELISA and uses a finger-prick blood sample and a home test available from Yorktest. Testing is best done under the guidance of a nutritional therapist (BANT registered) or allergy expert who can then devise a diet for your child that avoids any allergy-provoking foods and can also recommend suitable alternatives.

An alternative method of identifying food allergies is an elimination and challenge diet. This involves removing any likely culprits from your child’s diet for a period of time (from two weeks to three months may be required) and noting any changes in behaviour, mental and physical symptoms. Then reintroduce the foods in a controlled way, again monitoring closely for any changes in behaviour, mental and physical symptoms. This method has many shortcomings because the range of foods that a child can react to is so broad.

Foods that invoke an IgE type immediate and severe reaction most likely need to be avoided for life. In contrast, delayed IgG allergies may not be long-term. By identifying the foods that your child is allergic to, strictly avoiding them for three to six months and improving digestive health, your child may lose their allergy to them. In some cases, an IgG allergy reaction is for life, however. 

What Causes Allergy?

Digestive problems are often the underlying factor that leads to the development of delayed food allergies. Many children have excessively ‘leaky’ digestive tracts, which means that partially undigested proteins enter the bloodstream and cause the body to react. So, identifying and avoiding what your child is reacting to is one half of the equation. The other half is improving the health of their digestion.

Frequent use of antibiotics or aspirin, deficiency in essential fats, vitamin A or zinc or a gastrointestinal infection or infestation such as candidiasis are all possible contributors to leaky gut syndrome that need to be corrected to reduce allergy to foods.

A child who has food allergy symptoms such as frequent ear or chest infections is likely to be prescribed antibiotics which may worsen the food allergy, leading to an increase in symptoms and an increase in antibiotics. So, clearly, it’s best to deal with the root cause of the symptoms by identifying food allergens and removing them from your child’s diet rather than relying on antibiotics for short-term relief and long-term worsening of the problem.

In summary, here’s how to test for, and reduce, your child’s allergic potential…

Take wheat and dairy products out of their diet strictly for one month and see how they feel. In any case these food groups are best not eaten frequently.
Improve your child’s digestion by including plenty of fresh fruit, vegetables, seeds and fish in their diet, which contain essential fats and zinc.
Keep antibiotics to a minimum. These damage the digestive tract.
If you suspect your child has a food allergy, have an IgG ELISA food allergy test and see a BANTregistered nutritional therapist. They can both test what your child is allergic to, devise a course of action to reduce their allergic potential and ensure that your child’s diet remains balanced and healthy while excluding these problem foods.