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Chapter: Paediatrics: Gastroenterology and nutrition

Paediatrics: Adverse reactions to food

Food allergy : Defined as an abnormal immunological response to food (incidence is 6–8% in children aged <3yrs).

Adverse reactions to food


Food allergy


Defined as an abnormal immunological response to food (incidence is 6–8% in children aged <3yrs).

   Immediate allergic reactions involve production of food-specific IgE antibodies.


   70% of cases have a family history of atopy.


   Allergy becomes less common as age increases.


   The commonest food allergens are cow’s milk proteins, eggs, peanuts, wheat, soya, fish, shellfish, and tree nuts.




   Diarrhoea +/– blood/mucus.




   Dysphagia, gastro-oesophageal reflux symptoms.


   Abdominal pain.


   Faltering growth (FTT).






   Erythematous rash, particularly peri-oral.


   Asthma symptoms.


   Food induced anaphylaxis.


Food intolerance


Intolerance involves adverse reactions to food that are mediated by non-immunological responses. This condition is more common than food aller-gy. Its presentation is similar to that of food allergy. Fructose intolerance is very common due to usage of high-fructose corn syrup in prepared foods and beverages. Other food intolerances may be due to:

   GI enzyme deficiency, e.g. lactose intolerance, congenital sucrase-isomaltase deficiency.

   Pharmacological reactions to agents contained in food, e.g. caffeine, histamine, tyramine, tartrazine, acetylsalicylic acid.

   Reactions to food toxins or microbes, e.g. haemagglutinins in soy or mycotoxin present in mould-contaminated cereals.


Management of suspected food allergy or intolerance




   Dietary treatment: exclusion of offending food(s) from diet, e.g. milk free, soya free, egg-free diet.

   Involve a paediatric dietitian in the diagnosis and management.

   Extensively hydrolysed or amino acid based milks can be used.

   Dietary exclusion in the mother should be considered if breast feeding.


   Drug treatment: regular therapy may have a role, e.g. oral sodium cromoglicate, corticosteroids, and antihistamines.

IM adrenaline is used by the child or parents for emergency treatment of anaphylactic reactions, particularly if IgE mediated and there are respiratory or systemic symptoms and signs.

After at least 6–12mths of being symptom-free on exclusion diet, consider food challenge if there is a food allergy. If the previous reaction was severe, this should only be done in hospital with full resuscitation facilities available in the event of a serious adverse reaction.




Data are not clear. In newborns with a first degree relative with confirmed food allergy, exclusive breastfeeding to at least age 1yr reduces risk of allergy. If this is not possible then a hydrolysed milk formula can be used. After weaning temporary avoidance of at risk foods may also reduce risk.


Prognosis of food allergy or intolerance


The prognosis depends on the cause. The majority of infantile food allergic reactions resolve by 2yrs. The exception is peanut allergy that tends to persist. Allergies that develop in older children may become chronic.


Lactose intolerance


This is most commonly due to post-viral gastroenteritis lactase deficiency, e.g. rotavirus. Most cases are transient and short lasting (<4–6wks).

In older healthy children and adults, lactase levels commonly decline with subsequent variable severity intolerance (especially in certain populations, e.g. South-east Asian and Afro-Caribbean).

Rarely due to genetic congenital lactase deficiency (primary). Infants present with severe diarrhoea after lactose exposure (present in high quantities in breast milk).


Presentation: diarrhoea; excessive flatus; colic; peri-anal excoriation; stool pH <5.

   Treatment: lactose-free formula milk (soya milk not recommended in children under 6/12).


Cow’s milk protein allergy


   Commonest food allergy in infancy.

   Symptoms depend on where the allergic inflammation is.

   Upper GI tract—vomiting, feeding aversion, pain.

   Small intestine—diarrhoea, abdominal pain, protein-losing

   enteropathy, FTT.

   Large intestine—diarrhoea, acute colitis with blood and mucus in

   stools, rarely, chronic constipation.

   Limited use for RAST or skin testing in infants.

   May occur in breast-fed infants, the reaction is to cow’s milk protein secreted into breast milk following maternal ingestion. Usually presents as allergic colitis in an otherwise healthy happy infant.

   In infants, first treat by limiting cow’s milk protein intake (and commonly soy protein):


   In exclusively breast-fed infants, this is achieved by a maternal exclusion diet to these proteins.

   In formula fed infants feed with a hydrolysed formula (short peptides).

   If symptoms severe, or unresponsive to hydrolysed formula, then an elemental (amino acid) formula may be required.

   Anti-inflammatory medications are very rarely needed.

   Avoid using goat’s or sheep’s milk as a cow’s milk substitute, as 25% will also develop allergy to these milks (cross-reactivity). Similar cross-reactivity also often occurs with soya milk. Use of soya milk is not recommended under age 6mths.

   After weaning, introduce a cow’s milk protein free diet (supplement with oral calcium if required).

   Consider a cow’s milk protein challenge after 6–12mths.


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