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Clinical: Spotting food allergies in children

Key learning points

  • Children with one allergic disease or a family history of allergies are at a higher risk of developing further allergies
  • Children suffering from eczema are more likely to develop food allergies
  • The majority of children with cow’s milk and egg allergy are able to tolerate these food groups by the time they reach school age

Allergy is the most frequent chronic disease in children.[1] Allergic conditions often begin in childhood and can persist for many years, often for life. However, they can also can develop at any age.

Allergy can range from very mild to very severe symptoms that impact on quality of life. In some cases, the symptoms can be life threatening and require immediate medical intervention – for example, in the case of anaphylaxis, for which the first-line treatment is adrenaline if the child is to survive.

Children with one allergic disease, eg eczema, have a high risk of developing further allergies such as food allergy. Allergies are often hereditary, so when a child is born to parents who have an existing allergic condition such as asthma, eczema, hay fever or a food allergy, there is an increased likelihood that the child will develop an allergic condition (the tendency to this is called ‘atopy’). However, new cases arise without any family history, which is leading to an increase of research into environmental trigger factors such as the microbiome, weaning guidelines and air quality from allergenic pollens that are being potentiated by air pollutants.

Recognising symptoms

Children with asthma as well as a food allergy are at an increased risk of suffering a more severe form of allergic reaction – especially if the asthma is not well controlled or the child or carer do not understand the potential dangers, signs and symptoms. It is crucial that they are able to recognise symptoms and manage an acute attack and, most importantly, get timely medical intervention via emergency services. Education of the child or carer as well as a clear written management plan are vital. Many of these children will also have an adrenaline auto-injector, so training in its use must be given on initial prescription as well as regular updates. 

There is an increasing prevalence of food allergy in young children. It is probably one of the most worrying forms of allergic disease in children, although not all parents or primary care professionals are able to recognise the symptoms, unless they are severe, in which case they are often taken to A&E, treated and discharged without follow-up or referral. The danger in this approach is that the patient does not receive the appropriate diagnosis, risk assessment, treatment and management advice, so they remain vulnerable. Severe life-threatening reactions are rare in young children and often tend to be more of a problem among teenagers and young adults, and can unfortunately result in death. 

Teenagers are a challenging group because of multifactorial influences including peer pressure, alcohol, experimentation, relationships, increased independence and being away from home, and issues with eating out. There is also now mounting evidence to suggest that allergic children are more likely to be bullied – and that sometimes the bully uses the allergen the patient has to avoid, adding to the general level of anxiety and stress.[2]

Common food allergies

More than 90% of food allergy in children is caused by just eight core foods,[3] which include: 

  •  Cow’s milk.
  •  Soy.
  •  Hen’s eggs.
  •  Peanuts.
  •  Tree nuts (including walnut, almond, hazelnut, cashew, pistachio, and Brazil nuts).
  •  Wheat.
  •  Fish.
  •  Shellfish (crustaceans such as prawns and lobsters, and molluscs, such as mussels and squid).

Food labelling legislation came into force in December 2014, endorsed by the Food Standards Agency (FSA), with a requirement that the top 14 food allergens are clearly labelled on packaging. Other than the eight core foods, these include:

  •  Mustard.
  •  Celery.
  •  Sesame.
  •  Sulphites.
  •  Gluten-containing grains.
  •  Lupin (many people with peanut allergy have severe reactions to lupin due to its cross-reactivity).

Egg is a common allergen in children and is usually identified in the first year of life, when egg is introduced into the diet. Some children are able to tolerate baked egg (for example, in a cake) but not in looser forms, such as scrambled. This is because the heating process changes the way the immune system recognises it.

The majority of children with cow’s milk and egg allergy are able to tolerate these food groups by the time they reach school age. However, careful exclusion and management needs to be overseen by a dietitian, as in the UK, both milk and egg play a big part of the nutritional requirements of most children. We are, however, also seeing IgE mediated cow’s milk allergy and egg allergy being a persistent rather than a transient disease. For these cohorts, new therapies only available in some specialist allergy services are being used, mostly under trial-type conditions. This is a treatment called immunotherapy. It is used to change the allergic immunological pathway. Although it is a very new concept for food allergy, it has been highly successful in pollen and venom allergy. New European guidelines on immunotherapy are due to be published later this year and will have a section for primary care. 

Allergies to peanuts and tree nuts tend to persist and the likelihood of growing out of them is reduced. Peanut allergy has been much researched and studies such as Learn Early About Peanut (LEAP)[4] inform us that there is now scientific evidence that healthcare providers should recommend introducing peanut-containing products, such as smooth peanut butter (never whole peanuts under five years of age) into the diet of ‘high-risk’ infants early on in life (of between four to 11 months of age). This is being trialed in countries where peanut allergy is prevalent, since delaying the introduction of peanuts may be associated with an increased risk of developing peanut allergy.

Infants with early-onset atopic disease, such as severe eczema or egg allergy in the first four to six months of life, may benefit from evaluation by an allergist or physician trained in the management of allergic diseases in this age group. This is to help diagnose any food allergy and assist in implementing these suggestions about the appropriateness of early peanut introduction.[5]

The LEAP study results have helped to fine-tune these recommendations for peanuts. LEAP convincingly showed that not only was there strong evidence that peanut introduction between four and 11 months of life was protective for the development of peanut allergy, it also highlighted that a delay in peanut introduction was associated with harm and a significantly increased risk for allergy. Early peanut introduction was associated with an 86% risk reduction among children with no baseline positive peanut skin test and a 70% risk reduction among those with small positive baseline peanut allergy skin tests.[6]

Another study, Enquiring about Tolerance (EAT), investigated when the best time was to introduce allergenic foods into the infant diet in order to minimise the risk of development of later allergic disease, including food allergy. The EAT study showed that the impaired skin barrier can lead to food allergy sensitisation. So applying the LEAP intervention to a normal population, 15% of babies and infants have eczema.[7,8] The findings showed that if eczema had been severe and present for more than six months in a baby, there was an increased risk of 40% of developing a peanut allergy.[9]

Research

Dual allergen exposure hypothesis for the pathogenesis of food allergy shows that if a child experiences cutaneous exposure through an impaired skin barrier before they have developed oral tolerance via weaning, they are more likely to develop sensitisation to foods that are used commonly around the home, such as egg or peanuts. The longer the eczema is not managed correctly, the more likely the individual is to contract multiple food allergies. 

Both of these studies have: 

  •  Been instrumental in the way feeding guidelines will be addressed in the future.
  •  Highlighted the benefits of early introduction of allergenic foods.
  •  Advised the importance of keeping the food in the diet for sustained oral tolerance.
  • At present, the existing guidance in the UK recommends weaning when the baby is developmentally ready, which is around six months.

The National institute for Health and Clinical Excellence (NICE) launched a set of quality standards in March 2016 [10] that gives guidance on diagnosis, assessment and management of food allergy, recommending that:

  1. Children and young people with suspected food allergy have an allergy-focused clinical history taken.
  2. Children and young people whose clinical history suggests an IgE mediated food allergy, are offered skin-prick test or blood tests for IgE antibodies to the suspected allergens and likely co-allergens.
  3. Children and young people whose allergy-focused clinical history suggests a non-IgE mediated food allergy, and who have not had a severe delayed reaction are offered a trial elimination of the suspected allergen and subsequent reintroduction. 
  4. Children and young people are referred to secondary or specialist allergy care when indicated.

Research also shows there is:

  •  A high incidence of self-reported allergy.
  •  A lack of knowledge of the difference between food allergy and intolerance.[11] A common misconception is between lactose intolerance and cow’s milk protein allergy (CMPA). Lactose is the milk sugar, and a lactose-free formula is required for cases of lactose intolerance where breast milk is not used. In CMPA the culprit is the protein, so breastfeeding mothers have to take milk from animals (such as cow or goat) out of their diet if the child is reacting through breast milk. If the child is formula fed, an extensively hydrolysed or amino acid formula is required by prescription. Milk allergy in primary care (MAP) guidelines can help.

Conclusion

Genetics and heritability patterns influence who may develop allergic disease, so nurses should always ask about family history of allergies.The Fillagrin gene has a key role in the epidermal barrier and atopic eczema. Nurses should assess the child or infant for eczema and treat promptly. 

It is important to educate the child or carer about the importance of daily or frequent emollient use, in between treatment of any acute exacerbations, to prevent skin becoming dry, cracked and itchy. There is a very strong association between eczema and food allergy. Studies suggest that 80% of food allergy is preceded by eczema [11] (the main culprits are egg, milk and peanut). Therefore, knowledge of the patient’s clinical history is important. Sensitisation to foods occurs through the leaky skin barrier (cracked, weepy, itchy eczema comes under this category).

Other allergens, such as pollens, can cause sensitisation through inflamed nasal and lung mucosae, which is why eczema, allergic rhinitis and asthma must be controlled. Prevention and control are the cost-efficient way to decrease the disease burden.

References

1 Muraro A et al. Food allergy and Anaphylaxis. European academy of allergy and clinical immunology (EAACI) publication. Allergy 2014;69:1008-25. doi: 10.1111/all.12429. Epub 2014 Jun 9 

2 Lieberman J, Weiss C, Furlong T. Bullying Among paediatric patients with food allergy. Ann Allergy Asthma Immunol 2010;105:282-6.

3 Hefle SL, Nordlee JA, Taylor SL. Allergenic foods. Critical Reviews in Food Science and Nutrition 1996;36:S69-89.  

4 Du Toit G, Lack G, Roberts G et al. Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy. N Engl J Med 2015;372:803-13.

5 Fleischer et al. Consensus communication on early peanut introduction and the prevention of peanut allergy in high-risk infants. World Allergy Organization Journal 2015;8:27 DOI 10.1186/s40413-015-0076-x

6 Greenhawt M. New Guideline for Prevention of Peanut Allergy: Where We Stand Now in Preventing Food Allergies. USA online article from Medscape 5.1.2017

7 Flohr C, Mann J. New insights into the epidemiology of childhood atopic dermatitis. Allergy 2014;69:3-16 

8 House of Commons. Health Committee. Written evidence from the British Association of Dermatologists (LTC 89). May, 2013. 

9 Perkin MR, Logan K, Marrs T et al. Enquiring About Tolerance (EAT) study: feasibility of an early allergenic food introduction regimen. The Journal of Allergy and Clinical Immunology 2016;137:1477-86.e8. doi:10.1016/j.jaci.2015.12.1322.

10 National Institute for Clinical Excellence. Quality standard for food allergy (QS118)  March 2016

11 Lozinsky AC, Meyer R, Anagnostou K et al. Cow’s Milk Protein Allergy from Diagnosis to Management: A Very Different Journey for General Practitioners and Parents. Children 2015;2:317-29.

Further reading

Hill DJ, Heine RG et al. IgE Food Sensitization in Infants with Eczema Attending
a Dermatology Department. The Journal of Paediatrics 2007;151:359-63.