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Food Allergies and EczemaSabrina Santiago, MD

Abstract

Eczema is one of the most common

skin conditions of childhood. Patients

with eczema suffer in a chronic cycle

of itch, scratch, and inflammation. For

children with severe eczema, constant

itching and scratching can have many

consequences including skin infections,

behavioral issues, and sleep problems.

Parents often find themselves searching

for a trigger for their child’s eczema flare,

and after they have switched detergents,

applied a thick moisturizer and topical

steroids, and removed all wool clothing

from their child’s wardrobe, they wonder,

“Could food allergies be playing a role?”

[Pediatr Ann. 2015;44(7):265-267.]

The answer to this question is controversial, and as we learn more about the pathophysi-

ology of allergies, we come up with more questions than answers. How much can I trust skin prick testing and serum immunoglobulin E (IgE) lev-els? When do I advise switching from

cow’s milk-based formula to elemen-tal formula? When do I recommend a food elimination diet? The prevalence of food allergies in children with ec-zema is estimated to be between 33% and 63%.1 In this article, we review common food allergens (Figure 1) that cause eczema, examine the role of

Sabrina Santiago, MD, is a Primary Care Pe-

diatrician, University of California San Francisco,

Benioff Children’s Hospital; and an Assistant Pro-

fessor of Pediatrics, Department of Pediatrics,

University of California San Francisco.

Address correspondence to Sabrina Santiago,

MD, via email: sabrina.santiago@ucsf.edu.

Disclosure: The author has no relevant finan-

cial relationships to disclose.

doi: 10.3928/00904481-20150710-04

Figure 1. A toddler eating wheat bread.

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allergy testing, and discuss the utility of elimination diets.

Identifying eczema triggers can be difficult, in part, because the time course for allergic response varies. The most dramatic and obvious pre-sentation is the type 1 IgE-mediated reaction, in which a patient experi-ences hives, angioedema, and wheez-ing almost immediately after inges-tion of the offending food. However, there are more subtle presentations of food allergy, such as pruritus that oc-curs soon after ingestion, or eczema flares that appear 6 to 48 hours after ingestion of the food.2 Additionally, the natural course of eczema is to wax and wane, and it is hard for parents to be sure that their child’s eczema flared in response to a specific food, or if it would have flared regardless.

COMMON FOOD ALLERGENSFood allergens appear to play

a more significant role in children younger than age 2 years, and in chil-dren with severe eczema.3 The most common food allergies are milk, eggs, soy, wheat, peanuts, tree nuts, fish, and shellfish. Infants have the most trouble from cow’s milk, eggs, wheat, and soy. In toddlers and school-aged children, nuts, fish, and shellfish are added to the list.

Some food allergies are more likely to abate as a child ages. For example, 80% of children with cow’s milk aller-gy will outgrow it by the time they are age 5 years.4 Similar findings are seen in children with egg, soy, and wheat allergies. On the other hand, only 20% of patients with tree nut allergy will “grow out” of their allergy.4

For infants, eczema (Figure 2) may not be the only manifestation of food allergy, and babies may exhibit gastro-intestinal symptoms, failure to thrive, irritability, and sleep disturbance. For

children who are breast-fed, eczema may flare in response to allergens in the mother’s diet. Studies of maternal dietary restriction in pregnancy do not show an effect on future development of atopic disease in the child. Stud-ies of maternal dietary restriction for nursing mothers do not support re-striction in atopic disease, with the exception of atopic dermatitis.5 When maternal dietary restriction is con-sidered, one must do so carefully, to ensure adequate nutrition of the moth-er. It is worth saying that exclusive breast-feeding is recommended in the first 6 months of age by the American Academy of Pediatrics and in the first 4 to 6 months by the National Institute of Allergy and Infectious Diseases (NIAID).6 There is even some evi-dence that for infants at high risk for atopy, exclusive breast-feeding for at least 4 months decreases cumulative incidence of atopic dermatitis, cow’s milk allergy, and wheezing in early childhood.7

For babies who are formula fed, changing from a standard cow’s milk-based formula to a hydrolyzed formula may be an important part of treatment of atopic dermatitis. Additionally, for babies who are not exclusively breast-fed, parents can consider giving hy-drolyzed formulas instead of intact cow’s milk-based formula to prevent or delay atopic disease in children at risk for food allergy. “At risk” is de-fined as having a biologic parent or sibling with existing or a history of al-lergic rhinitis, asthma, atopic derma-titis, or food allergy.7 Unfortunately, the cost of hydrolyzed formula may be prohibitive for some families.

Another important NIAID guide-line suggests that one should not delay introduction of potentially allergenic foods beyond ages 4 to 6 months, even in infants at risk of developing allergic

disease.7 The rationale is that little ev-idence exists to show that this practice prevents atopic disease.

FOOD ALLERGY TESTINGBefore undertaking food allergy

testing, the provider must explain that the tests are imperfect. The gold stan-dard is oral food challenges, which are conducted under direct supervi-sion with a medical provider, who is prepared for serious allergic reactions. Unfortunately, oral food challenges can be time-intensive and usually re-quire referral to an allergist. More common testing methods include se-rum IgE levels and skin prick testing. These tests, unfortunately, can be ex-tremely confusing to interpret. Each food has its own positive and negative predictive value, and serum IgE lev-els are considered positive at different thresholds. For example, a serum IgE level of 3 kU/L may be considered positive for egg allergy in a 1-year-old, but negative for cow’s milk in an older child, yet it is the same absolute value.

Additionally, skin prick testing and serum IgE levels do not always cor-relate with clinical symptoms. Most allergy specialists recommend against blanket testing for all food allergies, because the positive predictive accu-racy is approximately 50% depending on the food.4 One study estimates that 10% of children with food allergies may have false-negative testing.1 In-stead, testing should be directed, and used to confirm suspicion of food al-lergy based on the child’s history.

ELIMINATION DIETSAlthough there are common food

allergies including cow’s milk, eggs, soy, wheat, and shellfish, there is no uniformly recommended diet for chil-dren with eczema or nursing mothers

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of infants with eczema. An elimination diet should only be considered when a true food allergy has been diagnosed, either by specific IgE assay, skin prick testing, by atopy patch testing, or oral food challenge. For infants and chil-dren with severe eczema and a con-firmed food allergy, elimination diets will likely be part of the treatment. However, in a child with mild eczema, the risks and benefits of elimination diets must be considered. The main risk is nutritional deficiency. If you eliminate cow’s milk, for example, another calcium source should replace it. If an elimination diet is undertaken, experts recommend elimination of the specific food for 4 weeks.1 If the elimination diet is successful, one can reintroduce the food for 2 days, and see if the child’s eczema flares again.

CONCLUDING REMARKSChildhood eczema can be truly de-

bilitating, resulting in poor sleep, be-havioral issues, skin infections, and frequent doctor visits. Food allergies seem to play a key role in eczema flares, especially in those children with moderate-to-severe disease. Al-though there are many questions still to be answered, this article provides many good tips to pediatric primary care pediatricians about how to ap-proach diagnosis and management of food allergies and eczema (Table 1).

REFERENCES 1. Rancé F. Food allergy in children suffering

from atopic eczema. Pediatr Allergy Immunol. 2008;19(3):279-284.

2. Werfel T, Breuer K. Role of food allergy in atopic dermatitis. Curr Opin Allergy Clin Im-munol. 2004;4(5):379-385.

3. Fiocchi A, Bouygue GR, Martelli A, Ter-

racciano L, Sarratud T. Dietary treatment of childhood atopic eczema/dermatitis syndrome (AEDS). Allergy. 2004;59(Suppl 78):78-85.

4. Forbes LR, Saltzman RW, Spergel JM. Food allergies and atopic dermatitis: differentiating myth from reality. Pediatr Ann. 2009;38(2):84-90.

5. Kramer MS, Kakuma R. Maternal dietary antigen avoidance during pregnancy and/or lactation for preventing or treating atopic dis-ease in the child. Cochrane Database Syst Rev. 2006;19(3):CD000133.

6. NIAID-Sponsored Expert Panel, Boyce JA, Assa’ad A, Burks AW, et al. Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-spon-sored expert panel. J Allergy Clin Immunol. 2010;126(suppl 6):S1-58.

7. Greer FR, Sicherer SH, Burks AW; American Academy of Pediatrics Committee on Nutri-tion; American Academy of Pediatrics Section on Allergy and Immunology. Effects of early nutritional interventions on the development of atopic disease in infants and children: the role of maternal dietary restriction, breastfeed-ing, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics. 2008;121(1):183-191.

Figure 2. An infant with eczema covering the face.

TABLE 1.

Take-Home Points• Exclusive breast-feeding is still recommended until age 4 to 6 months, and may prevent atopic

disease in early childhood

• For babies who are not exclusively breast-fed, and are at risk for atopic disease, parents can

consider giving their child a hydrolyzed formula rather than an intact cow’s milk-based protein

formula

• Consider referral to an allergist in young children (younger than age 2 years) with moderate-

to-severe eczema, especially those that have multiple symptoms, including gastrointestinal

symptoms, failure to thrive, and sleep disturbance

• Tailor your food allergy testing according to the patient’s history instead of blanket testing,

which helps to avoid false-positive results

• Food elimination diets should be carefully weighed against ensuring adequate nutrition for

the child. If undertaken, the offending food may be removed from the diet for 4 weeks, and

re-introduced for 2 days. Food allergy is suspected if the child’s eczema improves over the 4

weeks and flares with reintroduction

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