Dr Peter Lio (Northwestern University Chicago, USA) discussed possible food triggers in eczema patients . The role of food allergies is not only an important issue for patients but also for clinicians. Patients are often convinced that food is the main driver of their atopic dermatitis (AD), or parents believe it is a trigger in their children with AD. Studies have shown that there is indeed an increased risk of true food allergy in patients with AD, which is positively correlated to an increasing severity of the disease. Severely affected infants have a nearly 6 times elevated relative risk for an IgE-mediated food allergy . Roughly one third of children with AD have IgE-mediated food allergy . “Many patients believe that food allergy is what is driving their eczema, and that is the part we do not really think bears out in clinical trials,” said Dr Lio. According to his experience, patients perceive adverse reactions to food at a rate 10 times as high as their true prevalence. A trial that Dr Lio stated to be his “favourite study” assessed the relationship between food allergy and AD, both before and after treatment in an established AD population . During an open trial of topical tacrolimus, a decrease in parental food allergy concern during good control of their child’s eczema was observed: 95% of parents felt at the beginning of the trail that food allergy exacerbated their child´s AD. Tacrolimus treatment durations were 3 to 45 months. In this time, parental concern of food allergy decreased significantly (P<0.001). Additionally, estimated food reactions decreased by approximately 80% during 1- and 6-month periods.
Effective therapy – less parental concern
An effective topical therapy was able to significantly reduce the level of concern about food reactions. The authors concluded that successful, stable therapy of AD reduces perceived food reactions and appeases parental fears about food allergy. “Studies have shown that there is a powerful placebo effect in many conditions with dietary change,” said Dr Lio. This might explain the persuasion of many parents that their children´s eczema are triggered by certain food. On the other hand, there is no doubt that eating healthy is a good thing that may have a positive skin effect due to an influence on the microbiome.
Another trial assessed the association of food allergy and AD exacerbations . Analysed were children who had been referred between 2001 and 2011 for one or more suspected food allergies, and who underwent double-blind, placebo-controlled food challenges (DBPCFCs) as part of regular care. A total of 1,186 DBPCFCs were studied. In this trial, sensitisation occurred significantly more often in children with previous AD. However, children with no other symptoms than AD and worsening AD reacted no more often than the placebo group. The authors therefore concluded that children with exacerbation of AD in the absence of other allergic symptoms are unlikely to be food allergic. “We wish foods were the cause for eczema! It would be easier! But we are not that lucky,” concluded Dr Lio.
- Lio P, Lecture F039, AAD Annual Meeting, 1-5 March 2019, Washington DC, USA.
- Hill DJ, Hosking CS. Pediatr Allergy Immunol 2004;15:421-427.
- Thompson MM, Hanifin JM. J Am Acad Dermatol 2005;53 (2 Suppl. 2): S214-219.
- Roerdink EM et al. Ann Allergy Asthma Immunol 2016;116:334-338.