Many eczema patients also suffer from related allergic conditions, such as hay fever, asthma, and food allergy. One theory is that the weakened skin barrier in eczema allows food proteins in the environment to reach immune cells in the skin, sensitizing the patient to certain foods, and potentially leading to food allergy.
In a study published by The Journal of Allergy and Clinical Immunology (JACI), Tsakok and colleagues aim to answer the following questions:
1. Is there a link between eczema and food allergy? In other words, are patients with eczema more likely to have food allergy, and vice versa?
2. Is severe eczema more likely to be linked to food allergy than mild eczema?
3. Is early-onset persistent eczema more likely to be linked to food allergy then eczema that starts later in life and is less persistent?
4. Does eczema arise before food allergy? This would support the notion that eczema may lead to food allergy.
To look at the supporting evidence for these questions, the investigators systematically searched the literature for studies investigating both eczema and food allergy.
66 studies were identified in total. In studies of unselected populations, the likelihood of being sensitized to a food was up to 6 times higher in eczema patients compared to healthy individuals. Similar studies reported that more than half of eczema patients were sensitized to a food (53%), whilst up to 15% demonstrated signs of full-blown food allergy. Studies only including eczema patients reported even higher figures, with two thirds found to be sensitized to a food (66%), and up to 81% confirmed to have true food allergy on testing. 16 studies suggested that severe eczema is more strongly linked to food allergy. 6 studies indicated that eczema of earlier onset or increased persistence is more strongly linked to food allergy. Finally, one study was able to show that eczema arises before food allergy.
This review confirms the close association between eczema, food sensitization and food allergy. This link is stronger with eczema that starts earlier, is more severe and persists for longer. There is also evidence that eczema arises before food allergy, which supports the theory that eczema leads to the development of food allergy.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.
American Academy of Allergy, Asthma & Immunology.