Atopic dermatitis (eczema) and food allergies are fairly common worldwide. In some people, eczema is exacerbated by food allergies, and in other cases, eczema is considered to be the cause of the food allergy. Here, we explore this bi-directional relationship.
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Eczema precedes food allergies
Eczema is a common inflammatory skin condition that affects almost one in five children and one in twenty adults. Interestingly, around 30% of children and 81% of all people with eczema also have a food allergy. Given that the prevalence of food allergies in children in the general population is around 3-6% and in adults is 6%, the elevated rate of food allergies in those with eczema suggests that the conditions are linked.
For many years, scientists and medical professionals have recognized the connection between allergies and atopic diseases; however, data that supports this connection and explains the nature of the relationships has only emerged in recent years. Now, it is believed that eczema seems to trigger food allergies somehow.
A recent study published in The Lancet found that eczema of increased severity and chronicity is linked with food allergies, and the skin condition appears to precede the emergence of the allergy. It seems that the development of eczema triggers the formation of food allergies.
Other studies have demonstrated a development pattern, starting with eczema, leading to food allergies, food allergies, and asthma.
Molecular differences may underlie the relationship
Recently, scientists have discovered that children suffering from eczema and a food allergy have molecular differences in the top layers of the skin. These molecular differences have not been observed in those with eczema alone, suggesting that these differences may predispose a person to develop a food allergy.
While areas of skin that become inflamed due to eczema are indistinguishable between children with eczema and food allergies and those with eczema alone, differences in structure and molecular composition are found in the non-lesional skin. Scientists have further defined these differences to get one step closer to identifying children at risk of developing food allergies to help establish preventative measures. They determined that the skin of children with eczema and food allergies was more prone to water loss and had an abundance of Staphylococcus aureus, a species of bacteria, as well as a gene expression reflective of an immature skin barrier. Research has shown that these skin abnormalities extend beyond the visible lesions caused by eczema and are unique to children who also suffer allergies, suggesting that these abnormalities may play a role in the development of food allergies.
Food and diet can exacerbate eczema
While much research has highlighted the likeliness that eczema may precede food allergies and be part of a greater pathway, including the development of respiratory conditions such as asthma, there is also evidence to show that in some cases, food allergies can be the cause of eczema. Research has found that certain foods can exacerbate eczema or cause it due to systemic contact dermatitis.
Certain foods can trigger immediate reactions that worsen eczema due to pruritus and the related itching and scratching for some people with eczema. Back in 1936, this link was demonstrated in Engman’s description of a child with eczema whose symptoms worsened after eating wheat. On beginning a wheat-free diet, the child’s symptoms improved, and on recommencing the consumption of wheat foods, the child’s symptoms again worsened. This research established that avoiding trigger foods could help to manage symptoms of eczema in some cases.
It is believed that in cases where food causes immediate skin reactions, immunoglobulin E-mediated hypersensitivity reactions have been triggered. Immediate reactions occur several minutes to a few hours after exposure to the problem food. In some cases, late eczematous reactions may occur up to two days later; these instances are known as “food responsive eczema”. The prevalence of this type of reaction is not known, partly due to the delayed nature of the response, which may veil the association between the food and the skin response.
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More research is needed to understand the food-skin connection fully
Evidence collected over many decades has uncovered a strong relationship between food allergies and dermatological disorders. It seems that eczema often precedes the development of food allergies and that molecular differences in the outer layer of the skin may be responsible, at least in part, for this link.
Additionally, food allergies are known to exacerbate skin conditions such as eczema, although it is possible, even probable, that this happens via a distinct mechanism. Overall, more research is needed to understand the relationship between food allergies and dermatological disorders to establish effective preventative measures and new therapies to treat both conditions.
- Leung, D., Calatroni, A., Zaramela, L., LeBeau, P., Dyjack, N., Brar, K., David, G., Johnson, K., Leung, S., Ramirez-Gama, M., Liang, B., Rios, C., Montgomery, M., Richers, B., Hall, C., Norquest, K., Jung, J., Bronova, I., Kreimer, S., Conover Talbot, C., Crumrine, D., Cole, R., Elias, P., Zengler, K., Seibold, M., Berdyshev, E. and Goleva, E., 2019. The non-lesional skin surface distinguishes atopic dermatitis with food allergy as a unique endotype. Science Translational Medicine, 11(480). https://www.science.org/doi/10.1126/scitranslmed.aav2685
- Sweeney, A., Sampath, V. and Nadeau, K., 2021. Early intervention of atopic dermatitis as a preventive strategy for progression of food allergy. Allergy, Asthma & Clinical Immunology, 17(1). aacijournal.biomedcentral.com/articles/10.1186/s13223-021-00531-8
- Tsakok, T., Marrs, T., Mohsin, M., Baron, S., du Toit, G., Till, S. and Flohr, C., 2017. Does atopic dermatitis cause food allergy? A systematic review. The Lancet, 389, p.S95. www.thelancet.com/.../fulltext