The link between eczema and food allergies

What is eczema?

Eczema, also known as atopic dermatitis, is characterised by an itchy, red, skin rash. (1) It is a complex allergic disorder with no quick or easy cure, and current available treatments are generally topical and not always effective. Eczema can significantly impact the quality of life of the afflicted, and also those closest to them. (1) This uncomfortable disorder can cause disrupted sleep, reduced concentration and even behavioural difficulties. (1)

Food Allergies

The development of a food allergy is multifactorial and complex. (2) The prevalence of food allergies has increased drastically over the recent decades, presenting a significant public health burden. (2) Australia has the highest prevalence of food allergies in the world, with approximately 10% of infants allergic to one or more foods. This is in comparison to only 1-5% in other developed countries. (2) The most common allergens are cow’s milk, eggs, soy, wheat, fish, peanuts and shellfish and the only proven treatment so far is elimination from the diet. (3)

The link between eczema and food allergy

Eczema is very commonly associated with food allergies. Approximately one in five infants with eczema ends up developing a food allergy, and the more severe the eczema, the higher the likelihood of a food allergy arising. (2) Approximately half of the children with severe early onset eczema in the first three months of life will develop a food allergy by the age of one. (2) One accepted hypothesis for this link between eczema and food allergy is known as the ‘Dual Allergen Exposure Hypothesis’. This hypothesis proposes that infants with eczema experience low-dose allergen exposure through their disrupted skin barrier (cutaneously), which triggers sensitisation. (2) If the child is given the allergen orally early on in life (i.e. around six months), oral tolerance is more likely to occur. If the allergen is avoided orally, food allergy can develop. (2)

Reducing the risk of developing eczema and food allergy  

Eczema and food allergies both lie under the umbrella term ‘atopic diseases’, which are chronic inflammatory disorders that arise in predisposed people whose immune system treats common environmental antigens as threats. (4) Whilst genetic factors clearly influence the development of atopy, there are many modifiable environmental factors that may also affect the risk of development. (5)

Maternal Diet and breastfeeding

The first potential influence on a child’s risk of developing atopy occurs through the maternal diet in pregnancy. (5) Studies have shown that maternal diets most closely resembling the Mediterranean diet, which is rich in fruits and vegetables, fish, and foods containing vitamin D, lowered the risk for atopy in their children. (5) There is also evidence that excluding allergens from the maternal diet during pregnancy or breastfeeding does not offer a protective effect against the development of atopic disease in the infant, and a maternal exclusion diet is therefore not recommended. (5) Breastfeeding exclusively for at least three to four months has also been shown to decrease the cumulative incidence of eczema in the first two years of life, with or without any further breastfeeding after four months. (5)

Introducing Allergenic Foods - The timing of the introduction of allergenic foods into the diet is also very important, especially if there is pre-existing eczema, for the potential development of food allergies. There is now strong evidence to suggest that introducing allergenic foods in the first year of life will not increase the risk of developing food allergies or eczema,  and may even prevent peanut allergy. (6) Prior to 2008 it was recommended that high-risk infants should delay the introduction of highly allergenic foods, but new evidence has proven this to be incorrect, showing that this delay may even provoke potential food allergies. (2) In 2008 the Australasian Society of Clinical Immunology and Allergy introduced new recommendations for peanut introduction, stating that infants with mild-to-moderate eczema should introduce peanut-containing foods at around 6 months to lower their risk of developing a peanut allergy. (2, 5)

Gut Health and Atopy

The gut microbiome is increasingly implicated in many modern-day diseases, and eczema and food allergies are no exception. Studies have shown that a lack of exposure to microbes and infections in early childhood may increase susceptibility to allergic disease because of the effect that this has on the microbiome, and subsequently, the immune system. (2) There is still a lot to be learnt about the role of the gut, but numerous studies support the idea that food allergies are associated with changes in microbial composition. (2) Children with eczema have a different microbial composition, with higher rates of Clostridium and lower levels of Lactobacilli and Bifidobacterium, than their non-allergic peers. (3) Numerous studies have shown that probiotic supplementation, particularly with lactobacillus rhamnosus (LGG), can reduce the risk of eczema. (2) Less is known about the link between probiotic use and the prevention of food allergies, but, as discussed in the ‘Dual Allergen Exposure Hypothesis’, preventing eczema occurring in the first place may reduce the likelihood of developing a food allergy because the intact skin barrier offers protection against potential allergens entering cutaneously. (2)

References

1. Harnik E, Aston A. FOOD ALLERGY IN PAEDIATRIC ECZEMA. Dermatological Nursing. 2018;17(3):26-9.

2. Peters RL, Neeland MR, Allen KJ. Primary Prevention of Food Allergy. Current allergy and asthma reports. 2017;17(8):52.

3. Berni Canani R, Di Costanzo M, Pezzella V, Cosenza L, Granata V, Terrin G, et al. The Potential Therapeutic Efficacy of Lactobacillus GG in Children with Food Allergies. Pharmaceuticals. 2012;5(6):655-64.

4. Scadding G. Atopic Allergy. Encyclopedia of Immunology. 1998:251 - 5.

5. Greer FR, Sicherer SH, Burks AW. The Effects of Early Nutritional Interventions on the Development of Atopic Disease in Infants and Children: The Role of Maternal Dietary Restriction, Breastfeeding, Hydrolyzed Formulas, and Timing of Introduction of Allergenic Complementary Foods. Pediatrics. 2019;143(4):1-11.

6. Obbagy JE, English LK, Wong YP, et al. Complementary feeding and food allergy, atopic dermatitis/eczema, asthma, and allergic rhinitis: a systematic review. Am J Clin Nutr. 2019;109(Suppl_7):890S-934S. doi:10.1093/ajcn/nqy220

Written By Brittany Darling

NUTRITIONIST (BHSC), WESTERN HERBAL MEDICINE (ADV DIP),

CERT. PAEDIATRIC NUTRITION