Diet and Atopic Dermatitis

Prevention of AD Through Dietary Modification

The National Institute of Allergy and Infectious Diseases consensus group published guidelines on food allergies that affect AD management, including avoidance of proven allergens but not random elimination of food allergens in AD; the group identifies AD and family history of AD as risk factors for food allergies.¹⁶ The best data in support of avoidance of documented food allergens to reduce AD severity has been found for egg white allergy and avoidance. Active egg allergy also is linked to staphylococcal superantigen IgE sensitizations,¹⁷ but the reason for the link is not yet clear. For the pediatric population, exclusive breastfeeding until 4 to 6 months of age and introduction of solids within the first 4 to 6 months as well as avoidance of maternal dietary restriction during pregnancy and lactation was further endorsed, with use of hydrolyzed formulas as an alternative to exclusive breastfeeding in infants who are not exclusively breastfed (cost permitting).^16,18

A Cochrane review of maternal dietary restrictions during pregnancy found no benefit of maternal prenatal dietary restriction on AD prevalence in the first 18 months of life but did note an association with lower mean gestational weight.¹⁹

There is currently an effort to produce foods, such as soybeans and corn, that are genetically modified to reduce exposure to the allergenic component, but it is possible that when large-scale challenges occur, these foods also will be allergenic.^20,21 In the case of a modified apple, some promising reduction in allergy symptoms has been reported.²² Although genetically modified foods may benefit children with food allergies in the future, they are a source of some controversy.

Complementary and Alternative Medicine

The AAD guidelines do not recommend complementary and alternative medicine (CAM) to treat AD,¹⁴ but it remains a commonly used therapy in the United States. A 2014 analysis of data from the 2007 US-based national health interview survey of 9417 children (age range, 0–17 years) demonstrated that 46.9% of children used 1 or more CAM, of which 0.99% used CAM specifically for AD. In this study, herbal therapy, vitamins, homeopathy, diet, and movement techniques were associated with increased prevalence of AD.²³ Although some herbals have been shown to be beneficial in AD,²⁴ hepatotoxicity has been reported with some herbal therapies.²⁵ Complementary techniques with evidence-based support include massage therapy,²⁶ relocation to an alternative climate, acupuncture that rivals cetirizine in efficacy, and supportive nutritional advice.^24,27

Factors Affecting the Incidence of AD

Atopic dermatitis is of greater prevalence in children in developed wealthy nations such as the United States, supporting the role of enhanced hygiene and overall good health through vaccination as a possible contributor to the rise in AD prevalence in the last 4 decades.^28,29 Alternatively, viruses such as respiratory syncytial virus may trigger AD, suggesting vaccination against the virus may reduce the risk for AD.³⁰ Overall, vaccination improves life expectancy and should be conducted on schedule without reservation. Other aspects of hygiene that could conceptually affect prevalence of AD are raw food ingestion and the effects of foodborne microbes on the intestinal microbiome in relationship to AD development. Probiotics have been tested for this purpose.

Probiotics and prebiotics have been theorized to work through a reduction in inflammation; these agents have some evidence in their favor, but they were not endorsed in the AAD guidelines¹⁴ despite showing promise in meta-analysis. In particular prenatal and postnatal (maternal and child) supplementation of Lactobacillus rhamnosus shows promise.^31-33 Food elimination diets and supplements including vitamin D, selenium, fish oil, borage oil, and zinc were not found to be beneficial and were not recommended in the AAD guidelines.^14,34

Percutaneous exposure to peanuts, possibly in household dust, may be the mechanism of peanut sensitization in AD²⁷ via an inherent adjuvant effect of peanut protein.²⁸ The recent LEAP (Learning Early About Peanut Allergy) trial randomized 530 infants aged 4 to 11 months to peanut-avoidant versus peanut-exposed diets for 60 months. The results showed statistically reduced (approximately one-twelfth of the risk) peanut allergy even in infants known to be sensitized (approximately one-third of the risk).³⁵ It is now recommended in countries with a high prevalence of peanut allergies to introduce peanuts to an infant’s diet between 4 and 11 months of age (evidence level 1 [highest level of evidence]), with referral to an allergist for introduction in known sensitization cases and severe AD.³⁶ In the setting of known or documented peanut allergy and for evaluation of potential food allergies, an allergist should be consulted.

Other interventions have been described as promising in mouse models. Those supplements include Lithospermum erythrorhizon,³⁷Platycodon grandiflorus,³⁸Hypsizygus marmoreous,³⁹ fortified ginseng extract,⁴⁰ polyunsaturated fatty acids,⁴¹ and galactooligosaccharide.⁴² Prebiotic oligosaccharides also are promising for early prevention of AD symptoms in infants, but otherwise these agents have remained largely untested in AD.⁴³ None of these therapies have been endorsed by the AAD, and the long-term safety and efficacy in humans remains to be proven.