Elimination Diets for Atopic Dermatitis: Are They Effective?

The onset and progression of atopic dermatitis (AD) are influenced by a range of environmental, pharmacologic, psychological, hereditary, and nutritional factors.¹ In a number of recent studies, researchers have focused on elucidating the role of diet and dietary restriction(s) on the management and progression of AD.^2-4

A general perception that milk and dairy products exacerbate the symptoms of common skin conditions such as acne and AD often prompts patients with these conditions to go on elimination diets. While some patients report symptom improvement, medical professionals warn that the benefits of restrictive diets are often not scientifically validated.⁵ If patients go too far in restricting their diets, serious medical problems can develop, including vitamin deficiencies, undernutrition, and related complications.^6,7

Do certain foods exacerbate the symptoms of AD? Are elimination diets safe and effective? Can dietary supplements alleviate some of the bothersome symptoms of AD?

Dermatology Advisor looked for answers to these questions in an interview with Peter Lio, MD, clinical assistant professor of dermatology and pediatrics at Northwestern University Feinberg School of Medicine in Chicago, Illinois, and Rajani Katta, MD, clinical assistant professor of medicine at Baylor College of Medicine in Houston, Texas.  

Dermatology Advisor: Does clinical research evidence support the use of dietary restrictions for management of AD?

Peter Lio, MD: After a thorough review of the literature, it seems that restriction diets are generally not helpful for AD in unselected patients. This means that in the absence of a specific known allergy (such as egg or dairy), simply avoiding foods does not seem to reliably help. There is no doubt that if a true food allergy exists, it can be one of the triggers for a flare-up, but sometimes patients get confused about this. By all means, everyone should strictly avoid foods that they are known to be allergic to.

However, it is also important to reinforce that there are patients who swear by the fact that a dietary change has helped them. My intention is not to say that they are “wrong” here, as there is a wide range of experiences and, even in the studies that show no benefit overall, there are certainly some patients who seem to benefit. However, in general, dietary restrictions are not helpful for most patients.

Dermatology Advisor: What are some of the foods that have been associated with exacerbating AD symptoms? How much clinical evidence supports this association?

Dr Lio: Many foods have been associated with exacerbating AD symptoms over the years. Some common foods include cow’s milk, egg, gluten, sugar, nightshades, food-coloring agents, food additives, and preservatives. Many diets have been studied, including low-energy diets, very limited (“few foods”) diets, and even more obscure things like low-sodium, low-calcium, and water diets. It is clear that individuals can become allergic to nearly anything, and that food allergy risk is greatly increased in patients with AD. Undoubtedly, if one is allergic to a food, that can be a trigger for AD and removing true allergies is an important part of avoiding triggers. The evidence is very solid here. The confusing part arises for those who do not have a clear allergy to a food but are convinced or concerned that ingesting the food seems to flare the eczema. In those cases, the literature is fairly strong in demonstrating no significant improvement for the majority of these patients.

However, cow’s milk and egg avoidance seems to have an effect in some patients, even in the absence of a true allergy, and there are numerous case reports and small series that support this. While larger studies have generally not come to the same conclusion, it is certainly possible that a subgroup of patients does respond to such avoidance. 

Dermatology Advisor: How should AD patients be evaluated before making any specific recommendations for dietary modification?

Dr Lio: Ideally, patients who are not responding to the basics for AD care should be evaluated for allergies that could be triggering them. This would include IgE [immunoglobulin E]-mediated allergies (tested by serology and prick testing) and delayed-type hypersensitivity allergies (tested by patch testing). In the case of positive allergens, these should be strictly avoided. For those without clear positive allergens, foods they are concerned about can be avoided, but ideally this is done carefully, one at a time, and for a limited period of time before being introduced. I don’t think anyone would have an issue with a patient who said: “I think asparagus makes me flare, so I avoid it.” The issue is when a patient says: “I’m convinced there is something in my diet so I am only eating mashed potatoes and green tea, and maybe I should cut out the potatoes, too…” This is when I feel things can become dangerous for patients, especially children, who need to eat a varied diet to get proper nutrition.

Dermatology Advisor: What medical problems can patients encounter if they decide to go on restrictive diets without consulting with their physician(s)?

Rajani Katta, MD: Elimination diets have to be undertaken carefully, due to the lack of efficacy in many cases as well as the risks, particularly in children. With dairy restriction, we’re concerned about the loss of a nutritious source of protein and fat. In fact, there have been case reports of kwashiorkor developing in young children fed rice milk in place of dairy. With gluten restriction, I am concerned about the loss of the fiber and phytonutrients in whole wheat, as well as the substitution of highly processed gluten-free substitutes.

Dermatology Advisor: How much clinical evidence supports the role of dietary supplements in alleviating the symptoms of AD?

Dr Katta: Synbiotics appear to be a promising adjunct treatment for AD, although there are many unanswered questions. Synbiotics are a combination of probiotics (which contain live, beneficial microbes) and prebiotics (which support the growth of beneficial microbes). In one meta-analysis⁸ that looked at published randomized controlled trials of synbiotics for the treatment of AD, use of these supplements for at least 8 weeks with mixed-strain bacterial species did have a significant effect on improving the SCORAD [scoring atopic dermatitis] index. This held for adults and children aged 1 year and older. 

Dermatology Advisor: What types of studies still need to be conducted before specific recommendations about the use of dietary supplements for AD can be made?

Dr Katta: There are multiple unanswered questions about synbiotics. The meta-analysis mentioned earlier evaluated trials that used a variety of bacterial strains, at different doses and at different dosing regimens. All of these variables need to be studied further before we can recommend specific supplements. With probiotics, we also need more research about specific formulations, especially regarding shelf stability of the product as well as viability of the microbes in the GI [gastrointestinal] tract. Further research is also needed on the ideal type and dose of prebiotics, as those also varied markedly in the meta-analysis.  

References

1. Hulshof L, van’t Land B, Sprikkelman AB, et al. Role of microbial modulation in management of atopic dermatitis in children. Nutrients 2017;9(8):E854.
2. Nosrati A, Afifi L, Danesh MJ, et al. Dietary modifications in atopic dermatitis: patient-reported outcomes. J Dermatolog Treat. 2017;28(6):523-538.
3. Lim NR, Lohman ME, Lio PA, et al. The role of elimination diets in atopic dermatitis: a comprehensive review. Pediatr Dermatol. 2017;34(5):516-527.
4. Tait C, Goldman RD. Dietary exclusion for childhood atopic dermatitis. Can Fam Physician. 2015;61(7):609-611.
5. Shokeen D. Influence of diet in acne vulgaris and atopic dermatitis. Cutis. 2016;98(3):E28-E29.
6. Shikino K, Ikusaka M, Yamashita T. Vitamin D-deficient osteomalacia due to excessive restrictions for atopic dermatitis [published online July 4, 2014]. BMJ Case Rep. doi:10.1136/bcr-2014-204558
7. Kim J, Kwon J, Noh G, et al. The effects of elimination diet on nutritional status in subjects with atopic dermatitis. Nutr Res Pract. 2013;7(6):488-494.
8. Chang YS, Trivedi MK, Jha A, et al. Synbiotics for prevention and treatment of atopic dermatitis: a meta-analysis of randomized clinical trials. JAMA Pediatr. 2016;170(3):236-242.