Dietary exclusions may modestly improve atopic dermatitis symptoms
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Patients with mild to moderate atopic dermatitis experienced slight and potentially unimportant improvements with dietary elimination, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
But these improvements should be balanced against risks that elimination diets present, the researchers continued.
“The role of diet in atopic dermatitis, also commonly known as eczema, has long been debated with conflicting views as to the use of dietary elimination as a treatment,” Paul Oykhman, MD, MSc, FRCPC, assistant clinical professor (adjunct) of medicine in the division of clinical immunology and allergy at McMaster University, told Healio.
“To optimally inform patients, caregivers and clinicians, our international team comprised of multiple stakeholders systematically reviewed the benefits and harms of dietary elimination as a treatment for atopic dermatitis,” Oykhman said.
The researchers analyzed 10 randomized controlled trials (n = 599; 44% female) with a mean number of 60 patients each (range, 15-113).
Dietary eliminations ranged from 2 to 32 weeks. Four of these studies eliminated foods due to positive testing and/or oral food challenges. The other six eliminated foods regardless of food-specific IgE sensitization or histories of reactions to the eliminated foods. Examples of foods eliminated include cow’s milk, egg, meat, rice potato, brassica (cabbage), fruit, peanut, cashew, cod and/or wheat.
All 10 studies examined the effect of dietary elimination on eczema severity using SCORing Atopic Dermatitis, or SCORAD, for which an 8.7-point improvement was considered a minimally important difference (MID).
Among 547 patients with these data, a greater proportion of those who participated in dietary elimination achieved this MID than those who did not eliminate foods (50% vs. 41%; risk difference, 9%; 95% CI, 0-17). However, the researchers also noted that these results had low certainty.
Based on daytime itch scores, three of the studies (n = 157) found that dietary elimination slightly improved skin pruritis compared with no dietary elimination (mean difference, –0.21; 95% CI, –0.57 to 0.15). These results also had low certainty, the researchers wrote.
Two studies (n = 77) found that dietary elimination slightly reduced sleeplessness compared with no dietary exclusion (mean difference = –0.47; 95% CI, –0.8 to –0.13), although these results again had low certainty.
Considering the slight effect that dietary elimination had on eczema severity, through ingestion or contact, food may be a minor contributor to the causes and perpetuation of AD, with allergic or nonallergic mechanisms, according to the researchers.
There were insufficient data from the studies to draw conclusions about the development of new food allergies mediated by IgE with dietary elimination, the researchers continued, although indirect data suggested an increased risk. The reporting on the nutritional effects of dietary elimination was limited as well, the researchers said.
The evolving perspective of the role of diet in the development of AD has left some patients finding their conversations with their care providers unhelpful, the researchers wrote, leading to unsupervised and potentially harmful dietary eliminations.
“Whereas patients and caregivers often report a strong suspicion of diet influencing their eczema severity, many clinicians cast doubt out of concern from confounding from other triggers or eczema flare independent of external factors and avoiding harms that can occur with dieting practices,” Oykhman said.
“Our findings support both perspectives having valid aspects. With our data, patients, caregivers and clinicians are no longer left guessing about the outlook with or without pursuing a diet for eczema and can now have an informed conversation together,” he continued.
In addition to the possible risk for developing an IgE-mediated food allergy, the researchers wrote, dietary eliminations could have negative impacts on quality of life, nutrition and growth. They also could dissuade patients from seeking more effective treatment for their AD.
As a result, the researchers concluded, patients need to be fully informed as they weigh the modest benefits in eczema severity, pruritis and sleeplessness that may come with dietary elimination against its potential risks.
“Many fully informed patients may not consider worthwhile a slight improvement in eczema control against the potential for developing anaphylactic-type food allergy, particularly given an increasing number of therapeutic options to treat atopic dermatitis,” Oykhman said. “Thus, the health benefits, harms and practical implications of dietary elimination should be carefully weighed in a shared-decision making framework.”
These findings will inform upcoming guidelines from the American Academy of Allergy, Asthma & Immunology and American College of Allergy, Asthma & Immunology Joint Task Force on Practice Parameters on AD, Oykhman said.
“We also highlight the important need for robust randomized controlled trials to further improve the evidence regarding all benefits and harms of diets for atopic dermatitis,” Oykhman said.
For more information:
Paul Oykhman, MD, MSc, FRCPC, can be reached at paul.oykhman@medportal.ca.
Reference:
- Adjusting diet has pros and cons for treating eczema, study says. https://healthsci.mcmaster.ca/news-events/news/news-article/2022/07/19/adjusting-diet-has-pros-and-cons-for-treating-eczema-study-says. Published July 19, 2022. Accessed July 25, 2022.
Perspective
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Overall, these findings are not surprising, largely paralleling my clinical experience. However, the results are significant, as this report provides updated, rigorous analysis on the role of dietary elimination in treating AD.
Questions about the role of dietary elimination in treating AD are common in the clinical setting, and this analysis clearly lays out how evidence that plays a significant role in treating AD is lacking.
Doctors can use these findings to improve care by counseling patients with AD, and parents of children with AD, that eliminating specific foods from their diet is not likely to do the heavy lifting in terms of successfully treating their disease. Rather, focusing on using safe and effective medical treatments is likely to have a more meaningful impact.
Next steps in this research could be to evaluate if there is a clear subset of patients who do respond more substantially to dietary intervention and, if so, how to identify them consistently.
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