Eliminating foods in an effort to control atopic dermatitis in children may do more harm than good, according to a review of the topic presented at the 2019 American Academy of Dermatology Annual Meeting which ends in Washington today.
“Many families come in convinced that food is the root cause of eczema,” presenter Peter Lio, MD, of Northwestern University Feinberg School of Medicine in Chicago told Elsevier’s PracticeUpdate. “… Sadly, many of these families have already tried various dietary modifications—usually without success—but still want to know more about it. In the most severe cases, I have seen children with serious malnutrition from hyper-exclusive diets like only taking rice milk. Tragically, the eczema tends to be as bad as ever, though I think the cognitive dissonance is so powerful that a common report is a hopeful, ‘it was a little bit better.’”
Dr. Lio pointed out that there are good data demonstrating that excluding foods in unselected patients with atopic dermatitis offers no benefit. “I am quite convinced that diet is not a major factor in driving their skin disease,” he continued. “We wrote a pretty comprehensive review last year and looked at many papers over many years, and I would say that this supports my clinical experience.”
While the severity of atopic dermatitis correlates with food allergy, this does not mean that food allergy is a cause of the atopic dermatitis. In fact, 80% of patients do not experience a worsening of their atopic dermatitis due to food allergy. Patient reports of adverse reactions to food can be unreliable, as patients perceive adverse reactions to food at 10 times the rate of their true prevalence.
It can be tempting to go along with parents who want to try an elimination diet to see if it helps, but one must be cautious, said Dr. Lio. In addition to risks of malnutrition in the most extreme cases, food elimination diets can place patients at increased risk of developing anaphylactic reactions to foods. One retrospective review of 298 patients who avoided previously tolerated foods in an effort to treat their eczema found that, when these foods were reintroduced, 19% had symptoms of acute IgE reactions, and, of these, 30% were classified as anaphylaxis.
The good news is that treating the atopic dermatitis can also treat parental concerns about food allergy. In one study, both parental concern about food allergy and estimated food reactions decreased substantially among parents of children receiving topical tacrolimus for their atopic dermatitis.
In addition, said Dr. Lio, “it is now thought that at least some food allergies (such as peanut) actually may be caused by the atopic dermatitis! The thinking is that the impaired skin barrier allows food proteins to abnormally enter the body and thus stimulate allergy. This is exciting to me because it truly takes this story and turns it on its head.”
This means that treating atopic dermatitis and maintaining the skin barrier could reduce the incidence of food allergy. It is extremely important to encourage patients and their parents to moisturize their skin, as regular use of emollient creams and ointments have been shown to be important for controlling atopic dermatitis.