Eczema: Can eliminating particular foods help?
It's not proven that the arbitrary elimination of some foods can relieve eczema symptoms in children who don't have a confirmed food allergy. There has been very little good-quality research on elimination diets in adults with eczema.
Many people try to relieve their eczema symptoms by avoiding certain foods. This is referred to as an "elimination" or "exclusion" diet. Foods often associated with eczema include eggs, milk, fish and peanuts. Sugar and foods containing gluten, on the other hand, don't play any role in the development of eczema. Sometimes, an elimination diet excludes more than just one or two types of food. But excluding certain foods is only a good idea if you've been diagnosed as being allergic to those specific foods (targeted elimination diet).
It's usually very hard to stick to a diet that isn't targeted. And it's often particularly difficult for children if they have to go without things like cake or other goodies. Small children may find it difficult to understand why they can't eat certain things that other children are allowed to eat. It is important that people who are on elimination diets make sure that they still get enough nutrients, minerals and vitamins.
It's difficult to find out whether eczema is being caused by a certain substance because the severity of eczema symptoms varies over time. You might easily get the idea that a specific food triggered a flare-up although the symptoms might have got worse on their own anyway. So eczema flare-ups are often mistakenly associated with certain foods.
Testing for food allergies
Different tests can be used to find out whether someone has allergic (atopic) eczema. The most common are a skin prick test for allergies and a blood test IgE antibodies.
Both tests have limitations though. If the results are normal, you can be quite sure that you don't have an allergy. Abnormal results are more difficult to interpret. They do show that the body is sensitive to the food. But the test can't tell us whether it is causing the eczema or making the symptoms worse. Also, most people react to some substances in these kinds of tests. But that does not automatically mean that they have trouble in their everyday life too.
Because allergy testing gives us such limited results, Germany's Dermatological Society recommends them only if you are thought to have a specific allergy. The test results also need to be interpreted with caution: Abnormal test results are no reason to exclude one food. It's different if a test called the "challenge" test confirms that the skin actually reacts to a certain food.
Research on elimination diets for eczema
Good scientific studies are needed to be able to find out whether or not elimination diets are effective for eczema. Such studies look at what happens when people who have eczema leave certain foods out of their diets. To do this, volunteers with eczema are randomly assigned to two groups. The research participants in one group are asked to keep eating their usual diets, while those in the other group are asked to go on a special diet.
Researchers from the Cochrane Collaboration analyzed nine suitable studies that tested whether elimination diets had any effect on eczema symptoms. Six of the studies looked at diets that avoided eggs and milk. Two of them tested the effect of a liquid baby food reduced to a few nutrients without any allergens. One study looked at a diet made up of only a few foods. The participants were tested for food allergies in only one of these studies.
Most of the studies involved infants and children as participants. Only one involved adults exclusively. The studies were relatively small - the average number of participants was between 11 and 85. All of the studies also had weaknesses: For example, in some of them the participants did not stick to the strict diet properly. Only two studies followed the participants for longer than six months. In half the diets that excluded milk, soy-based milk substitutes were used. This could limit the value of the study outcomes because other research has shown that soy milk can sometimes cause allergies itself.
Elimination diets probably only help in people who have a diagnosed food allergy
In 8 of the 9 studies there was no clear difference between the groups of people who were on a special diet and those who were not. Most of the participants hadn't been tested to see whether they had a food allergy in the first place, though. Generally eliminating foods you are not thought to be allergic to probably doesn't help.
One of the studies looked at babies who had been found to have an allergic reaction to eggs based on a blood test done before the study started. In this study one group of babies had an egg-free diet for four weeks, whereas the other group had a normal diet. The results showed that not eating eggs reduced rashes in the babies, but there were only 62 of them included in the study.
Bath-Hextall F, Delamere FM, Williams HC. Dietary exclusions for established atopic eczema. Cochrane Database Syst Rev 2008; (1): CD005203.
Deutsche Dermatologische Gesellschaft e.V. (DDG). Neurodermitis. S2k-Leitlinie. March 2015 (AWMF-Leitlinien; Volume 013 - 027).
Sidbury R, Tom WL, Bergman JN, Cooper KD, Silverman RA, Berger TG et al. Guidelines of care for the management of atopic dermatitis: Section 4. Prevention of disease flares and use of adjunctive therapies and approaches. J Am Acad Dermatol 2014; 71(6): 1218-1233.
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