Researchers are investigating whether excluding certain foods from the diet can help treat childhood eczema.
Dr. Fiona Bath-Hextall and her team from Nottingham University, UK, explain that allergic eczema is a very common inflammatory skin disease of childhood. Its symptoms include dryness and recurring skin rashes with redness, swelling, itching, crusting, flaking, blistering, cracking, oozing, or bleeding.
The experts say that food sensitivities may predate allergic diseases such as atopic eczema in up to 20 percent of cases. Previous research suggests that elimination of specific foods can significantly improve children’s eczema. Animal studies also suggest that eczema may be caused by food allergies.
“It is important to investigate whether the elimination of dietary triggers could help to alleviate the symptoms of atopic eczema,” the team write in the journal Allergy, especially as dietary interventions “address one of the primary causes, as opposed to merely suppressing the symptoms.”
The researchers performed a systematic review of all relevant randomized controlled trials. They found nine suitable studies involving a total of 421 children. Six studies excluded eggs and milk, one a range of foods, and two were studies of an elemental diet, that is, a liquid diet of the basic nutrients.
Unfortunately, there appeared to be no overall benefit on eczema symptoms. But the team writes, “There may be some benefit in using an egg-free diet in infants with suspected egg allergy. This perhaps highlights the importance of allergy testing beforehand. Not showing any benefit from such dietary exclusions in unselected people does not mean they are not helpful in people with proven allergy to that particular food.”
They conclude, “Despite their frequent use, we find little good quality evidence to support the use of exclusion diets in atopic eczema.”
They also warn that elimination diets can be difficult to follow, and there can be serious consequences to any changes in diet which leave the child low in calories, protein or minerals such as calcium. “Many parents experiment by excluding particular foods suspected of causing a reaction,” they write, but “avoidance of multiple foods is potentially hazardous and requires continued pediatric and dietary supervision.”
On the other hand, they point out that their analysis focused on dietary exclusion, and did not answer the question of supplements including probiotics. This issue was addressed in a separate analysis by the same team.
Reporting this time in the journal Clinical and Experimental Allergy, they write, “Probiotics have been proposed as a treatment for eczema, but the results of intervention trials have been mixed.” They reviewed 12 trials including 781 participants.
An analysis of the results of five of the trials showed “no significant reduction in eczema symptoms with probiotic treatment compared with placebo.” Combined analysis of the other seven trials also showed no benefit. Neither did a subanalysis of participants with different eczema severity, or those with or without allergy.
They conclude that, “Currently, probiotics cannot be recommended for treating eczema, butnovel probiotic strains may still have a role in eczema management.”
Dr. Robert Boyle, of Imperial College Healthcare NHS Trust, London, UK, took part in the probiotics study. In a statement for NHS Evidence, Dr. Boyle summarizes the knowledge on probiotics and prebiotics for eczema.
He explains that the composition of the gut flora is different in infants who develop eczema from those who do not. This led to the idea that altering the gut flora using probiotics and prebiotics may treat or prevent eczema.
Probiotics are tiny living organisms. The Lactobacillus or Bifidobacterium strains are often used as potential treatments. Prebiotics are compound sugars, or “oligosaccharides,” which promote gut flora such as Bifidobacteria.
Studies often find no overall benefit, he writes. However, in one trial, prebiotic treatment was found to be effective for eczema prevention. This trial specifically involved infants with a family history of allergic disease, who had been formula-fed within two weeks and completely stopped breast feeding before six weeks. This group may genuinely benefit, he believes.
“Further prebiotic eczema prevention trials are underway internationally,” he writes. “If prebiotics do have a role in eczema prevention, their role is likely to be as an additive to infant formula, where exclusive breast feeding cannot be maintained during the first weeks of life.”
Although probiotics have not been found to prevent eczema, they “remain a subject for further investigation,” Dr. Boyle said.
“The use of prebiotics or probiotics for preventing eczema is an exciting area of study,” he concludes. “Systematic reviews suggest that such treatments are not yet at a stage where they can be recommended for use in clinical practice, but there are grounds for optimism that they will play a role in future strategies for eczema prevention.”
Bath-Hextall, F., Delamere, F. M. and Williams, H. C. Dietary exclusions for improving established atopic eczema in adults and children: systematic review. Allergy, published online January 16, 2009.
Boyle, R. J. et al. Probiotics for the treatment of eczema: a systematic review. Clinical and Experimental Allergy, Vol. 39, August 2009, pp. 1117-27.