Prebiotics in infants for prevention of allergic disease and food hypersensitivity

Many parents add prebiotics and probiotics to children's food to help treat health problems, and according to two new reviews, the supplements might also help prevent eczema in babies at high risk.

Still, research in this area is in its infancy, the review authors say.

Food reactions and allergic diseases, such as asthma and eczema, are common problems for children, and might be becoming more prevalent in developed countries. Estimates indicate that 15 percent to 20 percent of children worldwide will develop eczema.

Researchers are currently examining ways to prevent these conditions, and one theory is to improve the health of the body's natural immune system to fight allergens better. Probiotics are dietary supplements that contain healthy bacteria or yeast that can help restore the body's natural balance, and prebiotics are indigestible food components that also stimulate the growth of the body's healthy bacteria.

The two separate systematic reviews aimed to determine whether these substances could help prevent allergic diseases and food reactions in infants who might be susceptible.

The reviews appear in the current issue of The Cochrane Library , a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.

Dr. John Sinn, review co-author, said that while prebiotics and probiotics are used to treat conditions in children, such as diarrhea, the practice of using them to treat children's allergies and food hypersensitivities is still growing. Sinn is a senior staff specialist at the Royal North Shore Hospital in Australia.

“Probiotics and prebiotics are common items on the shelves of natural food outlets and their use in infants is not new, as breast milk contains some probiotics and prebiotics,” Sinn said. “The concept, however, of adding probiotics and prebiotics to an infant's diet to prevent allergy is still in its infancy and more studies are needed to confirm the limited benefits shown so far.”

To examine the effectiveness of probiotics, the Cochrane reviewers analyzed 12 studies, six of which reported outcomes of 1,549 infants who were up to 6 months old and did not show any signs of having allergic diseases or food hypersensitivities. Researchers compared infants who ingested probiotics added to breast milk or formula to those in a control group given a placebo or no treatment at all.

The mother typically took the probiotics during the last weeks of pregnancy and when breastfeeding, or added the probiotics to formula for the first 6 months.

The reviewers found that probiotics might help prevent eczema in infants and one study suggested this benefit might last up to four years of age. The studies showing the most significant benefits were those containing the probiotic Lactobacillus rhamnosus.

“Studies using Lactobacillus rhamnosus showed some benefit in preventing the onset of eczema,” Sinn said. “However, the benefits were not shown in other common allergic symptoms such as asthma, allergic rhinitis, food hypersensitivity and food allergy.”

In the companion review on prebiotics, seven studies were included but only two reported on the outcomes of allergies for 432 infants. The studies also compared infants who had prebiotics added to breast milk or infant formula for six months to a control group given either a placebo or no treatment at all.

“The oligosaccharides used in the studies were a combination of galactose oligosaccharide and fructose oligosaccharide,” said Sinn. “In the studies that analyzed allergy as an outcome, the Galactose oligosaccharide was made from lactose and the Fructose oligosaccharide was made from chicory root [an herb], all of which are natural substances.”

The only study that found some significant improvement in the prebiotics group was one that showed a reduction in eczema to infants who were at high risk for the disease.

The reviewers, therefore, concluded that there was insufficient evidence to recommend that physicians routinely add probiotics or prebiotics to infants' milk or formula to prevent allergies, and point to a need for further research in this area.

“At this time, probiotics seem promising, but the evidence is preliminary,” agreed Sunita Vohra, MD, an associate professor in the department of pediatrics at the University of Alberta. She wrote a recent Cochrane review on probiotics for treating antibiotic-associated diarrhea. “These reviews allow clinicians to be aware of potential new therapies, so they can decide if the risk-to-benefit profile is appropriate for their patients.”

Both reviews disclose that Sinn has been an invited speaker to industry-funded meetings.

The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.

Osborn DA, Sinn JK. Prebiotics in infants for prevention of allergic disease and food hypersensitivity. Cochrane Database of Systematic Reviews 2007, Issue 4.