Scientist - News - 30-11-2009:

Probiotics and eczema in high-risk children
Beintema, Nienke

A mixture of Bifidobacterium bifidum, B. lactis and Lactococcus lactis helps to prevent eczema in children with an increased risk of developing atopic diseases. Titia Niers recently defended her thesis on this subject, at Utrecht University.

Atopic diseases, such as eczema, asthma, food allergy and hay fever, are common in Western society, particularly among children. Around 20 to 30 percent of children are estimated to suffer from these conditions to some degree. Scientists from Utrecht University set up a randomized, double blind and placebo-controlled study to look into the potential effect of probiotics on the incidence of these atopic diseases in high-risk children. This study, called the PandA (Probiotics AND Allergy) study, has yielded several scientific publications and a PhD thesis. Titia Niers, pediatrician-in-training, successfully defended this thesis on November 10.
“There has been very little research on the potential effect of probiotics on atopic diseases," says Niers. "Besides, these studies have used different set-ups and different strains of probiotics, so it is difficult to make valid comparisons." The Utrecht study used three probiotic strains, Bifidobacterium bifidum, B. lactis and Lactococcus lactis, which in vitro experiments had identified as the most likely candidates to have the desired effect.

First three months
"In total, we followed around 100 high-risk families throughout the study," explains Niers. "Expectant mothers used this selected mixture of probiotic bacteria in the last six weeks of their pregnancies, and their babies were given the probiotics for one year after birth. We examined the parent-reported incidence of atopic diseases at ages 3 months, 1 year and 2 years. At 3 months, we also studied the children's gut microbiota as well as several immune parameters."
The results, as Niers points out, showed that the probiotic mixture did have a significant effect on the incidence of eczema in the first three months of life. During the subsequent period, the difference remained present but was no longer significant. "We would have needed a larger study group to keep the difference significant," she notes, "but in any case we were able to show that the absolute risk reduction persisted. We therefore conclude that the effect seems to be sustained during the first two years of life."

Composition
For the other atopic diseases, Niers was unable to show a significant difference. "Conditions such as asthma and hay fever," she notes, "usually manifest themselves later in life, so that may be an explanation. We will follow these children until they are 6 years old, so perhaps this follow-up will shed more light on this question."
At age 3 months, Niers and her colleagues were able to show significant differences in the composition of the gut microbiota between the experimental and control groups. "The amounts of the three probiotic strains were indeed increased in the probiotics group," says Niers. "This is of course what you'd expect, but it is still nice to be able to actually show it. We also looked at the relative abundance of other bacterial strains in the gut microbiota, but these data have not yet been published."

Too early
The probiotic group also showed a difference in an important immune parameter. "The production of IL-5 was reduced in this group at the age of 3 months," says Niers, "and we know from previous research that IL-5 is implicated in the pathogenesis of atopic diseases in general. But further research is needed in order to determine to what extent this parameter can actually be used as an indicator or predictor of eczema or other atopic diseases."
Similarly, as Niers underlines, it is too early to recommend that probiotic bacteria in general be used by all high-risk children. "Our research has revealed some important information," she says, "but further research is needed to determine, for instance, the underlying mechanisms and the optimal way of using these probiotics for this purpose. But some important small steps have been made, and the results are definitely promising."

More information:
The PandA study
Recent publication by Niers et al. in the journal Allergy (Sept. 2009)