Allergy to cow’s milk affects roughly one in fifty children,
rendering them at risk for potentially deadly allergic reactions as well as for
poor nutrition that comes with avoiding cow’s milk. In this month’s issue of
JACI, Bunyavanich and colleagues relay the results of their research on how gut
bacteria might influence the course of this disease (J Allergy Clin Immunol 2016; 138(4): 1122-1130). They looked at the stools of 234 milk
allergic children ranging in age from 3 to 16 months. They used 16s rRNA
sequencing to profile the different types of gut bacteria and followed the
children up to age 8 years.
They found that among children age 3 to 6 months, bacteria in
the Firmicutes phylum and Clostridia class were associated with
resolution of milk allergy by age 8 years.
This is consistent with preliminary findings from mouse models that also
show that Clostridia have a role in
regulating sensitization to food allergens.
However, these bacteria appear to have a very short time window to exert
their effect, because there was no association in children beyond 6 months of
age. It is possible that the immune
systems of infants up to six months of age are easier to tolerize, or that the
introduction of solid foods at around age 6 months obscures this association.
It is possible that the fatty acids produced by bacteria may
have potent roles in reestablishing tolerance, but the study was not structured
to answer that question. Other questions
left to answer include whether supplementation with probiotics can help reestablish
tolerance and whether introducing these bacteria would be safe.
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