Researchers from the University of Gothenburg in Sweden report that parental saliva on a baby's pacifier may provide significant protection against allergy development in the infant.
Allergies are becoming increasingly common in children from industrialized countries. Health experts believe that exposure to harmless bacteria during infancy may offer a protective effect, but pinpointing which bacteria a baby should be exposed to has proven to be a tricky exercise.
For this study, the researchers registered how many infants used a pacifier in the first 6 months of life and how the parents cleaned the pacifier. Most parents rinsed the pacifier in tap water, or boiled it, before giving it to the baby. However, some parents had the habit of putting the baby's pacifier into their mouth and cleaning it by sucking, before returning it to the baby.
The researchers found that children whose parents habitually sucked the pacifier were three times less likely to suffer from eczema at 2 years of age. When controlled for other factors that could affect the risk of developing allergy, such as allergic parents and delivery by Caesarean section, the beneficial effect of parental sucking on the pacifier remained. The researchers' findings appear in the journal Pediatrics.
Saliva is a very rich source of bacteria and viruses, and the researchers believe that oral microbes are transferred from parent to infant when they suck on the same pacifier. When the composition of the bacterial flora in the mouth was compared between infants whose parents sucked on their pacifiers and those whose parent did not, it was found to differ, supporting this hypothesis.
According to the hygiene hypothesis, the development of allergy can be attributed in part to a lack of microbial stimulation during early infancy. "Early establishment of a complex oral microflora might promote healthy maturation of the immune system, thereby counteracting allergy development," speculates Agnes Wold, who led the study.
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Source: University of Gothenburg