A new study says sucking a baby's pacifier clean may lead to a reduced risk of allergies and asthma. 
baby hand with pacifier

How do you clean your baby's pacifier when it falls to the ground? If you pop it into your own mouth, you may be benefiting his health.

A new study from the Henry Ford Health System reports infants whose parents sucked on their pacifiers to clean them developed less allergies and asthma than children whose parents typically rinsed or boiled them. The infants had less of the antibody Immunoglobulin E (IgE), which is associated with the health conditions.

“Although we can’t say there’s a cause and effect relationship, we can say the microbes a child is exposed to early on in life will affect their immune system development,” says the study’s author Eliane Abou-Jaoude, M.D., a Henry Ford allergist fellow, in a statement. In theory, the mother is passing healthy bacteria – found naturally in her saliva  – to Baby, which strengthens his immune system.

The study followed 128 mothers with different cleaning methods for their child’s pacifiers: boiling with hot water, washing with soap, and sucking. IgE levels were then tested at birth, six months, and 18 months. “From our data, we can tell that the children whose pacifiers were cleaned by their parents sucking on the pacifier, those children had lower IgE levels around 10 months of age through 18 months of age,” says Dr. Abou-Jaoude. Lower IgE levels correlate to a decreased risk of asthma and allergies.

These findings add to growing evidence that some degree of exposure to germs at an early age benefits children, and that microbial deprivation might backfire, preventing the immune system from developing a tolerance to trivial threats. In fact, a 2013 study from Sweden also reported on the connection between reduced allergy risk when sucking a pacifier clean.

Despite the Henry Ford Health System’s findings, parents should exercise common sense when cleaning pacifiers that have been dropped into very germ-laden situations, such as a garbage can or bathroom floor. Dr. Abou-Jaoude also notes that more research is needed before making a definite conclusion on the matter.