You may have seen the headlines all over the internet in the last week, proclaiming that new research shows that cleaning your baby’s pacifier by sucking on it after it is dropped may provide protection against developing allergies.
Of course, studies like this are often reported in the news in a way designed to get your attention and be exciting, not necessarily in a way that gets all the facts right. Nuance does not drive clicks. As usual, it’s worth taking a deeper look to see what new data the study actually shows and how the new study’s data fits with existing high-quality data.
As so often happens, we think we know something with a high level of certainty, and new information comes out that complicates or challenges existing beliefs. This data—which shows potential benefits from exposure to everyday germs—yet again challenges our modern American conception that favors keeping all germs away from babies at all times, even “protecting” them from run-of-the-mill household germs. This study appears to add to the growing body of evidence that keeping children in an ultra-clean environment is probably not helpful for children’s immune systems as they grow up. Some exposure to dirt, garden-variety bacteria and other microbes is normal and healthy.
If you look at humans through a historical lens, we did not live and grow in particularly germ-free environments. The thought of trying to keep an infant from being exposed to the natural environment is not a logical development. Children crawl on the ground. They put everything into their mouths. It’s possible that these behaviors aren’t just a growth and development process; maybe these behaviors serve a bigger purpose in building a healthy immune system.
One thing we know very well from a body of well-established research is that the spread of dental caries from mother to child is well documented. The microbes responsible for dental caries get transferred from the mother or other primary caregivers quite readily. So, picking up a baby’s pacifier that fell onto the floor and putting it in the mother’s mouth to clean it is a clear avenue for transferring this disease, just like kissing, sharing drinks, sharing silverware, and other common human behaviors. One of the most important ways a mother can help prevent dental caries in her child is to have a healthy mouth herself. Oral health needs to be considered from a whole family perspective to be most effective. We shouldn’t just focus on treating the child to prevent oral health concerns but need to address any caries disease in the mother as well.
It’s important to remember that this study is very limited, and you really can’t draw definitive conclusions from it. The sample size, the number of people studied, was very small. The study also was not designed to prove cause and effect It does, however, further questions raised by the “hygiene hypothesis”. The hygiene hypothesis proposes that children who live in less than immaculate environments where they are exposed to germs earlier develop healthier immune systems and are better able to fend off infections while being less likely to develop autoimmune diseases (asthma, eczema, allergies, etc.) than infants and children raised in completely germ-free environments.
Further, there are ways that have shown promise in reducing allergies in children that have not been associated with increasing the risk of developing caries. For example, contrary to previous advice, the American Academy of Pediatrics has issued guidelines for introducing peanuts to children as early as four months. It turns out that introducing peanuts early actually decreases the likelihood of developing a peanut allergy. The American Academy of Allergy, Asthma, and Immunology, after examining the whole body of relevant research, notes that breastfeeding when possible for at least the first four months provides some protection from developing asthma and allergies. They also recommend introducing allergenic foods sooner rather than later to avoid developing food allergies. None of these research-based actions increase the risk of introducing cariogenic bacteria to the child.
There was a similar report issued a few years ago that examined the 5-second rule. The 5-second barrier was shown to be quite arbitrary, not a meaningful measure of contamination or safety. Perhaps we should be less concerned about the contamination of things falling on the floor and more concerned about the contamination likely if mom has dental caries.