For most families that own pups, parents don’t mind it so much when their adorable doggy slobber all over their kid’s faces, even if it doesn’t seem that hygienic. But apparently, this might not be such a bad thing at all. A new study shows that it could even give an additional layer of protection against Crohn’s disease for these kiddies.
The research, which has yet to be published, was presented as the Digestive Disease in San Diego last May made a play for the ‘hygiene hypothesis,’ which is an idea that talks about how kids with exposure to germs actually build better and stronger immune systems. The study authors discovered that kids that grew up with dogs, or in rather big families, were actually at a lower risk of developing Crohn’s disease.
The study began in 2008, and is still ongoing, with researchers using questionnaires to gather information and data from over 4,200 parents, siblings, or children of people diagnosed with Crohn’s disease. This high-risk group also participated in the GEM Project, or the Crohn’s and Colitis Canada Genetic, Environmental, and Microbial Project. The study showed that after 5.6 years, at least 86 study participants developed Crohn’s disease. The team also looked at all the environmental factors, such as family size, if participants grew up on a farm, drank raw or pasteurized milk, if they drank municipal water or well water, how many bathrooms they had at home, as well as if they had household pets – either cats or dogs.
The study’s senior author and research associate with Mount Sinai Hospital and the University of Toronto, Williams Turpin, PhD, “We really want to get a clearer picture of the environmental factors that either protect against or contribute to Crohn’s disease. That way we hope to develop interventions to reduce risks in the population.”
Turpin and his study colleagues chose to focus on family size and pet ownership when it came to the study participants. In order to get accurate results, they tested gut function using urine tests that measure how sugar is passed through the colon. What they found was that for those with exposure to dogs at any age, there was an association with better gut function. Meanwhile, for those people that had dogs between the ages of 5 and 15, the odds of developing Crohn’s disease actually dropped by a whopping 40 percent.
However, owning a cat had no effect, while those that currently owned birds actually had a slightly higher risk of developing Crohn’s. Yet, they also note that not enough people in the study actually owned a bird to explain if there was a clear association.
Dr. Turpin explained, “One theory is that the way we interact with dogs is different from other animals. When dogs lick a child’s face, it offers early exposure to germs that the body learns to recognize so there’s not an aggressive immune response when you meet those germs later in life.”
Notably, this statement from Dr. Turpin also aligns with former research including a seminal study on the Science website, that found how early germ exposure was associated with protection from inflammatory bowel disease, as well as asthma. In addition, Frontiers in Immunology published a letter in 2021 that had strong evidence from all around the world that people that grew up around farm animals were linked to lower instances of asthma, ‘an immune-modulated condition also associated with inflammation, just like Crohn’s disease.’
Growing Up in A Big Family May Help Too
The study group also observed how living in a household with at least three or more people as a baby was also linked to ‘a 59 percent lower risk of developing Crohn’s disease.’ For people born into a bigger family, they also seemed to develop higher microbial diversity later on in life, something Dr. Turpin shares is normally considered a sign of a healthy gut microbiome later in life.
Although there isn’t enough definitive proof for why this is the case, Turpin shares, “It’s tempting to speculate that it may be related to increased exposure to microbes early in life. Indeed, increased exposure to environmental microbes especially early life is thought to promote immune tolerance later in life, preventing an exaggerated inflammatory response to those microbes later in life.”
Although the study also revealed that living with dogs lessened your chances of developing Crohn’s disease, what wasn’t found was that people living with dogs also had higher microbial diversity or a superior bacteria makeup within their intestines.
Gastroenterologist and clinical director of inflammatory bowel diseases at Johns Hopkins-Sibly Memorial Hospital in Washington, DC, Aline Charabaty Pishyaian, MD, who wasn’t involved in the study, said, “This part is very interesting because it suggests that environmental factors don’t shape what microbes we have, but it probably affects how strong certain microbes are that may elicit a pro-inflammatory or anti-inflammatory response.”
In addition to this, a gastroenterologist and assistant professor of medicine at NYU Langone Health in New York City, Rabia De Latour, MD, who was also not involved in the study, said, “A study like this is very thought-provoking and can show us some associations that are worth further examination. The hope is that other researchers will see this, get a spark of an idea, and carry out the research that will fill in the missing pieces.”
They also share that with added evidence, there could be a better chance to find ways to protect people from developed Crohn’s disease later on in life.
For the time being, both gastroenterologists, Pishvaian and De Latour recommend allowing kids to play outside and get dirty, as well as lessening the use of antibiotics. This will help them gain better gut microbiome, as well as a stronger immune system.
“I always tell new parents to practice reasonable hygiene, but don’t stress when their baby puts her dirty hands in her mouth. The more your baby is exposed to, the better it will be for her developing system. It’s wonderful that one of the best ways to develop a healthy gut is just to let a kid be a kid,” adds Dr. Pishvaian.
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