According to a new study, growing up in a big family or living with dogs may reduce the risk of inflammatory bowel disease
According to new research presented at Digestive Disease Week (DDW) 2022, young children who grow up with a dog or in a big family may have some protection later in life against Crohn’s disease, a prevalent inflammatory bowel disease.
“Our study seems to add to others that have explored the ‘hygiene hypothesis’ which suggests that the lack of exposure to microbes early in life may lead to a lack of immune regulation toward environmental microbes,” said Williams Turpin, Ph.D., the study’s senior author and a research associate with Mount Sinai Hospital and the University of Toronto.
Nearly 4,300 first-degree relatives of Crohn’s patients who participated in the Crohn’s and Colitis Canada Genetic, Environmental, and Microbial (CCC-GEM) project provided information through an environmental questionnaire. Dr. Turpin and his team examined a number of environmental factors, such as family size, the presence of dogs or cats as household pets, the number of bathrooms in the home, living on a farm, consuming unpasteurized milk, and drinking well water, using responses to the questionnaire and historical data gathered at the time of recruitment. Age at exposure was also included in the analyses.
The research discovered that exposure to dogs, particularly between the ages of 5 and 15, was associated with healthy gut permeability and a balance between the body’s immune response and the microbes in the gut, both of which could help prevent Crohn’s disease. All age groups experienced the same, similar effects from dog exposure.
“We did not see the same results with cats, though we are still trying to determine why,” Dr. Turpin said. “It could potentially be because dog owners get outside more often with their pets or live in areas with more green space, which has been shown previously to protect against Crohn’s.”
Another protective factor seemed to be living with three or more family members in the first year of life, which was associated with microbiome composition later in life. The gut microbiome is believed to play a role in a number of health conditions, such as inflammatory bowel disease, colorectal cancer, diabetes, and high blood pressure.
Dr. Turpin and his colleagues hope their findings may assist physicians in asking detailed questions of patients to determine who is at the highest risk. However, he noted that the early life environmental factors were assessed by questionnaires, so caution is warranted in interpreting these results due to possible recall bias at recruitment. The reasons dog ownership and larger families appear to provide protection from Crohn’s remain unclear.
Crohn’s disease is a type of inflammatory bowel disease that affects around half a million people in the U.S. It most often develops in young adults, people who smoke, and those with a close family member who has IBD. Symptoms include diarrhea, abdominal pain, and weight loss. Treatments currently aim to prevent symptom flare-ups through diet modification, medication, and surgery.
Meeting: Digestive Disease Week 2022