Children with pet dogs have a lower risk of Crohn’s disease • Broader climate change mitigation strategy urgently needed A new study published in the journal Proceedings of the National Academy of Sciences has found that, by itself, slashing emissions of carbon dioxide is not enough to prevent catastrophic global warming. However, a strategy that would simultaneously reduce emissions of other largely neglected climate pollutants – including methane, hydrofluorocarbon refrigerants, ground-level ozone smog, black carbon soot, and nitrous oxide – could cut the rate of global warming in half by 2050. According to the Intergovernmental Panel on Climate Change (IPCC), cutting fossil fuel emissions (the main source of carbon dioxide) by decarbonizing the energy system and moving to renewable energy would actually increase global warming in the short term, if such measures are taken in isolation. Since burning fossil fuels also emits sulphate aerosols - which have a significant role in cooling the climate – switching to clean energy sources may result in “weak, near-term warming” that could potentially cause temperatures to exceed the 1.5°C level by 2035 and the 2°C level by mid-century. However, a dual strategy that simultaneously reduces the non-carbon dioxide pollutants would enable temperatures to stay well below the 2°C limit, and significantly improve the chance of remaining below the 1.5°C target set at the Paris Agreement in 2015. Such pollutants currently contribute nearly as much to global warming as carbon dioxide and, since most of them remain only a short period of time in the atmosphere, cutting them could halt warming faster than any other strategy. While continuing to slash carbon emissions will remain vital – since such actions will determine the fate of the climate in the long-term, and would reduce the air pollution which kills over eight million people each year and causes billions of dollars of damage to crops worldwide – tackling short-lived pollutants too is the only hope of humanity making it to 2050 without triggering irreversible and possibly catastrophic climate change. Thus, the development of climate policies to address all of the pollutants that are emitted from fossil fuel sources, such as coal power plants or diesel engines, is urgently needed to give the world a fighting chance to keep global warming at manageable levels.

Children with pet dogs have a lower risk of Crohn’s disease

Children who grow up in a large family, or with a pet dog, may have some protection from Crohn’s disease, according to a new study from the American Gastroenterological Association.

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 irritable bowel syndrome. Symptoms include diarrhea, abdominal pain and weight loss. Treatments currently aim to prevent symptom flare-ups through diet modification, medication, and surgery.

“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 lack of immune regulation toward environmental microbes,” said study senior author Dr. Williams Turpin, a research associate with Mount Sinai Hospital and the University of Toronto.

An environmental questionnaire was used to collect information from nearly 4,300 first-degree relatives of people with Crohn’s disease enrolled in the Crohn’s and Colitis Canada Genetic, Environmental, and Microbial (CCC-GEM) project. 

The research team analyzed several environmental factors, including family size, pet dogs or cats, the number of bathrooms in the house, living on a farm, drinking unpasteurized milk and drinking well water. The analysis also included age at the time of exposure.

The results showed that exposure to dogs from ages 5 to 15 was linked to healthy gut permeability and balanced microbes in the gut and the body’s immune response. These factors are all likely to help protect against Crohn’s disease. In other age groups that had exposure to dogs, similar effects were observed.

Interestingly, the research team did not find the same association with pet cats. “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,” said Dr. Turpin. 

The findings also suggest that living with three or more family members in the first year of life was associated with microbiome composition later in life. It is not yet clear why dog ownership or living in a larger family provides protection from Crohn’s.

The gut microbiome is believed to play an important role in many health conditions such as inflammatory bowel disease, colorectal cancer, diabetes, and high blood pressure.

Dr. Turpin and his colleagues hope their work can help physicians when diagnosing patients with Crohn’s disease to help determine risk. 

The research will be presented at Digestive Disease Week (DDW) 2022.

By Katherine Bucko, Staff Writer

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