Environmental risk factors for IBD

EASYOver the past 60 years, experts have documented the prevalence of both ulcerative colitis and Crohn’s disease — two medical conditions that make up most cases of inflammatory bowel disease (IBD). For decades, this increase was limited to North America, Western Europe, and other industrialized nations. While there is some evidence that the rise of IBD has slowed or even stopped there, IBD is becoming increasingly common in the newly industrializing countries of Asia and other parts of the world. world.

There’s no doubt that genetic factors play a part in a person’s risk of inflammatory bowel disease — and especially for Crohn’s disease. But the increased prevalence of IBD and the distinct geographic patterns of the disease suggest that environmental factors also have an impact. “After World War II, we saw a rapid increase in the incidence of IBD across developed countries,” said Dr Gilaad Kaplan, professor and gastroenterologist at the University of Calgary in Canada. . “Something about the Western lifestyle seems to be allowing this disease to develop.” Is that something? It is an unsolved mystery.

There are several theories — or rather, suspicions. Researchers have found a link between IBD and air pollution, food additives, early life antibiotic exposure, and other environmental variables. Kaplan says that several of these risk factors, not just one, are likely to underpin an increase in IBD. And they all have one thing in common: the gut microbiome. “Most people feel that what drives the inflammatory response we’re seeing, where the body’s immune system attacks the gut, is in the gut microbiome,” he said.

Your digestive tract has billions of microorganisms that are important for gut health and functioning. These bacteria help digest the food you eat, and the metabolites they produce help regulate your immune system. Kaplan said that a strong and Diverse microbiota is a sign of a healthy digestive tract, while anything that upsets or imbalances the microbiome has been linked to gastrointestinal dysfunction, including IBD. “Many of the widely studied environmental risk factors are now being viewed through the lens of the microbiome,” he said. This new perspective yields important insights, including some related to the treatment of IBD.

Here you will find a summary of the environmental risk factors researchers have affiliated with IBDas well as expert guidance on mitigating those risks.

Air pollution and IBD

For a first study published in 2010, researchers examined the link between ambient air pollution and the incidence of IBD. They found that young people who grew up with high levels of nitrogen dioxide were more than twice as likely to grow as other children. Crohn’s disease.

Since that groundbreaking study, more work has linked air pollution to higher rates of IBD. “We found that exposure to both nitrogen dioxide and Ozone in early life is associated with an increased risk.

Both of these pollutants are associated with automobile traffic. Fuel-burning cars and trucks release nitrogen dioxide in their exhaust. When nitrogen dioxide combines with heat and sunlight, it undergoes a chemical reaction that produces ozone. “In areas with a lot of traffic, we can see high levels of this association,” says Lavigne. “Living near those areas can be a risk factor for IBD.”

How can air pollution affect gut health? Research has shown that after inhaling pollutants, the lungs can actually push these substances into the throat for them to be swallowed. This process is called mucosal clearance. Once in the gut, these pollutants can damage the gut microbiome in a way that promotes inflammation, says Lavigne.

Based on his and others’ research, he says that exposure to air pollution during childhood — not in utero or in adulthood — appears to pose the greatest IBD risk. Staying away from high-traffic roads, especially on hot days, is one way to avoid these risks. “Levels of these pollutants were highest within 50 meters” — about 160 feet — “for busy roads,” he said.

Lavigne also examined the impact of parks and other urban green spaces on air pollution hazards. His research shows that children who grow up near green spaces have a reduced risk of IBD. “Airborne particles can be trapped by leaves and so having more trees and greener environments can actually create a buffer that reduces human exposure,” he explains.

Read more: The Link Between IBD and Aging

Food choices and dietary exposure

What you swallow can affect the composition of your microbiome and therefore your gut health. And researchers have identified a number of variables related to diet seems to play a role in IBD risk.

Some of the strongest jobs involve the first foods that babies eat. “Breastfeeding seems to be very important,” says Kaplan. Research has shown that children who are breastfed, as opposed to formula, are 25% less likely to develop IBD. “As an infant, when you have breast milk, there seem to be tangible benefits supporting the development of a diverse and robust microbiome,” he explains.

In addition, there is evidence that the consumption of sugary drinks– soft drinks in particular – increases a person’s risk of developing ulcerative colitis. The more soda someone consumes, the greater their risk. On the other hand, eating vegetables is associated with lower rates of ulcerative colitis, while eating whole fruits or other high-fiber foods seems to reduce a person’s risk of Crohn’s disease.

“There’s also some really interesting research on preservatives that extend the shelf life of foods,” says Kaplan. A 2021 study in the journal BMJ found that higher consumption of ultra-processed foods — soft drinks, but also salty snack foods, processed meats, and other packaged goods — was associated with a sharp increase in IBD. Compared with people who ate less than one serving of these foods per day, those who ate five or more servings were nearly twice as likely to develop IBD.

“Things like emulsifiers and additives and highly processed food particles can lead to microbiome changes that may be associated with IBD risk,” says Kaplan. “Choosing whole grains and staying away from processed or packaged ones can reduce your risk.”

Read more: How to Maintain Your Social Life When You Have IBD

Early hygiene and antibiotics

Antibiotics can save lives when someone has a bacterial infection. But these drugs kill indiscriminately – meaning they kill the good bacteria as well as the bad bacteria. And there’s evidence that when given early while a child’s microbiome is still forming, antibiotics can cause an imbalance that promotes IBD.

The authors of a 2019 research review in the journal wrote: “Antibiotics may alter the composition of the human gut microbiome by reducing faecal abundance and diversity. type. Gastroenterology. They cite work linking early use of broad-spectrum antibiotics – basically anything but penicillin – with a more than 50% increased risk of IBD.

“If you have a bacterial infection, you need antibiotics,” says Kaplan. But too often, these drugs are prescribed when they are not absolutely needed — for example, when a child has a respiratory infection that is likely to go away on its own without antibiotics. Physicians are increasingly aware of the risks posed by the overuse of antibiotics. But parents still need to be vigilant, he said.

Meanwhile, while hygiene is often seen as a good thing – and not only a good thing but a safety measure that has saved countless lives – there is strong evidence that too much cleanliness, especially during infancy and infancy, can actually deplete the gut microbiota. The “hygiene hypothesis,” as it’s called, argues that children who interact with siblings, farm animals, pets, dirt, and other sources of germs tend to have microbial ecosystems. a healthier and more resilient gut, and research has linked all of these factors to lower rates of IBD (as well as allergic and autoimmune diseases).

“First contact of life [to germs] Emeran Mayer, founding director of the Microbiome Center at the University of California, Los Angeles. The theory is that when the developing microbiome encounters germs and bacteria, this exposure trains its sensitivity and response in ways that reduce a person’s risk of IBD. And so raising children in a clean environment and in addition to other children, animals or sources of germs can affect their gut health as well as their immunity. (Some experts have even speculated that COVID-19 safety measures, like heavy use of hand sanitizer, may inadvertently lead to an increase in IBD in young people.)

A complicated puzzle

While researchers have made a lot of progress in studying environmental risk factors for IBD, they say the relationship between a person’s gut health and these variables is extremely complex. . “Someone’s risks can be completely different while in utero or as a child or in adulthood,” Kaplan points out. He gives the example of smoking. It is possible that smoking in adolescence, more so in adulthood, is a higher risk factor for intestinal disorders. Or vice versa. A person’s risk may also depend on how much they smoke, as well as their genetic predisposition to GI disease. “There are so many variables that create too much heterogeneity,” he said. “Say this is a risk factor and it’s not too hard to do.”

With that in mind, Kaplan says people can take steps to reduce their IBD risk. “These are often the things that promote healthy living in general,” he said. “Eating more whole foods, getting regular physical activity, and trying to reduce stress in your life are all on the checklist I make with patients.” For people living in parts of the country where sunlight is sparse, he says taking a vitamin D supplement can be helpful. “If you look at people with IBD, you often see a vitamin D deficiency. This may just be a by-product of the condition — not the cause of it,” he explains. However, he says that supplementing with 1,000 IU a day is a low-risk marker against the gut problems that may be associated with a deficiency.

Read more: Stool transplantation: A new treatment for IBD

The role of external factors such as diet, medications, and pollution in IBD is complex. But medical science is making great strides in looking at the effects of environmental factors. “It was a revolution in the way the field has opened up,” says Mayer.

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