Are You at Risk?

Since the mid 20th century, diagnoses of ulcerative colitis and Crohn's disease increased dramatically in Canada. In 2018, over 270,000 Canadians are believed to be living with IBD. By 2030, that number is expected to rise to 403,000 Canadians (1 in 100 people).

IBD is more common in developed countries, urban areas and temperate climates.

Crohn’s and colitis can be diagnosed at any age, but people are more frequently diagnosed before the age of 30. Crohn’s disease has almost doubled in Canadian children under 10 since 1995.

Males and females are equally affected by Crohn's and colitis. 

Crohn’s and colitis can affect any race or ethnic group however, people of Jewish Ashkenazi (European) descent and some South Asian immigrant populations in Canada have higher rates of inflammatory bowel disease.

The cause of IBD is very complex and is believed to involve a genetic tendency (predisposition) and a trigger in the environment that are combined to set off inflammation in the gut. Instead of being dampened down, the immune system then continues to run amok. The chronic (lifelong) process that results can manifest as either Crohn’s disease or ulcerative colitis.

Below you will find more information about genetic, microbiotic and environmental factors that may contribute to the development of IBD:


The genetic impact on IBD has been long recognized. Early studies on twins show that identical twins are more likely to both have Crohn's disease or ulcerative colitis as compared to fraternal twins. 

Genetic analyses of vast regions of the human genome have idenditifed more than 200 genetic mutations associated with the development of Crohn's disease and ulcerative colitis.

In many cases, these genetic mutations linked to IBD are also shared with other immune-mediated disorders including type 1 diabetes, celiac disease, rheumatoid arthritis, ankylosing spondylitis, and psoroasis. 

Identifying the proteins made by these genetic markers paints a clear picture of the critical role between the immune response in the bowel and the 100 trillion microbes living there. 


It is possible that changes in the gut microbiome trigger immune responses that cause abnormal inflammation. The gut microbiome is a community of microorganisms including bacteria, fungi, and viruses living in the environment of the intestines. 

Since people with IBD are normally studied after the disease has manifested, it is still not clear as to whether the changes in the microbiome and immune response are a cause or effect of the disease. 

It has been suggested that the use of antibiotics, which can alter the gut microbiome even long after antibiotics have been discontinued, may trigger IBD to develop. 

Much more work is required to understand the exact causes of the microbiome changes and the changes that are most relevant to triggering disease so that treatments be developed to prevent or reverse IBD. 

Environmental Exposures 

There have been a number of research studies that have identified environmental factors that are critical in triggering the development of IBD. These environmental determinates include both risk and protective factors that are described in more detail below.


Risk Factors

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Current smoker

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Former smoker

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Enteric Infection

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Pro-inflammatory Foods

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Air Pollution

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Non-steroidal Anti-inflammatories

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Migration to Higher Prevalence Area

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Hormonal Medication

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Stress and Depression

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Protective Factors

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Never smoked

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H. Pylori (Bacteria infection)

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Anti-inflammatory Foods

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Vitamin D

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Had Pets as a Child

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Living in a Rural Area

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Physical Activity

Image reference. Impact of inflammatory bowel disease in Canada. 2018.

Hygiene Hypothesis

It has been suggested that children growing up in relatively sterile envrionments - without adequate exposure to microbes - do not prepare their immune system for handling microorganisms. They then develop an abnormal immune response that attacks their organs later in life when exposed to harmful microorganisms. 

Research evidence that supports this hypothesis show that Crohn's disease and ulcerative colitis are less likely to occur in individuals who: live with pets in childhood; are raised on a farm or rural region; have a larger family; or drink unpasteurized milk. 

Recent studies have also shown that susceptibility to IBD may be due to early-life exposures that change the composition of the intestinal microbiome, including loss of friendly microorganisms that could benefit the immune system. IBD is more likely to develop in those who were exposed to antibiotics within the first year of life and also in those who were not breastfed. Antibiotics and breastfeeding strongly influence the diversity of the microbiome in children

Individuals with a history of infectious gastroenteritis are more likely to be diagnosed with Crohn's disease or ulcerative colitis, especially among childhood-onset of IBD.


Dietary factors may have a strong influence on the intestinal microbiome. Studies suggest that a western diet, one with higher consumption of fats and refined sugars, and reduced consumption of dietary fibre, changes our gut's microbiome. 

Processed foods and pervasive fast food popular in western diet may also be contributors to developing IBD. The association between fast food consumption and IBD may be direct via exposure to fatty foods or food additives, or indirect via lifestyle factors such as reduced levels of physical activities. 

Other Environmental Determinates

Several other environmental determinates may influence the development of IBD among Canadians including: 

  • Cigarette smoking increases the risk of developing Crohn's disease in adults. However, adults who quit smoking are at an increased risk of ulcerative colitis. 
  • Oral contraceptives increase the risk of Crohn's disease, particularly among women who smoke. 
  • Non-steroidal anti-inflammatory drugs, such as ibuprofen and aspirin, may also trigger IBD. 
  • Appendicitis diagnosed before the age of ten years protects against ulcerative colitis. 
  • A lack of vitamin D from reduced sun exposure may increase the risk of developing IBD. Vitamin D is important in regulating the immune system and its deficience has been associated with an increased risk of IBD.
  • Air pollution may increase risk of developing Crohn's disease in children and young adults as it alters the intestinal microbiome.

Finding the cause of Crohn's and Colitis

Undestanding the biology behind IBD is critical in developing new strategies to improve quality of life for people living with the disease including: enhancing treatment approaches, exploring possibilities in curing the disease, and identifying avenues for prevention. 

A number of research projects funded by Crohn’s and Colitis Canada are looking at the causes of these diseases. Visit our Funded Research page to find out more.

The Crohn’s and Colitis Canada Genetic, Environmental, Microbial (GEM) Project is a global research study that looks to uncover possible triggers of Crohn’s disease. The more we know about the possible causes of Crohn’s, the closer we get not only to a cure, but also to the ability to prevent the disease from taking hold in the first place. Visit The GEM Project page to learn more. 

Have you been recently DIAGNOSED with Crohn's or colitis?

If you have been recently diagnosed with Crohn's or colitis, visit our Newly Diagnosed page for more information and resources. 

strengthen your knowledge of living with crohn's and colitis

Visit the Living with Crohn's and Colitis section of our website to learn about diet and nutrition in IBD, treatment options, symptom management and other essential information.  

find a community near you

Your local chapter of Crohn’s and Colitis Canada is a powerhouse of health information and support. Through education, presentation and discussion, people can find resources to help them cope with their Crohn’s, and meet others who are living with Crohn’s or colitis.

Visit our Find My Community page to look up the chapter closest to you. It’s in your best interest to get active and informed!

  • Canada has among the highest incidence rates of Crohn's and colitis in the world.
  • 1 in 140 Canadians lives with Crohn’s or colitis.
  • Families new to Canada are developing these diseases for the first time.
  • Incidence of Crohn’s in Canadian kids under 10 has doubled since 1995.
  • People are most commonly diagnosed before age 30.

Other Areas of Interest