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What Are the Risk Factors for Inflammatory Bowel Disease?

Abdelhakim Elbarsha is a consultant gastroenterologist, endoscopist, and an assistant university professor.

Crohn's disease (left) affects the large intestine differently than ulcerative colitis (right).

Crohn's disease (left) affects the large intestine differently than ulcerative colitis (right).

What Is Inflammatory Bowel Disease?

The term inflammatory bowel disease (IBD) refers to two relatively common digestive disorders: ulcerative colitis and Crohn’s disease. Although they are different in many aspects, including symptoms, behavior, management, and prognosis (long-term outcome), they are still on a spectrum of chronic gut inflammation. This makes it difficult, in some patients to distinguish between the two diseases.

How Common Is Inflammatory Bowel Disease?

According to the CDC epidemiology report for IBD, 5 to 30 out of 100,000 persons are diagnosed with IBD in the United States every year. The estimated number of patients with IBD in the United States is around 60 to 600 per 100,000 persons. IBD is less common in the Far and Middle East, though its incidence is increasing.

What Causes Inflammatory Bowel Disease?

The exact cause of IBD is not clear, although we know that certain environmental and genetic factors play significant roles in the development and progression of the disease. It's not yet known why only some persons develop the disease, while others do not.

What are the risk factors?

What are the risk factors?

What Are the Risk Factors For IBD?

For a particular disease, there may be multiple factors (genetic or environmental), that increase a person's risk of developing the disease in the future. The risk increases with the number of factors present. Some factors are avoidable (i.e. we can reduce our risk by eliminating these factors), but other factors cannot be modified by any means.

1. Age

Most new cases are diagnosed between the ages of 15 and 40. Outside of this range, IBD occurs less frequently

If you are older than 40, your risk will remain lower until you reach the age of 50, when the risk will steadily rise again until it peaks around the age of 60-65 years.

2. Race and Ethnicity

The disease is most common in Jewish populations and less common in other demographics.

This risk may be altered (over time) if you migrate to a geographical area with different (higher or lower) incidence rates of IBD, indicating that there is also a strong environmental influence.

3. Genetics

If you have or had family member with IBD, you are genetically susceptible and at are at higher risk of have the disease in the future. Up to 25 percent of inflammatory bowel disease patients have family members with either ulcerative colitis or Crohn’s disease.

Do you smoke?

Do you smoke?

4. Smoking

Smoking elevates the risk of Crohn’s disease. In patients who already have Crohn’s disease, smoking cessation can significantly decrease disease severity, frequency of flares, and improve the response to treatment.

On the other hand, smoking doesn't increase the risk of ulcerative colitis. In fact, nicotine may even protect against ulcerative colitis by suppressing the immune system (decreasing the inflammatory response). Interestingly, patients with ulcerative colitis who give up smoking may find that their condition actually worsens. However, don't take this as advice to start or keep smoking!

Oatmeal is both high in fiber and known to reduce inflammation and improve cardiovascular health.

Oatmeal is both high in fiber and known to reduce inflammation and improve cardiovascular health.

5. Diet

If you consume foods that are processed, fried, high in fat, or high in sugar, you increase your risk of getting Crohn's disease.

In contrast, if you keep a healthy diet that is high in fiber, you are less likely to develop inflammatory bowel disease.

6. Allergy to Milk

Did you suffer from an allergy to cow's milk protein when you were an infant? If the answer is yes, your risk of getting ulcerative colitis will be higher than those who had no such allergy.

7. Obesity

Obese populations have an increased risk of developing IBD, and in those who already have the disease, obesity can worsen the progression and symptoms.

8. Have You Had Gastroenteritis?

Gastroenteritis is the infection and subsequent inflammation of the intestinal lining. If you have been diagnosed with gastroenteritis in the past—particularly if it was caused by Salmonella or Campylobacter bacteria—you have a higher risk of getting IBD, even 15 years after the episode of gastroenteritis.

9. Have You Had an Appendectomy?

For unknown reasons, the surgical removal of the appendix (appendectomy), may protect you from having ulcerative colitis. This is especially significant if your surgery was done before the age of 20 and if the appendix was obviously inflamed (the appendix can be healthy when the diagnosis is incorrect).

10. Do You Regularly Use Painkillers (Analgesics)?

If you take a non-steroidal anti-inflammatory drug (NSAID) class of painkiller for a pre-existing medical condition, your risk of IBD may be slightly increased. However, it has to be chronic use—for at least 15 days a month—for the risk to be significant. The use of acetaminophen (Paracetamol or Tylenol) doesn't appear to affect the risk of IBD.

11. Do You Use Oral Contraceptives or Hormone Replacements?

Both oral contraceptives and hormone replacement therapies may increase the risk of inflammatory bowel disease.


Having an elevated risk of developing a disease doesn't mean that you will inevitably develop it. You should, however, intervene to modify the risk factors that can be modified in order to lower the risk as much as you can.

As the name suggests, inflammatory bowel disease develops because of increased inflammation in the colon and intestines. The easiest, and often most effective, method of prevention is to change your diet and lifestyle to reduce inflammation.

  • Avoid smoking.
  • Lose excess body weight.
  • Eat a healthy diet: high fiber and low fat. Avoid processed and high-sugar food.
  • Avoid unnecessary use of analgesics.
  • For birth control, use safer methods instead of oral pills.
  • For postmenopausal symptoms, talk to your doctor about using less risky medications than hormonal treatment.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.