Ulcerative colitis isn’t a common condition, but it still affects plenty of people. Some 1 million people in the U.S. are thought to have this type of inflammatory bowel disease (IBD). It’s three times more common than Crohn’s disease, the other main type of IBD. And experts say the number of UC cases, along with IBD as a whole, seem to be on the rise.
UC happens when your immune system overreacts, causing inflammation and sores in the lining of your large intestine (colon). It’s not clear exactly what causes this process, but scientists think certain things -- like your age, where you live, and your genes -- may make you more prone to UC.
Is Ulcerative Colitis Genetic?
One of the single biggest risk factors for UC and Crohn’s disease is a family history of the disease.
About 10% to 25% of people diagnosed with UC have a parent or sibling with IBD. You’re four to eight times more likely to develop some type of IBD if you have a close relative with the condition.
Researchers have found changes, or variants, in several genes that they think are linked to UC. They theorize that these variants might cause your immune system to overreact to normal bacteria in your gut, or affect the protective barrier in the lining of your intestine.
Do Gender and Age Affect Your Risk of Ulcerative Colitis?
You can get UC at any age. But it most commonly starts when you’re between the ages of 15 and 30. After that, people ages 50-70 are most likely to develop it.
Research done in North America found that men were slightly more likely than women to be affected by UC. Men are also more likely to be diagnosed later in life, in their 50s and 60s.
Diagnoses in people over 65 are rising. Researchers think this is due both to increasing cases of UC and to an aging population. Between 25% and 35% of people with IBD are 60 or older and about 15% of them were diagnosed later in life.
Some research has found that older people are more likely to get surgery for their UC than younger people with the condition. They’re less likely to take immunomodulator medications (those that calm an overactive immune system). This may be because they have other conditions and take other medications that could interact with immunomodulators.
Does Your Race or Ethnicity Increase the Risk?
Caucasian people are more often diagnosed with UC than those with African or Asian ancestry. And the condition is three to six times more common in people of Jewish heritage than in other groups.
But IBD is being diagnosed more often in Black, Asian, and Hispanic people than in previous years. It’s not clear whether this means IBD is becoming more common in these populations, or if it reflects differences in how often doctors are diagnosing it.
Are There Geographic Links to Ulcerative Colitis Incidence?
All types of IBD happen more often in industrialized nations. North America and Northern Europe have the highest rates of UC in particular.
But experts say IBD is increasingly becoming a global disease. Some believe that a Westernized diet or lifestyle may be at least partly responsible for triggering IBD symptoms.
UC is also thought to be more common in cities than in rural areas.
The condition seems to be more common in countries with advanced sanitation systems, which could mean that less exposure to bacteria increases your risk.
Can Medications Raise Your Risk for Developing Ulcerative Colitis?
Taking several courses of antibiotics, especially broad-spectrum ones that act on different types of bacteria, may raise your risk for both UC and Crohn’s. This might be because antibiotics can affect the delicate balance of bacteria in your gut, known as the microbiome.
Some research has suggested that taking birth control pills could raise your risk for UC by 30% if you’re genetically prone to the condition. But we need more studies on this.
If you have UC, your doctor might warn you that taking aspirin or nonsteroidal anti-inflammatory drugs (NSAIDS) like ibuprofen and naproxen could make your symptoms worse. But these medications aren’t thought to raise your risk for UC.
One thing that might lower your risk of developing UC? Having your appendix removed before age 20 because of an inflammation (though this actually raises your odds for Crohn’s disease). It’s not clear why this happens. But scientists theorize that your appendix may have an impact on your immune system.
Does Your Environment Play a Role?
Experts think that, when your genes put you at risk for UC, the condition could be triggered by something in your environment, like bacteria or a virus. The idea is that this trigger activates your immune system, leading to the inflammation of UC. Bowel infections and changes in your gut microbiome are thought to be important triggers for UC.
Studies have also shown that you’re at higher risk for UC when you stop smoking. (Although the dangers of smoking far outweigh this risk.)
While the findings aren’t conclusive, researchers have looked at several other things that might raise your odds of getting UC or make symptoms worse for people who already have it. They include:
- Air pollution
- Diets high in sugar and fat and low in fiber
- Milk consumption
- Low levels of Vitamins A and E