Let's Talk About the Causes of Ulcerative Colitis

Number one and most important: It's not your fault you were diagnosed with UC. We'll help you understand what factors do play a part so you can get on with what matters: feeling better.

by Lara DeSanto Health Writer

If you've been diagnosed with ulcerative colitis (UC), some of the first questions you probably have are "Why this and why now?" And maybe also: "So will I just be spending the rest of my life in search of the nearest bathroom?" (Short answer: Nope.) Here's what we also know: Nothing you did—or didn't do—caused you to get UC. In fact, there is no single cause of this type of inflammatory bowel disease (IBD); everything from your genetics and family history to potential environmental factors can increase your risk and flip that UC switch. We're here to help you sort it all out so you can find the answers you need.

UC Causes

Our Pro Panel

We went to some of the nation’s top UC experts to bring you the most scientific and up-to-date information possible.

Aline J Charabaty Pishvaian

Aline Charabaty Pishvaian, M.D.

Director of the Inflammatory Bowel Disease Center

Sibley Memorial Hospital

Washington, D.C.

Jason Schairer MD

Jason Schairer, M.D.

Senior Staff Gastroenterologist

Henry Ford Inflammatory Bowel Disease Center


Neilanjan Nandi

Neilanjan Nandi, M.D.

Director of the Inflammatory Bowel Disease Center

Drexel University School of Medicine


UC Causes
Frequently Asked Questions
My parent/sibling has UC. What does that mean for my risk?

Having a sibling or parent who has UC significantly raises your risk of developing UC yourself. In fact, about 10% to 25% of people with UC have a sibling or parent with some form of IBD, whether it be UC or Crohn's disease.

Did I cause my UC?

There's nothing you did or didn't do that caused you to develop UC. The cause of UC is complex and depends on many factors, from your genes to your environment.

Is ulcerative colitis an autoimmune disease?

Some researchers theorize that UC is an autoimmune disease because a flaw in your immune system may cause it to mistakenly attack healthy tissue in the large intestine. There’s not yet a full consensus, so we can't say definitively that UC is in fact a true autoimmune disease.

I'm worried about getting UC. Is there anything I can do to prevent it?

Unfortunately, there's nothing you can do to 100% guarantee you won't develop UC at some point. That said, it's always wise to practice a healthy lifestyle, including eating a healthy diet, exercising regularly, and prioritizing your mental health.

What Exactly Is UC, Again?

Ulcerative colitis is a condition that causes chronic inflammation in the colon and rectum.

As you might expect, inflammation in the organs that are supposed to manage your body's waste products can lead to some pretty uncomfortable and embarrassing problems involving poop. And gas. And more poop.

Your intestines are the organs that manage both your body’s waste but more importantly absorption of nutrients.

But UC doesn't only cause digestive issues. The inflammation it causes is body-wide, which means it can trigger symptoms like joint pain, extreme fatigue, and more—not to mention the stress and anxiety that can come with dealing with a serious chronic disease.

So yes, it's a lot.

Get All of Your Ulcerative Colitis Questions Answered

What Are the Causes of UC?

In North America, there are about a million people living with ulcerative colitis. But what caused you to develop UC in the first place?

There's no easy answer to this question because, according to scientists, there are multiple factors that work together to determine whether a person will get UC. You may hear these referred to as risk factors.

One simple one is your age: While UC can strike at any time in life, it usually appears in people between the ages of 15 and 30. People over 60 are also more likely to develop UC.

Currently, experts believe genetics influence about 5% to 30% of UC, while the rest is likely some combination of stuff that you're exposed to through, you know, living your life (aka "environmental factors"). Take a look:


Your genes play a significant role in whether you will develop UC. First degree relatives of individuals with IBD have a 2-5% lifetime risk of developing UC. It's clear there's something that we inherit from our parents that makes us more likely to develop the disease.

In fact, scientists have identified more than 200 genes that impact whether someone gets IBD. But how exactly these genes work isn't yet fully clear.

What we do know is that some of the genetic variations scientists have identified relate to the intestines' protective mechanisms.

Basically, healthy intestines block bacteria and other invaders from entering the body’s tissues. It’s possible that in people with IBD, this barrier is weakened. When the immune system notices these cracks in the pipe, it may break out the blowtorches of inflammation to repair them when perhaps a simple sealant would do.

The result? A scorched-earth campaign inside your colon.

Race and ethnicity may increase your risk, too: While UC affects people of all races and ethnicities, it is more common in white people and in people of Ashkenazi Jewish descent.

Besides genetics, the “rest” of the contributions to someone getting UC besides environmental, is also the gut flora or what we call microbiota.

An Immune-System Flaw

Of course there's glitch in your immune system when it jumps to the biggest possible reaction first.

But in some people with UC, there could be a more subtle communication error: It's possible that genetics may program your immune system to respond in an abnormal way to environmental triggers, like food, bacteria in your gut's microbiome, and more.

Other Potential Environmental Factors

Spoiler alert: While there is some research linking the following factors to IBD, the findings are inconsistent, and evidence isn't strong enough to make any claims of a cause-and-effect relationship. More studies are 100% needed. That said, these factors are possibly part of the UC picture and worth knowing about:

  • Certain infections. Some theories suggest that particular pathogens, including bacteria like Salmonella or Campylobacter, may increase your risk of developing IBD, possibly by permanently changing the makeup of your gut bacteria, according to a review in Frontiers in Immunology.

  • Nonsteroidal ANTI-inflammatory. Some studies have found the use of certain medications is associated with a UC diagnosis. For example, one study in Gastroenterology found that nonsteroidal anti-inflammatory drugs (NSAIDs) were positively linked to UC—perhaps because of the damage these drugs can cause to the lining of the gut, they can mimic ulcerative colitis.

  • High-fat diet. While you may find that certain foods you eat trigger your symptoms more than others, there's no diet that specifically causes UC to develop. But there is some research that suggests that eating a lot of saturated fat can increase your risk, perhaps because fatty foods fuel inflammation. It's also interesting to note that UC is most common in North America and in Western Europe—so some theorize that there may be something about the typical western diet that could contribute to UC development. Typically, experts recommend people follow a Mediterranean, plant-based diet for optimal health.

  • Stress. It's clear that stress can make UC symptoms worse, but could it play a role in causing the disease in the first place? Some research, like this study in the journal Gut, suggests that chronic stress in your daily life can affect your immune system’s ability to function, potentially increasing your risk of IBD.

Is There Anything You Can Do to Prevent UC?

Unfortunately, there's currently nothing you can do to guarantee that you won't one day develop UC. That said, it's always wise to lead a healthy lifestyle to reduce your risk of health problems overall—including complications of UC if you've already been diagnosed. Some healthy habits to adopt include:

  • Eat a healthy diet.

  • Get regular exercise.

  • Prioritize your emotional and mental health.

  • Follow your treatment plan for UC or any other chronic conditions, including taking meds as prescribed and keeping up with your scheduled checkups with your health care team.

Some studies have shown that having had an appendectomy in early childhood could protect against developing UC—but again, more research needs to be done to fully understand this potential link.

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at WTOP.com.