It’s not totally clear what causes diverticulitis and why some people get it while others don’t. Doctors and researchers believe environmental factors like diet and lifestyle play a major role, though, as well as advancing age and genetics. In particular, diverticular diseases are more common among older people and tend to run in families.

Risk Factors

Leading risk factors for diverticulitis and diverticular disease in general include:

  • Poor diet, especially a diet that is low in fiber
  • Advancing age
  • Family history
  • Physical inactivity
  • Smoking
  • Overweight and obesity
  • Abnormal bacteria (microbiome) in the gut and colon (e.g., either not enough healthy bacteria, too many unhealthy bacteria, or both)
  • Long-term use of certain medications like nonsteroidal anti-inflammatory drugs (NSAIDs) and steroids


What is the main cause of diverticulosis?

Doctors believe a main cause of diverticulosis (which sometimes develops into diverticulitis) is a low-fiber diet

Fiber is a nutrient found in plant foods like vegetables, fruits, nuts, seeds, legumes, and whole grains. Fiber is important for gut and digestive health as it helps keep stool soft and regular. If a person doesn’t eat enough fiber, their stool can become hard, which may lead to constipation and increased pressure in the colon. This increase in pressure can force weak areas along the walls of the colon to bulge outward, therefore leading to diverticula. 

Only five percent of Americans get enough fiber in their diet. How much do most people need? Adults need around 25 to 30 grams of fiber per day, according to the Food and Drug Administration (FDA).

What are the trigger foods for diverticulitis?

According to the National Institutes of Health (NIH), people with diverticulitis don’t necessarily need to avoid or cut out specific foods. But many people with diverticulitis find that certain foods seem to trigger or worsen their symptoms and therefore choose to avoid eating them. These foods may include:

  • Dairy (especially full-fat dairy)
  • Fermented foods
  • Alcohol
  • Refined sugar 
  • Fried or processed foods, including refined grains (like white bread and pasta)
  • Red and processed meats 

Some people with diverticulitis also choose to avoid high-fiber foods while they are experiencing a flare-up in their symptoms, even though such foods are generally considered healthy and beneficial for people with this condition. The reason is that increased fiber can promote peristalsis (colon contractions that help form and move stool), which can exacerbate pain for someone having an acute bout of diverticulitis.

That said, every person is different. The NIH and other experts encourage people with diverticulitis to talk to their doctors about what kind of diet is best for their needs. 

Can diverticulitis be brought on by stress?

It is not completely clear how and if stress is associated with diverticulitis, or if one condition causes the other. It could be a combination of both. Either way, research shows that managing stress can improve both physical and mental well-being, especially in people with chronic health conditions. 

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.

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