Diverticulosis is a common condition, especially in older adults, in which small pockets or sacs called diverticula form and push outward through weak spots in the colon.

Half of Americans over the age of 60 have diverticulosis, making it the most common finding during a routine colonoscopy.

A 2023 analysis found that the incidence of diverticulosis in the U.S. has increased and the average age of diagnosis has decreased. Researchers blame these trends on poor dietary habits and the obesity epidemic that has worsened in the last two decades.

What Is Diverticulitis?

Fortunately, most people who have this condition will never develop symptoms. However, an estimated 5% of those with diverticulosis will experience diverticulitis. This occurs when the pockets become inflamed or infected, which can be extremely painful and sometimes requires surgery.

Recommendations for preventing diverticulitis and managing diverticulitis flare-ups have changed throughout the years. Trouble is, some old advice is still floating around.

Here’s what you should know about what to eat and avoid to help prevent and treat diverticulitis.

Risk Factors for Diverticulitis 

The American Gastroenterological Association recommends a high quality, high-fiber diet that’s rich in fiber from fruits, vegetables, whole grains and legumes and low in red meat and sweets since this dietary pattern is shown to decrease diverticulitis risk, says Boston-based registered dietitian Kate Scarlata, a digestive health expert and co-author of “Mind Your Gut.”

Dr. Anne Peery, lead author of AGA’s Clinical Practice Update Expert Review on diverticulitis and an associate professor of medicine at the University of North Carolina School of Medicine, reinforces the important role of fiber. However, she also notes that diverticulitis is not the result of constipation, which was previously believed.

“Instead, we have good evidence that genes contribute to the risk and that several modifiable risk factors are associated with an increased risk, such smoking, obesity, physical inactivity, nonsteroidal anti-inflammatory drugs or NSAIDs (like aspirin and ibuprofen), and a low quality diet,” she says.

Foods to Eat to Prevent Diverticulitis 

Eating a high-fiber diet is important for many reasons, including to lower the risk of diverticulitis.

An analysis from the Nurses’ Health Study found that women with the highest dietary fiber consumption had the lowest incidence of diverticulitis. The study found that the consumption of whole fruits (particularly apple, pear and prune) and cereal fibers was linked to lower incidence of diverticulitis.

Similar studies of men from the Health Professionals Follow-Up Study demonstrated that a diet rich in fruits, vegetables, whole grains, legumes, poultry and fish was associated with a lower incidence of diverticulitis compared to a standard American diet, which generally contains more refined grains and processed meat and fewer fruits and vegetables.

High-fiber foods to eat to help prevent diverticulitis include:

Foods to Eat During a Diverticulitis Flare-Up

It’s important to remember that what you eat to prevent diverticulitis is quite different from what you should eat during a diverticulitis flare-up.

A clear liquid diet used to be recommended during a diverticulitis flare-up, but now a more personalized approach is taken. One small study suggested that a liquid diet is not necessary in the acute phase of diverticulitis, although many patients report greater comfort on a clear liquid diet.

If recommended for a short period, a clear liquid diet includes:

Restricting fiber intake during an episode has long been recommended; however, there is little evidence to support this practice, and this advice has come under scrutiny in recent years. A systematic review of five studies suggests little differences in clinical outcomes based on diet during treatment of acute diverticulitis.

“A low-fiber diet was initially proposed to manage diverticulitis. However, this recommendation was not based on scientific study,” says Scarlata.

Yet, because inflammation in the colon can make digestion uncomfortable, some people may find that it helps to avoid certain foods.

“We often advise patients with diverticulitis to consume a liquid or low-residue diet while they recover,” says Peery, who manages patients with diverticular disease. “This is primarily for patient comfort.”

The AGA guidelines recommend that this diet intervention be limited to a few days before the patient advances to a high-fiber, well-balanced diet to prevent future flares.

Low-fiber or low-residue foods include:

Foods to Avoid on a Diverticulitis Diet 

No specific foods are known to trigger diverticulitis attacks. However, research suggests a typical American diet high in fat and sugar and low in fiber may increase your risk. To mediate your risk, reduce your intake of these foods:

For years, people with diverticulosis were advised to stay away from popcorn, corn, nuts and seeds, even the seeds in certain fruits and vegetables like strawberries, raspberries, tomatoes and cucumbers.
It was believed that little bits of food could get stuck in those pockets and cause inflammation or infection, leading to diverticulitis. Yet this theory has never been proven, and research shows no link.

This is another example of how the advice on managing diverticulitis has changed.

Scarlata says you do not have to worry about eating popcorn, corn, nuts and seeds since evidence does not show a higher risk of diverticulitis in people who eat those foods compared with people who don’t. “We do not restrict these foods in clinical practice at this time,” she says.

Not only is it not necessary to avoid popcorn, corn, nuts and seeds, there may be good reasons to eat these foods. A large, 18-year study of men with diverticular disease found that nut, corn and popcorn consumption was associated with a lower risk of diverticulitis, suggesting that these nutritious, high-fiber foods could be protective.

A Low FODMAP Diet for Diverticulitis 

Certain types of carbohydrates known as FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides and polyols) have been suggested to be a culprit in diverticulitis.

High FODMAP foods like garlic, onion, dairy, cabbage and beans produce gas and pull water into the gut, which some researchers suggest could stretch the colon and increase the risk for diverticulitis onset.

Scarlata describes FODMAPs as “fast food for our gut microbiota,” although she says this theory in patients with diverticulitis has not been studied in a research setting.

While a low FODMAP diet may be helpful for select patients with irritable bowel syndrome, there is no evidence for a low FODMAP diet in diverticulitis patients, says Peery.

“Diverticulitis is not triggered by high pressure in the colon,” she says.

New Approach to Diverticulitis  

In a recent review of the controversies in diverticulitis, researchers at Oregon Health and Science University in Portland outlined multiple changes in the treatment and prevention of this common gastrointestinal disease.

For instance, antibiotics should be used selectively rather than routinely in patients with acute uncomplicated diverticulitis. Additionally, little evidence supports the use of probiotics to improve symptoms or the reoccurrence of diverticulitis.

They conclude that the landscape of diverticulitis is ever-changing and that it may be warranted to be less aggressive in patient care.

It’s also not all about what you eat.

“I see many patients in clinic who blame themselves for episodes of diverticulitis,” says Peery. “They come to see me seeking ‘the right diet’ to prevent episodes and are sometime afraid to eat.”

The contribution of diet to diverticulitis risk is only about 10% to 15%, she says. It’s important for patients to appreciate that diverticulitis is a complex condition with multiple risk factors, including genetics. Family and twin studies suggest that about half of diverticular disease is linked to genetic factors.

Risks of a Diverticulitis Diet

The nutrition therapy for diverticulitis has few risks unless you continue on a clear liquid diet for an extended period of time. A liquid diet does not provide adequate nourishment and it could lead to weakness or other complications.

That’s why the approach for managing diverticulitis has changed in recent years. If you have a flare up, your doctor may recommend a liquid diet for a day or two and then will transition you back to a high-fiber, balanced diet as soon as you can tolerate it.