What Causes Diverticulitis? 10 Things GI Docs Wish You Knew

Updated: Jun. 30, 2021

If you have ever been sidelined by diverticulitis, you know that it's excruciating. To keep this gastrointestinal condition from coming back, start by understanding what causes diverticulitis.

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What exactly is diverticulitis?

To fully understand what causes diverticulitis, you must take a few steps backward. Diverticula are small pockets that form in the colon. Not everyone develops these pockets, but they are pretty common, especially after age 40. They rarely cause issues—unless one of the pockets become inflamed or infected. “This is what we would call diverticulitis,” says Arun Swaminath, MD, director of the Inflammatory Bowel Disease Program at Lenox Hill Hospital in New York City. “With diverticulitis, comes pain in the lower abdomen and fever,” he says. There may be other symptoms of diverticulitis too. So the question really becomes what causes diverticulitis?

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Don’t worry about nuts and seeds

Popcorn lovers, rejoice! Nuts and seeds likely do not cause diverticulitis, despite what people believe. This is a huge game-changer as doctors have , in the past, advised anyone with a history of diverticulitis to refrain from eating nuts, seeds, and popcorn. “We used to think that seeds or popcorn got stuck in these pockets and blocked them resulting in inflammation and infection,” Dr. Swaminath says. As it turns out, no surgeon has ever found seeds or nuts lodged in one of these pouches. This is great news as nuts are among the best disease fighters that we have in our pantries.

Fermented food great for gut health--glass bowls of kimchi, red beets, apple cider vinegar, coconut milk yogurt, cucumber pickles, sauerkraut

A faulty gut microbiome

Diverticulitis or its predecessor diverticulosis may link back to alterations in the bacterial balance in the gut (aka the microbiome), says Will Bulsiewicz, MD, a gastroenterologist in Mount Pleasant, SC. “The human colon is the densest concentration of bacteria on the planet,” he says. “When you are fiber-deprived, you alter the patterns of bacteria in the gut, and the bad bacteria can outnumber the good,” he says. But prebiotics can set things straight. Probiotics help restore the balance of good and bad bacteria in the gut, and prebiotics are precursors to probiotics. “Most prebiotics are fiber,” he says. “Eating more fiber is the corrective factor.” Glucomannan is a water-soluble fiber supplement that is also a prebiotic, which are two of the many reasons people are going crazy for glucomannan.

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Your diet lacks fruit and vegetable fiber

There are some other reasons why low fiber diets may increase the risk of diverticulosis and diverticulitis. The fiber connection may also be part mechanical, adds Dr. Swaminath. “Fiber bulks up the stool, and it takes less pressure to get a bulky stool out than an under-fibered, dry stool,” he says. “The pressure or contraction of the colon may cause these pockets to form, and if something is stuck in the colon, it can become infected,” he says. “Infection is more likely to occur in areas where there is already vulnerability such as diverticula.” Reverse this by adding more fiber-rich foods including fruits and vegetables to your diet. Women should aim for at least 25 grams of fiber per day, while men should aim for at least 38 grams (or 21 and 30 grams daily, respectively, for those older than 50), according to the Academy of Nutrition and Dietetics. Here are 30 expert-approved ways to sneak more fiber into your diet without trying.

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Your genes

If your mom or dad had diverticulitis, it doesn’t mean you will too, but there is a genetic component, says Dr. Bulsiewicz. “We do see this in families, but that does not mean you are predestined,” he says. “If diverticulitis runs in your family, be more conscious about consuming enough fiber.” Check out these other benefits to eating more fiber—starting with weight loss and a decreased risk of type 2 diabetes.

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You love processed foods and red meat

What causes diverticulitis can vary depending on your diet. Processed foods contain chemicals and preservatives that may harm your gut microbiome and increase your risk for diverticulitis, says Dr. Bulsiewicz. “We know that colon cancer risk is associated with eating too many processed meats, and the root cause is alterations in bacteria in the gut so this may also play a role in causing diverticulitis. ” Your best bet is to avoid or limit processed foods and red meat in favor of a plant-based diet. Meat, in general, is devoid of fiber so a high-meat diet isn’t recommended for people with diverticulitis. These 11 baby steps will ease you into a healthful plant-based diet.

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Your weight

Add diverticulitis to the list of diseases and conditions that being overweight can make worse. New research shows that obese individuals are actually more likely to develop recurrent diverticulitis and need surgery to treat it, according to a study published in Diseases of the Colon & Rectum. One potential reason for the connection may be the increased levels of inflammation common to being overweight or obese. If you’re looking to shed pounds, here’s the best diet for weight loss.

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Your smoking status

The same study in Diseases of the Colon & Rectum showed that smokers are more likely to experience repeated bouts of diverticulitis and may need surgery to treat it. Doctors are unsure why smoking heightens the risk, but “patients with modifiable risk factors such as smoking and obesity can be counseled because this may reduce the risk of recurrent acute diverticulitis,” the study authors said in their report. Here are the 23 best ways to kick the habit for good.

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Your chronic pain meds

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can alleviate pain, but they may also leave you vulnerable to diverticulosis and diverticulitis, according to the American Society of Colon and Rectal Surgeons. These meds are harsh on the stomach and can increase the chances of gastrointestinal bleeding and ulcers, and they may trigger diverticulitis flare-ups. Here are 10 signs of an ulcer that you should never ignore.

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Your overindulgence in alcohol

Excessive consumption of alcohol may double or triple your risk of diverticulitis, according to the American Society of Colon and Rectal Surgeons. While experts aren’t sure exactly why the two are linked, one theory is that drinking too much alcohol may make the colon more vulnerable to both diverticula and diverticulitis. Here’s a guide to the safest amount of alcohol to drink.

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Your age and gender

Younger patients and women are more likely to develop recurrent diverticulitis and require surgery, according to a study published in Diseases of the Colon & Rectum. Which is why it’s rarely a bad idea to increase the amount of fiber in your diet. However, for most people, a seven- to 14-day course of antibiotics usually clears up the infection for good, Dr. Swaminath says.