If you've ever experienced diverticulitis, you know how disruptive a flare-up can be. That dull ache in your abdomen that worsens with meals. Or perhaps a sharp, unsettling pain that intensifies with even the slightest movement.
"Diverticulitis begins as a condition called diverticulosis, which happens when sac-like protrusions, also referred to as pouches, form in the wall of the colon," explains Dr. Christina Warner, a colorectal surgeon at Houston Methodist. "Diverticulosis by itself doesn't cause symptoms or require treatment. In fact, most people don't even know they have it."
The condition is typically discovered incidentally during a routine colonoscopy — unless one of the pouches becomes inflamed or infected, causing diverticulitis. (Related: How to Relieve Diverticulitis Pain Fast)
And when a diverticulitis flare-up hits, one of the first things you probably ask yourself is: Was it something I ate? It's a reasonable question if your goal is to avoid future attack.
What foods trigger diverticulitis?
While age, genetics and lifestyle behaviors are known to contribute to the development of diverticulosis, Dr. Warner says that what leads to diverticulitis is still somewhat murky. Diet likely plays a large role, though not always in the way people think.
"Many people who've experienced diverticulitis before will say they already know to avoid foods like nuts, seeds, corn, tomatoes, cucumbers, popcorn, peanuts and almonds," Dr. Warner says. "This comes from an old theory that small food particles can get trapped in these pouches, leading to problems. But there's actually no solid evidence to support that claim."
Instead, a low-fiber diet is the more likely culprit of a diverticulitis flare-up. Without enough fiber, the colon struggles to move waste efficiently, causing less frequent bowel movements. This, in turn, makes the formation of small, hard pieces of stool likely. (Related: 7 Benefits of Fiber That Should Convince You to Eat Enough of It)
"You can imagine what might happen if a hard piece of stool traveling through the colon were to get stuck in one of these pouches," says Dr. Warner. "Ventilation becomes blocked, causing mucus and air to build up and eventually leading to inflammation, infection or, in more severe cases, even perforation of the colon lining."
Emerging research also suggests that the gut microbiome — which is heavily influenced by your diet — could also play a role in the likelihood of developing diverticulitis. A poor microbiome may make it more likely to experience flare-ups, but more studies are still needed. (Related: The Signs of an Unhealthy Gut & How to Improve It)
What to eat (and what to avoid) when you have diverticulitis?
There's no one-size-fits-all diverticulitis diet, but certain eating strategies can help manage most flare-ups.
"Your aim is to reduce the strain on your colon and minimize inflammation," explains Dr. Warner. "During an attack, we often recommend a liquid diet — or a soft-food diet at the very least. As symptoms are improving, low-fiber foods can slowly be reintroduced."
Limiting gut irritants is another way to help your colon recover. Those include:
- Caffeine
- Alcohol
- Carbonated beverages
- Dairy, if lactose intolerant
- Fatty or spicy foods
- Red meat
- Processed meat
- Ultra-processed foods
"A more simplified diet means your colon doesn't have to work as hard, so it can heal," adds Dr. Warner. After a flare-up resolves, prevention becomes the focus and that's where a high-fiber diet becomes key.
How to prevent diverticulitis
Once you're feeling better Dr. Warner recommends taking steps to reduce the likelihood of a future diverticulitis attack.
"A high-fiber diet and adequate fluid intake are key to keeping things moving efficiently through the colon, reducing the risk of small, hard pieces of stool developing," says Dr. Warner.
This means eating plenty of vegetables, fruits, whole grains, beans and legumes. Cutting back on red meat and processed meat can make a long-term difference, too.
"Beef, pork and lamb can all be pro-inflammatory," adds Dr. Warner. "And processed meats — jerky, sausage, bacon, hot dogs, brisket, smoked turkey and even lunch meats, like ham — contain preservatives that can also contribute to inflammation in the colon."
(Related: The Keys to Following an Anti-Inflammatory Diet)
Finally, she adds that lifestyle behaviors play a role in preventing diverticulitis, too.
"Smoking is linked to a higher risk of recurrence, so quitting can make a big difference," Dr. Warner adds. "Staying active and losing weight can also help prevent a future flare-up. If you need help implementing any of these changes, visiting your primary care provider is a good first step."
