Several factors can make diverticulitis worse, from what you eat and how much you move to medications you might already be taking. Red meat, certain pain relievers, smoking, low vitamin D levels, excess belly fat, and a sedentary lifestyle all raise your risk of flares or complications. Some of these are well-established; others may surprise you.
Red Meat Is a Bigger Factor Than You Think
A large, long-running study of men found that those who ate the most red meat had a 58% higher risk of developing diverticulitis compared to those who ate the least. The risk climbed roughly 18% for every additional daily serving. Even one serving per week appeared to increase risk, though the effect leveled off after about six servings per week.
What’s surprising is the type of red meat that matters most. Unprocessed red meat, think steaks, roasts, and hamburger patties, drove the association. Processed red meat like bacon and hot dogs didn’t show a significant independent link after researchers accounted for other factors. Swapping one daily serving of unprocessed red meat for poultry or fish was associated with a 20% lower risk of diverticulitis.
Nuts, Seeds, and Popcorn Are Not the Enemy
For decades, doctors told patients with diverticular disease to avoid nuts, seeds, popcorn, and corn. The theory was that small particles could lodge in the pouches of the colon and trigger inflammation. That advice turned out to be wrong.
An 18-year study following more than 47,000 men found no increased risk of diverticulitis from eating nuts, corn, popcorn, or seeds. In fact, men who ate nuts or popcorn at least twice a week had a lower risk of diverticulitis than men who rarely ate them. Popcorn showed the strongest protective association, with a 28% risk reduction in the highest-intake group. You can eat these foods without worry.
NSAIDs Raise the Risk of Perforation
If you regularly take over-the-counter anti-inflammatory pain relievers like ibuprofen or naproxen, this is worth paying attention to. People with diverticular disease who used NSAIDs for four weeks or longer had roughly three times the risk of a perforated colon compared to those who didn’t take them. Even among all patients with diverticular disease, NSAID users were nearly twice as likely to have complications as non-users.
The concern is that NSAIDs weaken the protective lining of the colon, making already-vulnerable pouches more prone to tearing. If you have diverticular disease and need regular pain relief, it’s worth discussing alternatives with your provider. Acetaminophen doesn’t carry the same colonic risk.
Smoking Significantly Increases Complications
Smoking raises the overall risk of diverticulitis by about 59% compared to never smoking. But the real danger is in how it escalates complications. Men who had ever smoked faced a 2.7-fold increase in developing perforation or abscess compared to nonsmokers. Even former smokers carried elevated risk, though less than current smokers.
Alcohol, by contrast, doesn’t show a clear, statistically significant link to diverticulitis in pooled analyses. Some individual studies have suggested heavy drinking may contribute to complications like bleeding, but the overall evidence is mixed.
Belly Fat Matters More Than Your Weight
BMI alone doesn’t reliably predict who will develop complicated diverticulitis. In one study, patients with complications had an average BMI of 24.1 compared to 23.3 for those with simple diverticulitis, a difference that wasn’t statistically meaningful. But visceral fat, the deep fat packed around your organs, told a different story.
Patients with complicated diverticulitis (perforation, abscess, or severe inflammatory response) had significantly more visceral fat than those with uncomplicated disease: an average of 128.6 square centimeters versus 102.8 square centimeters on imaging. The ratio of visceral fat to the fat just under the skin was also higher. This means you can be at a normal weight and still carry the kind of internal fat that worsens diverticulitis outcomes.
Lack of Vigorous Exercise
Physical activity lowers diverticulitis risk, but not all exercise is equal. In a large study of men, those in the highest activity group had a 25% lower risk of diverticulitis compared to the least active. The benefit came almost entirely from vigorous activity. Non-vigorous exercise like casual walking didn’t show a significant protective effect on its own.
Running stood out as the only individual activity with a statistically significant benefit. Men who ran the equivalent of about three hours per week had a 47% lower risk of diverticulitis compared to non-runners. The proposed mechanisms include faster transit time through the colon, lower internal colon pressure, and reduced systemic inflammation. Men who logged at least three hours of vigorous activity weekly also had a 39% reduction in diverticular bleeding risk.
Low Vitamin D Levels
Vitamin D status appears to play a role in whether diverticular pouches stay quiet or become inflamed. Patients who were hospitalized for diverticulitis had significantly lower pre-diagnostic vitamin D levels (averaging 25.3 ng/mL) compared to patients with diverticulosis who never developed inflammation (29.1 ng/mL). Those in the highest vitamin D group had roughly half the risk of diverticulitis hospitalization compared to those in the lowest group.
The connection was even starker for severe cases. Patients who needed emergency surgery had an average vitamin D level of just 22.7 ng/mL. Vitamin D helps regulate immune responses in the gut lining, and deficiency may allow inflammation to escalate once it starts.
Fiber: Timing Is Everything
Fiber has a complicated relationship with diverticulitis depending on where you are in the cycle. During an active flare, high-fiber foods can irritate an already-inflamed colon. Clinical nutrition guidelines recommend limiting fiber to 10 to 15 grams per day while symptoms are active.
Once the flare resolves, the goal flips. You should gradually reintroduce high-fiber foods one at a time, working toward 30 to 35 grams per day. A high-fiber diet during the maintenance phase helps keep stool soft and moving, which reduces the pressure inside the colon that contributes to new pouches forming and existing ones becoming inflamed. The key word is “gradually.” Adding too much fiber too quickly after a flare can cause gas, bloating, and cramping that mimics a recurrence.
Gut Bacteria Imbalances
The bacterial ecosystem in your colon shifts in ways that appear to drive the progression from harmless diverticulosis to active diverticulitis. Research has consistently found that a family of bacteria called Enterobacteriaceae is the group most associated with disease progression, followed by changes in Bifidobacteria levels. These shifts can promote inflammation in the colon wall, particularly in and around the diverticular pouches.
This is one reason why diet, fiber, and overall gut health matter beyond the mechanical effects. What you eat shapes which bacteria thrive in your colon, and the wrong bacterial balance can tip quiet pouches toward inflammation. Maintaining a varied, fiber-rich diet during remission helps support the microbial diversity that keeps inflammation in check.