Diverticulosis is one of the most common findings in the digestive tract, affecting anywhere from 5% to 45% of people in Western countries depending on age. Under age 40, fewer than 20% of people have diverticula (small pouches that form in the colon wall). By age 60, that number climbs to roughly 60%. If you’ve been told you have diverticulosis after a colonoscopy or CT scan, you’re far from alone.
Prevalence by Age
Age is the single strongest predictor of diverticulosis. The condition is uncommon in young adults but becomes increasingly routine with each passing decade. In one large study of people undergoing screening colonoscopies, about 21% of those in their 50s had incidental diverticulosis, compared to 42% in their 60s and 46% in their 70s. Overall, about 27% of all patients screened had diverticula they didn’t know about.
These numbers have been shifting. Over the past two decades, diverticulosis has become more common in people younger than 50. Researchers attribute this to declining fiber intake, rising obesity rates, and less physical activity in younger populations.
Who Gets It More Often
Men develop diverticulosis at higher rates than women until around age 80, when the gap disappears. In the 40 to 49 age range, women have about 29% lower odds of having diverticula compared to men. That gap narrows gradually: women in their 50s have 21% lower odds, women in their 60s have 19% lower odds, and by age 80 the difference is statistically negligible.
Race and ethnicity also play a role, though the pattern is more complex than simple prevalence numbers suggest. Compared to non-Hispanic white individuals, Black individuals have about 20% lower odds of diverticulosis overall, Hispanic individuals about 7% lower odds, and Asian/Pacific Islanders about 62% lower odds. However, these numbers reflect left-sided diverticulosis, which is the dominant pattern in Western countries. Black individuals actually have 53% higher odds of right-sided diverticula, and Asian/Pacific Islanders have more than three times the odds of right-sided diverticulosis compared to white individuals.
Left-Sided vs. Right-Sided Diverticula
Where diverticula form in your colon varies significantly by geography and ancestry. In Western and developed nations, diverticula overwhelmingly appear on the left side of the colon, particularly in the sigmoid colon near the bottom. These left-sided pouches tend to develop later in life as the colon wall weakens with age. They’re “false” diverticula, meaning only the inner lining of the colon pushes through the muscle wall.
In Asian countries like Korea and Japan, the pattern flips. Diverticulosis is predominantly right-sided, with an overall prevalence around 13% to 25%. Right-sided diverticula are structurally different. They’re “true” diverticula involving all layers of the colon wall, and they don’t appear to be linked to aging in the same way. This distinction matters because left-sided and right-sided diverticulosis can behave differently when complications arise.
Most People Never Develop Problems
The most reassuring number about diverticulosis is how rarely it causes trouble. Older medical literature estimated that 10% to 25% of people with diverticula would eventually develop diverticulitis, the painful inflammation or infection of those pouches. More recent research puts the actual progression rate at closer to 5%. That means roughly 95 out of 100 people with diverticulosis will never experience a significant complication from it.
This is worth emphasizing because diverticulosis is frequently discovered incidentally during a colonoscopy or imaging done for an unrelated reason. In the screening colonoscopy study, 67% of the diverticula found were in the left colon, about 6% were limited to the right colon, and 23% appeared on both sides. For the vast majority of these patients, the finding required no treatment or follow-up beyond general healthy habits.
Risk Factors You Can Influence
Fiber intake has the strongest and most consistent relationship with diverticular disease risk. A meta-analysis of prospective studies found that for every additional 10 grams of fiber consumed per day, the risk of diverticular disease dropped by 26%. Compared to people eating a low-fiber diet (around 7.5 grams daily), those consuming 30 grams per day had a 41% reduction in risk, and those hitting 40 grams per day had a 58% reduction. For reference, most Americans eat about 15 grams of fiber daily, well below the recommended 25 to 30 grams.
Body weight and exercise also matter, particularly for more serious forms of the disease. A large prospective study of women found that being overweight (BMI 25 to 30) increased the risk of diverticular disease requiring hospitalization by 29%, while obesity (BMI 30 or above) increased it by 33%. Obese women had double the risk of complicated disease specifically. Women who exercised 30 minutes or less per day had a 42% higher risk compared to those who were more active.
The Scale of the Problem
Even though most diverticulosis stays silent, the sheer number of people who have it means diverticular disease generates an enormous amount of healthcare activity. In the United States, roughly 815,000 hospitalizations and 3.2 million outpatient visits per year are attributed to diverticular disease. The aggregate cost of those hospitalizations alone exceeded $3 billion as of 2008, with an average cost per hospital stay of about $9,600. Total direct and indirect costs, including outpatient care and lost productivity, reached $2.5 billion annually even a decade earlier, and have only grown since.
These numbers reflect the small percentage of diverticulosis cases that do progress to diverticulitis or complications like bleeding. They underscore why the modifiable risk factors, particularly fiber intake, weight management, and regular physical activity, carry real public health significance despite the low individual risk of any single person’s diverticula causing problems.