If you’ve had a routine colonoscopy, there is a good chance you were told afterwards that you have diverticulosis, a condition characterized by small pouches (diverticula) in the walls of the large intestine (colon), each usually the size of a large pea. You may not have been aware of this because uncomplicated diverticulosis causes no symptoms. Diverticulosis is also frequently discovered as an “incidental finding” on barium X-rays or CT scans done for unrelated reasons.
So if you’ve been given an “incidental” diagnosis of diverticulosis, should you be concerned? In short, no. That said, there are still some things to be aware of.
When -osis becomes -itis
At least half of all Americans develop at least one pouch, if not a few dozen, by age 60. By age 80, about 70 percent have diverticulosis. The concern is not about diverticula per se, but that the pouches can become inflamed and infected. In that case, you have diverticulitis—and you would likely have symptoms, including pain or tenderness (usually on the lower left side of the abdomen), perhaps with nausea, vomiting, constipation, diarrhea, or fever. Milder cases of diverticulitis, caused by microscopic perforations of the diverticula, may improve on their own but usually require antibiotics.
More serious diverticulitis causes substantial abdominal pain and requires urgent medical attention and antibiotics. This occurs when there is more significant perforation of the pouches, around which abscesses can form. Less commonly, bacteria can leak from the intestines into the abdominal cavity and cause a potentially life-threatening infection (peritonitis).
Bleeding from the pouches is another complication of diverticulosis. This is the most common cause of significant lower gastrointestinal bleeding in elderly people, especially if they are taking aspirin or other nonsteroidal anti-inflammatory drugs.
The good news is that diverticulosis doesn’t progress to diverticulitis as often as once thought, according to a UCLA study last year. Many sources say that this happens in up to 25 percent of patients, but in this study, which included some 20,000 people with diverticulosis, only 1 to 4 percent developed diverticulitis over a 7-year period.
The fiber hypothesis
More than 40 years ago, two researchers, Denis Burkitt and Neil Painter, proposed that fiber—or rather, the lack of fiber— plays a major role in the development of diverticulosis, based on their observation that the condition was rare in Africa, where diets were high in fiber. Fiber helps prevent constipation, soften stools, and increase frequency of bowel movements; in contrast, a low-fiber diet results in small hard stools that require the colon to exert more pressure, which over time may lead to the formation of diverticula—or so the theory goes. But scientific data to back this fiber hypothesis are surprisingly limited and conflicting.
For example, an often-cited Oxford University study in the Lancet in 1979 found that diverticular disease was more common among nonvegetarians than vegetarians (who consume more fiber). The authors concluded that their findings confirm the link between low dietary fiber and diverticular disease.
On the other hand, a higher fiber intake was associated with an increased risk of diverticulosis in a 2012 study in Gastroenterology. It included 2,100 people who had undergone colonoscopies to confirm the presence or absence of diverticulosis and were then interviewed about their recent (though not past) diet habits.
Interestingly, some researchers think that the differences in diverticulosis rates among populations may have less to do with fiber than defecation position (sitting, as is the norm in the West, versus squatting, which is common in Africa and Asia).
Findings for other dietary variables have also been inconsistent, with some studies linking diverticulosis to red meat consumption, but others showing that neither red meat nor fat increased the risk.
Diverticulosis is often seen in people with irritable bowel syndrome (IBS), which causes such symptoms as cramping, bloating, gas, and irregular bowel movements. There’s no convincing evidence that diverticulosis contributes to IBS, however; instead, IBS and the formation of diverticula might share a common cause.
Some (not all) studies have also linked diverticulosis to smoking, alcohol, lack of exercise, obesity, and even altered levels of serotonin (a neurotransmitter that affects smooth muscle in the colon). Another theory is that an alteration in intestinal bacteria, possibly diet-related, plays a role. There may be a genetic component too: In a 2013 study in Gastroenterology, people with a sibling who had diverticular disease were three times more likely to develop the condition than the general population.
- Though the link between fiber intake and the development of diverticulosis is still not clear, once diverticula form, a highfiber diet may help prevent diverticulitis. To boost your intake, eat more vegetables, legumes, whole grains, and fruits. Fiber supplements, such as psyllium (found in bulk-forming laxatives like Metamucil), are an additional option. Avoid stimulant laxatives, though.
- You need not avoid nuts, corn, seeds, and popcorn, as doctors used to commonly advise. It was once thought that undigested bits become lodged in the pouches, leading to diverticulitis. But more recent studies have confirmed that such foods are not a problem. You don’t have to worry about foods with small seeds, such as strawberries, raspberries, and tomatoes, either.
- Antibiotics are typically recommended for acute flare-ups, along with a temporary liquid or low-fiber diet. In more severe cases, hospitalization, intravenous antibiotics, and even surgery may be needed.
- For recurrent diverticulitis, medications, including mesalamine (an anti-inflammatory drug), anticholinergics, and antispasmodics may help improve symptoms. Further research is needed to determine whether mesalamine, possibly combined with probiotics (such as L. casei), will prevent recurrences of diverticulitis.