Sen. John McCain was treated for diverticulitis. Experts say this serious gastrointestinal disorder is on the rise in the developed world.

Diverticulitis, the ailment that hospitalized 81-year-old John McCain earlier this month, is becoming more prevalent in the developed world.

McCain, the senior senator from Arizona and decorated Vietnam War veteran, was reportedly in stable condition after undergoing surgery at the Mayo Clinic in Phoenix.

The gastrointestinal disease occurs when abnormal pouches, known as diverticuli, form in the wall of your large intestine and become inflamed and infected.

The ailment is becoming more prevalent in the developed world — partially because of poorly balanced diets, according to an expert interviewed by Healthline.

“It does become more common with age, but it actually affects a lot of young people now in the United States, people in their 20s and 30s,” said Dr. Alan Harzman, a specialist in colon and rectal surgery at The Ohio State University Wexner Medical Center.

“We think it’s related to a high-fat, low-fiber Western-style diet,” he added. “In parts of the world where they eat a lot more fiber than we do in the West, they tend to have a lot less diverticulitis.”

The disease reportedly cost the U.S. healthcare system $2.4 billion in 2013.

As the disease becomes more prevalent, it’s more important than ever for patients and health professionals to understand the ailment, said Harzman.

Generally speaking, symptoms of diverticulitis include pain in your lower-left abdominal area, sometimes accompanied by nausea, diarrhea, or constipation and fever.

“These little pockets at the edge of the colon are almost like little hernias,” said Harzman. “It’s weak there and these little pouches can get inflamed, then rupture, and then you get inflammation around the colon. It can result in stool, or at least air, going through the wall of the colon.”

While the basics of diverticulitis are understood, there are still unknowns when it comes to fully understanding the disease, said Harzman.

“We used to think that we knew very well what the process was, but I think right now we’ve kind of realized that we don’t know as much about exactly why it happens and how it happens as we thought we did,” said Harzman.

Treatment for diverticulitis has changed in recent years, with Harzman noting that there’s growing evidence that some patients don’t need antibiotics for the condition. Another difference is that invasive surgery might not be as necessary as it was once thought to be.

“The more attacks you have, the more likely you are to have another one. Up until about ten or fifteen years ago, if someone was young — under 50 — and they’d had one attack, then we’d recommend that they have their sigmoid colon out to avoid another attack. If they were over 50, we’d do that after two episodes,” explained Harzman.

“But now we’ve figured out that usually the next episode is a lot like the first one,” he added. “So, if you had a fairly mild episode, even if you have another one in a few years, it’ll probably be fairly mild as well. So the morbidity of the surgery to prevent another attack is not nearly as worth it as we thought it was.”

Ultimately, though, for patients who’ve had many diverticular attacks, treatment involves removing the afflicted section of the colon.

Risk factors for diverticulitis include age, family history, lack of physical activity, and diet.

While age and family history can’t be changed, people can minimize their risk by getting active and switching to a healthier diet.

“Eating a high-fiber diet is a way to prevent it,” stated Harzman. “Not everyone forms the little diverticuli that lead to diverticulitis, so the more fiber you eat, the less likely you are to ever form those little pockets.”

Harzman recommends eating a high-fiber diet or taking fiber supplements, not just for the prevention of diverticulitis but also bowel health in general.

For those who are already experiencing symptoms, the best practice is always to consult with your doctor.

“We all have pains that come and go and it’s pretty common to have abdominal pain that comes and goes,” said Harzman. “But abdominal pain that persists for more than a few hours, pain that’s becoming gradually worse, along with other symptoms like fever, nausea, generally feeling ill, and loss of appetite, those are the times you should seek medical attention.”

“It’s a fairly common disease and we think it’s becoming more common over time,” said Harzman. “The basic encouragement is for people to eat a higher fiber diet than most of us do now and to seek medical attention when they start having problems.”