ADVERTISEMENT

Bowels, especially those that don’t function properly, are not a popular topic of conversation. Most of the 1.4 million Americans with inflammatory bowel disease – Crohn’s disease or ulcerative colitis – suffer in silence.

But scientists are making exciting progress in understanding the causes of these conditions and in developing more effective therapies. And affected individuals have begun to speak up to let others know that they are not alone.

Abby Searfoss, 21, who just graduated from the University of Connecticut, shared her story not in a support group, but online. She was a high school senior in Ridgefield, Conn., when she became ill. After she researched her symptoms on the Internet, she realized that, like her father, she had developed Crohn’s disease.

Her father had been very ill, losing 40 pounds, spending weeks in the hospital and undergoing surgery. Soon after Searfoss’ own diagnosis, her two younger sisters learned that they, too, had the condition.

In Crohn’s disease, the immune system attacks cells in the digestive tract, most often the end of the small intestine and first part of the colon, or large intestine. Sufferers may experience bouts of abdominal pain, cramps and diarrhea, often accompanied by poor appetite, fatigue and anxiety.

“You don’t go anywhere without checking where the bathroom is and how many stalls it has,” said Dr. R. Balfour Sartor, a gastroenterologist at the University of North Carolina School of Medicine and a patient himself. “The fear of incontinence is huge.”

Neither Crohn’s disease nor its less common relative ulcerative colitis, which affects only the large intestine, is curable (except, in the latter instance, by removing the entire colon). But research into what predisposes people to develop these conditions has resulted in more effective treatments and has suggested new ways to prevent the diseases in people who are genetically susceptible.

Two concurrent avenues of high-powered research are supported by the Crohn’s and Colitis Foundation of America. One is the CCFA Genetics Initiative, in which scientists are exploring more than 100 genetic factors now known to influence the risk of developing an inflammatory bowel disease, or IBD. The other research effort, the CCFA Microbiome Initiative, has so far identified 14 different bacterial metabolic factors associated with the diseases. By combining findings from the two initiatives, experts now know that certain genes affect the types of bacteria living in the gut; in turn, these bacteria influence the risk of getting an IBD.

Genes identified thus far appear to account for about 30 percent of the risk of developing an IBD, according to Sartor, who is the chief medical adviser of the foundation. Studies of twins underscore the role of genetics. When one identical twin has Crohn’s, the other has a 50 percent chance of also developing it. In the general population, the risk among siblings of a Crohn’s patient is only 5 percent.

Many people carry genes linked to either Crohn’s or ulcerative colitis, but only some of them become ill. Environmental factors that interact with susceptibility genes also play critical roles.

Strong clues to these factors are emerging from a distressing fact: The incidence of IBD is rising significantly both here and in other parts of the world, Dr. Ramnik J. Xavier, chief of gastroenterology at Massachusetts General Hospital in Boston, said in an interview.

“There’s been a huge uptick in China and India as these countries move more toward a Western lifestyle and adopt Western work and dietary patterns,” Xavier said. “IBD cases are now skyrocketing in well-to-do areas of China.”

And when people migrate from a low-incidence area to a higher one like the U.S., the risk of developing an IBD rises greatly among their children. “This clearly shows there’s an environmental impact that we think is multifactorial,” Sartor said in an interview.

“Diet is one obvious factor that affects both the composition of the gut biota and also its function,” he said, referring to the microorganisms that inhabit the gut. “Bacteria eat what we eat, and every bacterium has certain food preferences.”

Diet influences the types and balance of microbes in the gut, and different microbes produce substances that are either protective or harmful. For example, Sartor said, “Certain bacteria that can metabolize the fiber in certain vegetables and grains produce short-chain fatty acids that are believed to protect the gut. They inhibit inflammation and activate immune responses that stimulate recovery from cell injury.”

Another major contributor to the rise in Crohn’s disease in particular is the widespread, often inappropriate use of antibiotics, Sartor said.

“My advice to parents and grandparents is, ‘Let them eat dirt,’ ” he said.

He also suggests that those with a family history of IBD avoid taking nonsteroidal anti-inflammatory drugs like aspirin, ibuprofen and naproxen, which block the action of protective substances in the gut and can cause ulcers in the lower intestine and the stomach. Acetaminophen is safer, he said.

Many patients say undue stress can cause flare-ups of an IBD. And a new study of 3,150 adults with Crohn’s, presented at a recent scientific meeting by Lawrence S. Gaines, a psychologist at Vanderbilt University, suggests that depression increases the risk of active disease a year later.