Deconstructing Irritable Bowel Syndrome

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Presented by: Linda Nguyen, MD
Clinical Assistant Professor, Gastroenterology
Director, Gastrointestinal Motility and Neurogastroenterology
Stanford University Medical Center
October 14, 2009

Lecture Overview:

  • Irritable bowel syndrome is a chronic condition characterized by cramping, bloating, and changes in bowel habits.
  • As much as 20 percent of adults have symptoms of IBS, making it one of the most common disorders diagnosed by doctors.
  • Stress tends to exacerbate the symptoms and can affect how a person perceives the problem as well as delay seeking appropriate medical help.
  • Though there’s no one cure for IBS, most people can control their symptoms with diet, stress management, and prescribed medications.

Irritable bowel syndrome (IBS) is a disorder characterized by recurrent cramping, abdominal pain, bloating, and changes in bowel habits, such as constipation or diarrhea. As much as 10 to 20 percent of the adult population have symptoms of IBS, making it one of the most common disorders diagnosed by doctors, even though only about 15 percent go on to seek medical attention. Because of its frequency, its costs are estimated to be about $30 billion a year in health care, work absenteeism, and lost productivity. It occurs more often in women than men, and its first symptoms usually arise in the late teens or early 20s.

The symptoms of IBS vary from person to person: Some people have constipation; others experience chronic diarrhea, and some alternate between the two or have symptoms that come and go. One concern for doctors is that there is a broad range of normal stool.

“It’s up to you to know what’s normal and what’s not normal.” said Linda Nguyen, MD, director of Stanford’s Gastrointestinal Motility and Neurogastroenterology program, at a presentation sponsored by the Stanford Hospital Health Library. “Your definition may be different than your doctor’s.”

IBS is caused by any alteration in the process of digestion-from ingestion to elimination-that affects motility (the movements throughout the tract that aid digestion). While there is no one root cause of the disorder, one theory is that people who suffer from IBS have visceral hypersensitivity-they have a lower threshold to pain and are particularly sensitive to stretching in the digestive tract. These people may not necessarily have more pain but are more conscious of it: Nguyen estimates that between 50 and 70 percent of people with IBS have altered perceptions of pain.

Another cause of IBS may be inflammation caused by a viral or bacterial infection, or food poisoning. Long after the incident is over, the person may still have symptoms that can last as long as four or five years. About 40 percent of these people recover, said Nguyen, but the rest may suffer from IBS for the rest of their life. “The initial inflammation alters their nerve sensitivity,” she said.

Stress tends to exacerbate the symptoms and can affect how a person perceives the problem as well as delay seeking appropriate medical help.

While there’s no definitive test to identify IBS, diagnostic tests, including colonoscopy or sigmoidoscopy, may be used to rule out other problems. Certain symptoms, like rectal bleeding, severe pain, or weight loss, are not typical symptoms of IBS and may be signs of another, serious disorder. Physicians will base a diagnosis on a complete medical history that includes a careful description of symptoms and a physical examination. Nguyen suggests you come prepared to your doctor’s visit with your most pressing questions and share your concerns right off.

Lactose intolerance, small bowel bacterial overgrowth, and some pelvic floor disorders can mimic the symptoms of IBS. While lactose intolerance affects about 90 percent of Asians, it occurs in only 15 to 25 percent of IBS patients. “Take away the lactose, and they still have the symptoms,” said Nguyen.

Despite all the mimickers, one study showed that 97 percent of IBS patients had the same symptoms for more than five years, despite changes in diet. To Nguyen, that means it’s especially important to establish a long-term relationship between patient and gastroenterologist to constantly re-evaluate the condition.

Though there’s no real cure for IBS, most people can control their symptoms with diet, stress management, and prescribed medications. Many medications, including some antispasmodics, have shown side effects disproportionate to their benefits and have been taken off the market. Antidepressants can help reduce pain sensitivity but do not address the real symptoms.

Nguyen has found that about 25 grams of fiber a day helps many people with constipation, although she warned that more than that amount can cause bloating. ¬†Patients’ with diarrhea can look to over-the-counter antidiarrheal medication, adding fiber to their diet, using antispasmodics or antidepressants, and assessing their diet for excess magnesium or fructose. All patients should try to reduce spicy foods, caffeine, high-fructose corn syrup, and foods that tend to induce gas, such as broccoli, beans, and salad. Omega-3 fatty acids, found in fish, flaxseed, and walnuts, may help improve symptoms, as may probiotics, found in some yogurts.

“The goal is to improve quality of life and reduce symptoms. Despite what everyone wishes, it’s a condition that only be controlled with diet and behavior modification,” Nguyen said. “It’s important to identify your triggers and to develop coping mechanisms to regain as much control as possible.”

About the Speaker
Linda Nguyen, MD, is a clinical assistant professor of medicine (gastroenterology and hepatology) and director of Stanford’s GI Motility and Neurogastroenterology program.¬† She received her MD from UCLA School of Medicine and did her residency and fellowship at California Pacific Medical Center. A specialist in gastrointestinal motility, Nguyen is Board Certified in Gastroenterology from the American Board of Internal Medicine.

For More Information:

Stanford Health Library can do the searching for you. Send us your medical questions.

About Dr. Nguyen
http://med.stanford.edu/profiles/gastrohep/researcher/Linda_Nguyen/

Gastroenterology at Stanford Hospital
http://stanfordhospital.org/clinicsmedServices/clinics/gastroenterology/

The Division of Gastroenterology and Hepatology
http://gastrohep.stanford.edu/