April 23 (HealthDay News) -- Irritable bowel syndrome (IBS) is a common disorder that affects 10 percent to 15 percent of people in the United States but is misunderstood by many patients and doctors, says Dr. William D. Chey, a gastroenterologist at the University of Michigan Health System.

"There are a wide spectrum of symptoms that IBS patients can experience, which can make it challenging to diagnose. While we know diet does play a role in symptoms for many patients with IBS, those 'trigger foods' often vary from person to person," Chey, director of U-M's Gastrointestinal Physiology Laboratory, said in a prepared statement.

Symptoms of IBS include cramping, abdominal pain, bloating, constipation and diarrhea. To help people with IBS gain a better understanding of the condition, Chey offered the following information about the condition:

• IBS does not exist in the patient's head. While psychological distress or stress can make IBS worse, they're not the primary cause of the condition in most cases.
• IBS occurs more frequently in women but "it's important that people know that there are many men diagnosed with IBS, and it also affects the elderly. In fact there's some early evidence to suggest that IBS affects 8 to 10 percent of older individuals," Chey said.
• Many doctors believe IBS is not an important condition because it doesn't affect a person's lifespan. But Chey said IBS can have a significant negative effect on quality of life and the ability to function on a day-to-day basis, and should be taken seriously by both doctors and patients.
• Lactose intolerance may play a role in some cases of IBS, but it's not the cause of symptoms in the vast majority of people.
• Most people with IBS don't need to limit themselves to bland diets. Chey recommended that patients keep a diary of the food they eat and IBS symptoms. "At the end of a two-week period, it's possible to get a fairly good idea about whether there are specific trigger foods associated with the onset of symptoms. Those foods then can be easily eliminated from a patient's diet," he said. Chey noted that fatty foods, milk products, chocolate, alcohol, caffeine and carbonated drinks are more likely to aggravate IBS symptoms.
• It doesn't require a lot of medical testing to diagnose IBS. "Identifying the presence of persistent recurrent abdominal pain in association with altered bowel habits, and excluding warning signs (e.g. new symptoms occurring after age 50, GI bleeding, unexplained weight loss, nocturnal diarrhea, severe or progressively worse symptoms or a family history of colon cancer, inflammatory bowel disease, colon cancer or celiac disease), is enough to accurately diagnose IBS in most patients," Chey said.
• Effective counseling, dietary and lifestyle changes, and medication can help patients effectively manage IBS.