Bowel trouble examined: irritable bowel syndrome

Bowel trouble examined: irritable bowel syndrome – includes related information on colon motility, perspective with other bowel problems, etc

Bowel trouble examined: irritable bowel syndrome

Irritable bowel syndrome is a common, annoying malady characterized by bloating, gas, abdominal pain and erratic bowel habits. It can often be relieved simply by eating more fibre.

Irritable bowel syndrome (IBS) ranks close to the common cold as a cause of doctor visits and employee absenteeism, and afflicts as many as 20 per cent of Canadians at some time in their lives. Surveys show that almost 10 per cent of people who consult their family doctor do so because of bowel problems, and about half the patients referred to gastroenterologists complain of irritable bowel syndrome. Although it causes much embarrassment, pain and aggravation IBS is not a specific disease nor a forerunner of serious disorders such as inflammatory bowel disease or cancer. It’s a prevalent condition that many ignore or learn to live with, while a few consider it distressing enough to need medical attention. In a sense, it is the bowel’s reaction to being stressed or uptight.

What exactly is irritable bowel syndrome?

Instead of regular bowel movements, IBS sufferers experience episodes of constipation and/or distressful bloating interspersed with days of inexplicably explosive diarrhea. Many have an embarrassing and unexpected need to defecate many times a day and perhaps noisy, gassy intestines.

The medical literature on IBS demonstrates its widespread occurrence among healthy people who never seek a physician’s advice for it. One study, which surveyed 800 students and hospital employees in North Carolina, all healthy and in the prime of life, showed that 29 per cent of them reported loose or frequent stools alternating with constipation; 12 per cent had bowel-related abdominal pain; 18 per cent were constipated (defined as straining on defecation) more than a quarter of the time. As many as 17 per cent of these young adults had symptoms that could be designated as irritable bowel syndrome — although less than half of them bothered to get medical attention for it. The take-home message in our “bowel-obsessed” society is that symptoms may be called a disease only when people think they merit medical advice.

However, IBS symptoms that continue or begin after age 35 should not be ignored, but carefully investigated in case other bowel problems have developed that do need medical treatment.

IBS not a forerunner of serious bowel disorders

Reassuringly, IBS is defined negatively by excluding organic bowel diseases: IBS is not an organic disorder which endangers health. It is not malignant (cancerous); it does not involve structural or metabolic changes; it does not cause anemia and does not inflame the bowel. In fact, IBS is hard to define because there is no distinct pathology (disease-process), although recent evidence suggests that there may be an underlying gut movement disorder in some cases. Women are twice as likely as men to complain about IBS and whites more often than non-whites. In actual fact, IBS may be as prevalent in men as in women, but women tend to consult physicians more than men. (Interestingly, in India, where cultural traditions discourage women from visiting physicians, more men than women seek help for IBS.) Irritable bowel syndrome goes under many colourful but confusing names — spastic colon, nervous bowel, mucous colitis, functional bowel disorder or its British term, intestinal hurry. While some terms aptly describe its main features — crampy pains and erratic bowel emptying — other labels, such as “a touch of colitis” or mucous colitis are misleading because they erroneously imply that IBS involves bowel inflammation and confuse IBS with colitis, which is a serious organic disease. While their initial symptoms may be similar — abdominal pain, diarrhea and uncomfortable defecation — the ultimate course of IBS and colitis are quite different. Irritable bowel syndrome may involve a disturbance of intestinal motility (gut movements that propel stool) not accompanied by inflammation or risk of cancer. By contrast, colitis or inflammatory bowel disease involves severe, bloody diarrhea, rectal bleeding, fever and weight loss and can eventually lead to serious consequences such as colon cancer.

How the bowel works

To understand IBS and other kinds of bowel trouble, one must know how the intestines work. The intestines measure up to 20 feet in an adult, about 11 feet making up the small intestine, the rest the large intestine or colon. The colon, a long segmented tube that connects the small intestine to the anus (stool outlet), is larger in diameter than the small intestine, hence its alternative names — large intestine or large bowel. The intestines extract essential nutrients, fluid and electrolytes (salts such as sodium and potassium chloride) from food and dispose of undigested waste. One to two litres of fluid pass through the colon every day, much of it absorbed in its ascending and transverse sections. The contents are gradually pushed through the bowel by wave-like muscular movements controlled by nerves and hormones. Undigested food may remain in the descending colon for days, while fluids and electrolytes (salts) are reabsorbed into the bloodstream. The unabsorbed food (as a semisolid called feces or stool) is evacuated by a bowel movement.

Stress and psychological influences probably key factors

While the causes of irritable bowel syndrome remain unknown, recent research suggests it may stem largely from underlying psychological disturbances, anxiety or stress that disturb colonic movements (which wax and wane in tune with emotional changes). Many IBS sufferers first notice their symptoms after stressful events such as job loss, divorce, death of a loved one or financial strain. Since the colon is controlled by cerebral nerve pathways (influenced by emotions), stress can stimulate abnormal colonic movements. The influence of anxiety on the gastrointestinal tract is all too familiar — witness the “butterflies in the tummy” of those awaiting a desired date, examination or public appearance. Emotional stress can profoundly affect the smooth muscles of the intestines, some people reacting more intensely than others — a few even feeling nauseous or throwing-up. (The nervous system of the intestines has been called the “little brain.”)

Although recent studies on irritable bowel syndrome have focused more on colon motility than psychological influences, some people have underlying psychiatric disturbances that somatize or show up as intestinal symptoms. Two U.S. studies recently showed that approximately 50 per cent of those reporting IBS also have signs of psychiatric illness — such as depression or anxiety disorders. By comparison, only one-fifth of patients with organic gastrointestinal diseases (such as colitis) had accompanying depression or anxiety syndromes. These results suggest that in some people a psychiatric disorder unrelated to IBS may manifest itself as a bowel problem. On the other hand, people with chronic abdominal pain due to intestinal problems may develop psychological imbalances. Yet others exhibit “learned illness behaviour” and complain about physical problems to gain attention denied them by other means. Thus, IBS is a benign condition handled differently by different sufferers — some just ignoring it, others (who may be anxious, uncertain or fear “loss of control”) seeking medical attention and still others focussing on it because of underlying depression or other psychological disturbances. The impact of IBS may be exaggerated if sufferers shun social gatherings or avoid activities such as air-travel because of their unpredictable bowel habits. While not all patients with IBS are psychologically disturbed, many share the following features: * a tendency to regard minor illnesses (e.g., a common cold)

as very serious; * more frequent visits to physicians than others; * a history of being pampered as children, given treats when

sick and allowed to stay home from school more often than

other children; * other family members with IBS — suggesting “learned

illness behaviour.”

The fibre connection

Some specialists think that lack of fibre increases bowel irritability while others feel there is only tenuous evidence for its benefits in IBS. The use of high fibre diets in treating IBS is based more on theory than scientific observation. Some investigators claim that IBS is due to “small and slow moving” Western stools compared to those of African populations. Small, hard Western stools are blamed on the popularity of diets rich in processed foods but low in fibre. Whether Africans really suffer less IBS than North Americans isn’t known, although fibre does increase stool output and speed its transit. If symptoms worsen after eating more fibre or consuming particular foods (e.g., milk products, coffee or fried items) — they should be avoided!


Since IBS involves no organic changes, diagnosis must exclude other disorders that produce similar symptoms and rule out the presence of colitis, diverticulitis, bowel cancer and conditions such as lactose intolerance (an inability to digest milk). A sigmoidoscopy may be done to look for bowel tumours, polyps or inflammation. If bowel movements are persistently uncomfortable, X-rays may be ordered to rule out specific diseases. X-rays can detect motility (movement) disorders by measuring the time taken for stool to pass through the colon. If the medical examination shows nothing organically wrong, the sufferer will likely be told that the problem is due to abnormal contractions of an irritable but otherwise healthy bowel.

COPYRIGHT 1990 Strategic Inc. Communications Ltd.

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