Irritable Bowel Syndrome (IBS) Causes, Symptoms, Diet, Treatment

What is irritable bowel syndrome?

Irritable bowel syndrome, or IBS for short, is a bowel disorder that is associated with abdominal pain and changes in bowel habit. It is a functional bowel disorder meaning that there is no evident disease process but is rather associated with a disturbance in the normal functioning of the bowel. IBS is also known by another now outdated term – ‘spastic colon’. It is often confused with IBD (inflammatory bowel disease) which is another common yet less prevalent disorder that is due to actual disease processes affecting the bowels.

It is estimated that IBS affects over 20% of the adult population and is one of the common causes for absenteeism but often cases of inflammatory bowel disease need to be identified as it is frequently mistaken for IBS. The diagnosis of IBS should be made by a doctor and should only be confirmed once all relevant diagnostic investigation, like a colonoscopy and stool tests, reveal no underlying disease. Unlike with IBD (inflammatory bowel disease), there is no risk of colon (colorectal) cancer with irritable bowel syndrome.

Causes of Irritable Bowel Syndrome

The cause of IBS is unknown although several common trigger factors affect all patients. IBS is primarily a disorder with gastrointestinal motility – this is the movement of food, its digested remnants and waste matter through your bowels. Some patients appear to have more rapid gastrointestinal motility and tend to present more frequently with diarrhoea. These cases are referred to as diarrhoea-predominant IBS. Others have slower than normal motility, allowing the stools to become hard and therefore tend to experience constipation more frequently. This type of IBS is known as constipation-predominant IBS. It is not uncommon for some IBS patients to fluctuate between periods of diarrhoea and constipation.

IBS appears to a disorder with the muscles and/or nerves of the bowel wall. It may also be linked to psychosocial factors. People who are more stressed, have a history of abuse and/or mood disorders like anxiety or depression appear to be more likely to suffer with IBS. This is not relevant to every IBS sufferer, however, emotional stress does seem to exacerbate the condition in every patient. It also appears that the condition is more likely to develop after a severe gastrointestinal infection, like gastroenteritis, or may be linked to allergies and food sesitivity like lactose intolerance. Hormonal factors may also be a consideration especially in women as changes with the menstrual cycle, pregnancy, use of oral contraceptives and even menopause seem to either exacerbate or relieve the IBS. Certain foods and drinks, particularly dairy, caffeinated beverages and spicy foods, tend to aggravate the condition but are not a cause of IBS. Cigarette smoking and excessive alcohol consumption may also be trigger factors.

Signs and Symptoms of IBS

Three key features of irritable bowel syndromes includes :

  • Change in bowel movements
  • Abdominal pain, cramping or discomfort
  • Abdominal bloating

These symptoms may not be present all the time, and most IBS patients learn how to manage their condition. However, acute episodes (flareups) may arise with certain trigger factors or even for unknown reasons and last a period of time. Some IBS patients have one or more of these symptoms present all the time, although it is usually mild until a flareup occurs.

Bowel Movements

As mentioned above, IBS patients may have mainly diarrhoea or constipation. Some may alternate between periods of diarrhoea or constipation. However, this is not present at all times and may not be characteristic of diarrhoea and constipation. Therefore an IBS sufferer, particularly those with diarrhoea-predominant IBS) may report very frequent  bowel movements although the stool is well formed and not large in volume. Typically these patients tend to have an urge to defaecate after eating any meal but especially spicy foods and this can be even within minutes after finishing a meal.

Others may find that although they can pass stool and are not constipated as such, it requires a long sitting on the toilet, and some straining and effort on their part. Even a slight disturbance or distraction for these patients will affect the ability to defaecate. These patterns are common for IBS patients but cannot be accurately defined by clinical terms such as diarrhoea or constipation.

Abdominal Pain or Discomfort

Not every IBS sufferer experiences bouts of abdominal pain or discomfort. It was the severe pain, often described as intestinal cramps, that led to the term ‘spastic colon’. It was believed that the muscles in the bowel wall suddenly go into spasm and this elicits pain. However, even those IBS sufferers who do not experience pain will report some unusual bowel sensation or discomfort during the flareups. This may also be associated with gas in the bowels which may present as excessive flatulence.

Abdominal Bloating

Although the term bloating is used, the correct term is distension. IBS sufferers tend to experience actual expansion of the abdomen that is clearly visible and which can change within hours. This is known as functional bloating. It is not uncommon for an IBS patient to have a ‘blown out’ tummy during acute flareups or even on certain days with no other symptoms, yet this can ease significantly with hours, after a night of sleep or at the very most within days. Bloating in this regard, however, must be differentiated from abdominal obesity, ascites (fluid accumulation in the abdomen) and bloating linked to the menstrual cycle (women).

Other Symptoms of IBS

The signs of symptoms of IBS are non-specific gastrointestinal symptoms – meaning it does not specifically indicate IBS and can be due to a host of other disorders. Some of the other symptoms may include :

  • Excessive belching (burping), particularly after meals
  • Excessive flatulence (farting)
  • Indigestion
  • Changes in appetite
  • Loud bowel sounds (borborygmi)
  • Heartburn
  • Depression and irritability

It is important to ensure that all the IBS symptoms are not due to some underlying disorder, that may have always been present or only started up afterwards. For example, heartburn may be due to acid reflux associated with dysfunction of the lower esophageal sphincter and is not a consequence of IBS.

Diet for Irritable Bowel Syndrome

The effectiveness of dietary modification in IBS is often debated. IBS patients try out fad diets and nutritional products specifically for their condition and find that it may only work for a short period of time. Whether these diets were actually of any use or its short-lived effects were just psychosomatic often remains unanswered. However, there has been some success with basic dietary changes like avoiding dairy, spicy foods and other trigger foods that a person knows will aggravate the condition. While some foods are common to most IBS patients, it is largely an individual sensitivity and therefore recording the effect of different foods in a food diary is encouraged. These results should be discussed with a doctor and dietitian to formulate an eating plan that will work best for the individual.

The low FODMAP diet is gaining more recognition worldwide as an eating plan that is fairly successful in helping IBS patients manage their condition. FODMAP is the abbreviation for Fermentable Oligo-, Di- and Mono-saccharides, and Polyols. FODMAPS are a type of short-chain carbohydrate found in many foods that we commonly eat. The low FODMAP diet postulates the these foods irritate the bowel wall, increase fluid and gas volume within the bowel and therefore leads to many of the symptoms seen with IBS despite there being no detectable pathological change in the bowel. It is advisable to discuss a low FODMAP diet with your dietitian before commencing it or changing any part of your prescribed treatment.

Treatment for IBS

The treatment for IBS is largely symptomatic. Since the cause cannot be identified and there is no detectable pathological changes observed in the bowel, the focus is on management. Here medication and lifestyle changes aim to prevent flareups or at least reduce the severity of these episodes. Palliative treatment is prescribed during these acute episodes and often discontinued once the condition settles. However, fibre supplements, probiotics and tricylclic antidepressants appear to be useful in managing IBS over the long term in most patients. New drugs may directly act on the nerves supplying the bowel wall but is not utilised for every IBS patient. The treatment and management of IBS should be overseen by your general practitioner in conjunction with a gastroenterologist. The involvement of other healthcare professionals like a psychologist and dietitian may be necessary.