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Irritable Bowel Syndrome

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What is Irritable Bowel Syndrome (IBS)?

Irritable bowel syndrome (IBS) is a disease of the digestive system that is both common and long-term. It is estimated to affect approximately 1 person in 5 at some point in their lives. However it most commonly occurs in adults in their 20s and 30s, and effects twice as many women as men [Ref].

Irritable bowel syndrome (IBS) is a recurring and chronic functional bowel disorder. It  consists of abdominal pain, cramping, bloating, gas, diarrhoea, and constipation (Hungin et al., 2014). IBS affects the small and large intestines, causing symptoms in the gut or bowel. It is a “syndrome” because it is a group of various symptoms that aggravate the gut; however, these symptoms may be expressed differently depending on the individual (Gucht, 2015). IBS is also considered a “gut-brain interaction” or disorder because the brain influences the gut, for instance, through stress and anxiety (Drossman, 2016) [Ref].

Irritable Bowel Syndrome is usually diagnosed by using symptom-based criteria. This is because there are no specific biological markers for the diagnosis (Hungin et al., 2014) [Ref].

As there are no tests available in allopathic medicine that allow doctors to be absolutely positive about the diagnosis, it is often given on a balance of probabilities. This balance depends upon the type of symptoms a person registers, as well as their severity and any known factors that make them better or worse. For this reason It has recently been suggested by a group of experts that there are a set of symptoms that can be used to make a positive diagnosis of IBS, with a good degree of reliability, via the use of the “Rome criteria”.

Symptoms of Irritable Bowel Syndrome

What causes IBS is unclear.  It appears that sensory nerves in the bowel can be hypersensitive in people with IBS. Also the intestinal muscles can be hyperactive.

But many factors can provoke symptoms. Stress is often cited as a contributory element as is eating irregularly or following abnormal diet. Overall, an interaction occurs between the nervous system in both the gut and brain, as well as  the immune system of the gut.

In simple terms irritable bowel syndrome can be diagnosed when an adult presents with continuous symptoms or symptoms that have been recurrent for at least three months. These will include abdominal pain or discomfort which is:

  • relieved by defaecation
  • and/or associated with a change in the frequency of stools
  • and/or associated with a change in the consistency of stools plus two or more of the following, at least a quarter of occasions or days
Other symptoms include:
  • more than three stools per day or less than three per week
  • altered stool form (lumpy/hard or loose/watery)
  • altered stool passage (straining, urgency or feeling of incomplete evacuation)
  • passage of mucus
  • bloating or feeling of abdominal distension
  • nausea

So, a doctor can be fairly certain of making a diagnosis of IBS if this pattern of symptoms is present. Equally a diagnosis requires that there are no other major symptoms present and a physical examination is normal. However it is very important to see get advice from your GP in the first instance to discuss your symptoms and to be examined and to receive an official diagnosis and guidance.


There is a lack of formal diagnostic criteria for IBS, so it is typically diagnosed by exclusion of other bowel conditions such as Inflammatory Bowel Disease (IBD), Diverticulitis and Colon Cancer. When a full blood count, erythrocyte sedimentation rate (ESR) or plasma viscosity, C-reactive protein (CRP) and antibody testing for coeliac disease come back negative, you’ll be diagnosed with IBS if you continue to present with the symptoms.

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Causes of Irritable Bowel Syndrome

Because IBS symptoms are largely generalised, it is often difficult to diagnose the underlying cause of the condition, and there is as yet no specific known reason for its development.

Some scientists have suggested it is due to an over sensitive colon or an immune system irregularity. There is also a chance that it may be caused by a bacterial infection of the digestive tract, genetic factors, altered intestinal permeability, abnormalities in serotonin metabolism or changes in bile salt production.

Triggers are more the focus of IBS. Factors like stress are well-known to have an impact on the digestive system, and it is believed that heightened nervous system output may overstimulate the bowels and disrupt regular digestive processes. As women are at higher risk of developing IBS symptoms. It is believed that a woman’s menstrual cycle can disrupt normal bowel function, which is why many women experience more severe IBS symptoms during their periods.

Diet is another huge consideration for the management of IBS symptoms, and many patients can manage their condition by eating the right types of foods. Additionally, the way in which you eat can have an impact. Eating too quickly, while distracted, constantly grazing, or eating on the run can trigger symptoms.

Finding the root cause of Irritable Bowel Syndrome

While IBS is one of the most common gut conditions we see, it is important for us to consider what else is going on when you are affected by a variety of gut-related and other possible symptoms. When we begin investigating your symptoms.

Treatment of Irritable Bowel Syndrome

Nutrition and Irritable Bowel Syndrome

Unlike other bowel conditions which have specific tests for a diagnosis,  IBS is more elusive. Indeed irritable bowel syndrome does not cause easily detectable abnormalities in the digestive system. As a result everyone can be affected differently and with varying severity.

In fact the exact cause of IBS is unknown. The symptoms of irritable bowel syndrome are similar to many other conditions. Therefore before making any dietary changes,  it is a good idea to consult your GP as well as a nutritional therapist to rule-out Inflammatory Bowel Disease or other bowel conditions.

So the most important step to take is to identify and share your symptoms clearly with your GP or your nutritional therapist.

Common dietary triggers for IBS include: drinking either fizzy or caffeinated drinks, alcoholic drinks, many types of processed snacks, and fatty foods. So reducing the intake of these, or other discernible triggers, is a sensible starting point for alleviating symptoms.

Equally high‑fibre food (like wholemeal flour and breads, cereals high in bran, and whole grains like brown rice can be triggers. A nutritionist can review your fibre intake and make recommendations to adjust your intake with you, whilst monitoring the effects.

A professional nutritional therapist will work with you to understand what triggers your symptoms. They will also carry out assessment and give guidance on any possible positive lifestyle changes that you can make.

Dietary changes often help to relieve symptoms of irritable bowel syndrome, and some sufferers will need to add probiotic supplements as a regular part of their diet.

What happens when you get an IBS diagnosis?

When an individual is diagnosed with IBS, the GP may refer them to a dietician or other healthcare professional, who may recommend a special elimination diet called the FODMAPS diet. This diet seems to work by altering the inflammation in the gut often found with IBS, which is caused by altered gut microbiome. FODMAPs are fermentable, short-chain carbohydrates which for some sensitive individuals, become fermented in the colon because the small intestine cannot complete absorption of these foods. (this may be because the individual has SIBO (see SIBO section)). In other words, when foods containing FODMAPs are fermented in the colon, gas, pain, bloating, diarrhoea and/or constipation, and other gut sensitivities, may result.

Occasionally, the GP service may suggest that an OTC generic probiotic could be tried. Probiotics are beneficial bacteria that can have various health benefits when taken. There is some good evidence that selected key strains of probiotics may be helpful for individuals with IBS, but the GP may not be able to recommend these specific probiotics as few have been officially included in NICE guidelines.

Patients with irritable bowel syndrome are often prescribed medication for their symptoms by healthcare professionals. Pharmacological treatments are prescribed based on specific IBS symptoms. For IBS-C, laxatives are used, such as lactulose or Movicol, to name a few. Unfortunately, common side effects from laxatives are abdominal pain, diarrhoea, nausea, and distention. For IBS-D, loperamide (brand name Imodium) is usually the first medication prescribed. For bloating and gas symptoms of IBS, an antispasmodic is used (Buscopan), which helps relax the muscles. Typical side effects for antispasmodics include nausea, vomiting, altered taste, dry mouth, blurred vision, dysphagia, palpitations, and urinary hesitancy and retention. If there are psychological diagnoses, the first-line medication is typically a selective serotonin reuptake inhibitor (SSRI). SSRIs are proposed to change an individual’s threshold of pain for IBS symptoms; however, it is not known how they treat depression or anxiety for an IBS patient specifically. The second line of pharmacological treatment includes tricyclic antidepressants, which have the potential for more negative side effects than SSRIs.

How does IBS clinics use functional medicine to resolve IBS?

Functional Medicine differs from the standard conventional or allopathic medicine model in that it determines how and why illness occurs and restores health by addressing the root causes of disease for each individual.

The Functional Medicine model is a highly individual, patient-centred, science-based approach that empowers patients and practitioners to work together to address the underlying causes of disease and promote optimal wellness. It requires a detailed understanding of each patient’s genetic, biochemical, and lifestyle factors and leverages that data to direct personalised treatment plans that lead to improved patient outcomes. By addressing root cause, rather than symptoms, it is possible to identify the complex nature of disease. It is often found that a health condition has a variety of different causes and, likewise, one cause may result in many different conditions. As a result, Functional Medicine treatment targets the specific manifestations of disease in each individual.

Special functional tests may be recommended to uncover the underlying causes for an individual’s IBS. Comprehensive stool tests are one such test commonly used to assess digestive and metabolic gut function, identify gut infections and bacterial imbalances or overgrowth. The vast majority of IBS clinics patients will be recommended to test for SIBO as this is a common contributing factor to IBS. Between 60-73% of our patient demographic will have SIBO as a single contributing factor, but often accompanied by other factors. Food intolerance testing can also be helpful to identify problem foods which may be contributing to IBS and there is some good research to support this in IBS sufferers.

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