The exact cause of irritable bowel syndrome (IBS) is unknown, but most experts think that it’s related to problems with digestion and increased the sensitivity of the gut. Many causes have been suggested – including inflammation, infections and certain diets – but none have been proven to directly lead to IBS.
Problems with digestion
Your body usually moves food through your digestive system by squeezing and relaxing the muscles of the intestines in a rhythmic way. However, in irritable bowel syndrome, it’s thought that this process is altered, resulting in food moving through your digestive system either too quickly or too slowly. If food moves through your digestive system too quickly it causes diarrhoea, because your digestive system does not have enough time to absorb water from the food. If food moves through your digestive system too slowly it causes constipation, as too much water is absorbed, making your stools hard and difficult to pass. It may be that food does not pass through the digestive systems of people with IBS properly because the signals that travel from the brain to the gut are disrupted in some way. Increased gut sensitivity many sensations in the body come from your digestive system. For example, nerves in your digestive system relay signals to your brain to let you know if you are hungry or full, or if you need to go to the toilet. Some experts think that people with irritable bowel syndrome may be oversensitive to the digestive nerve signals. This means mild indigestion that is barely noticeable in most people becomes a distressing abdominal (stomach) pain in those with irritable bowel syndrome.
There is also some evidence to suggest that psychological factors play an important role in irritable bowel syndrome. Intense emotional states such as stress and anxiety can trigger chemical changes that interfere with the normal workings of the digestive system. This does not just happen in people with irritable bowel syndrome. Many people who have never had irritable bowel syndrome before can have a sudden change in bowel habits when faced with a stressful situation, such as an important exam or job interview. Some people with irritable bowel syndrome have experienced a traumatic event, usually during their childhood, such as abuse, neglect, a serious childhood illness or bereavement. It is possible that these types of difficult experiences in your past may make you more sensitive to stress and the symptoms of pain and discomfort.
Certain foods and drinks can trigger the symptoms of IBS. Triggers vary from person to person, but common ones include:
• cold drinks
• chocolate, ice creams
• drinks that contain caffeine – such as tea, coffee or cold drinks (coke, Pepsi)
• processed snacks – such as crisps and biscuits
• fatty or fried food
Keeping a food diary may be a useful way of identifying possible triggers in your diet. Stress is another common trigger of irritable bowel syndrome symptoms. Therefore, finding ways to manage stressful situations is an important part of treating the condition.
A diagnosis of irritable bowel syndrome depends largely on a complete medical history and physical examination. A diagnosis of IBS will then be considered if you have stomach pain or discomfort that is either relieved by passing stools or is associated with a need to go to the toilet frequently or a change in the consistency of your stools.
This should be accompanied by at least two of the following four symptoms:
• a change in how you pass stools – such as needing to strain, feeling a sense of urgency or feeling you have not emptied your bowels properly
• bloating, hardness or tension in your stomach
• your symptoms get worse after eating
• passing mucus or slime with stools
We may recommend several tests, to rule out infection or problems with your intestine’s ability to take in the nutrients from food (malabsorption). You may undergo a number of tests to rule out other causes such as cancer.
• Flexible sigmoidoscopy. This test examines the lower part of the colon (sigmoid) with a flexible, lighted tube (sigmoidoscope).
• Colonoscopy. In some cases, especially if you are age 50 or older or have other signs of a potentially more serious condition, your doctor may perform this diagnostic test in which a small, flexible tube is used to examine the entire length of the colon.
• Computerized tomography (CT) scan. CT scans produce cross-sectional X-ray images of internal organs. CT scans of your abdomen and pelvis may help your doctor rule out other causes of your symptoms, especially if you have abdominal pain.
• Lactose intolerance tests. Lactase is an enzyme you need to digest the sugar found in dairy products. If you don’t produce this enzyme, you may have problems similar to those caused by irritable bowel syndrome, including abdominal pain, gas and diarrhoea.
• Blood tests. Celiac disease is sensitivity to wheat, barley and rye protein that may cause signs and symptoms like those of irritable bowel syndrome. Blood tests can help rule out this disorder. Children with IBS have a far greater risk of celiac disease than do children who don’t have IBS. If your doctor suspects that you have celiac disease, he or she may perform an upper endoscopy to obtain a biopsy of your small intestine.
• Stool tests. If you have chronic diarrhoea, doctors may want to examine your stool for bacteria or parasites.
The symptoms of irritable bowel syndrome (IBS) can often be managed by changing your diet and lifestyle. In some cases, medication or psychological treatments may also be helpful.
IBS-friendly diet Changing your diet will play an important part in controlling your symptoms of IBS. The diet that works best for you will depend on your symptoms and how you react to different foods. It may be helpful to keep a food diary and record whether certain foods make your symptoms better or worse. You can then avoid foods that trigger your symptoms. However, it’s important to remember that these foods will not necessarily need to be avoided for life.
People with IBS are often advised to modify the amount of fibre in their diet. There are two main types of fibre: soluble fibre (which the body can digest) and insoluble fibre (which the body cannot digest). Foods that contain soluble fibre include:
• fruit – such as bananas and apples
• root vegetables – such as carrots and potatoes
Foods that contain insoluble fibre include:
• whole grain bread
• nuts and seeds
If you have diarrhoea, you may find it helps to cut down on the insoluble fibre you eat. It may also help to avoid the skin, pith and pips from fruit and vegetables.
If you have constipation, increasing the amount of soluble fibre in your diet and the amount of water you drink can help. The dietician at CALOMS may be able to advise on what your recommended fibre intake should be.
Low FODMAP diet If you experience persistent or frequent bloating, a special diet called the low FODMAP diet can be effective. FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are types of carbohydrates that aren’t easily broken down and absorbed by the gut. This means they start to ferment in the gut relatively quickly, and the gases released during this process can lead to bloating. A low FODMAP diet essentially involves restricting your intake of various foods that are high in FODMAPs, such as some fruits and vegetables, animal milk, wheat products and beans. If you want to try the low FODMAP diet, it’s best to do so under the guidance of a professional dietitian, who can ensure your diet is still healthy and balanced.
General eating tips
Your IBS symptoms may also improve by:
• having regular meals and taking your time when eating
• not missing meals or leaving long gaps between eating
• drinking at least 1/2 to 3 litres of water a day.
• restricting your tea and coffee intake to a maximum of two cups a day
• reducing the amount of alcohol and fizzy (e.g. Pepsi, Coke) drinks.
• reducing your intake of resistant starch (starch that resists digestion in the small intestine and reaches the large intestine intact), which is often found in processed or re-cooked foods
• limiting fresh fruit to three portions a day – a suitable portion would be an apple
• if you have diarrhoea, avoiding sorbitol, an artificial sweetener found in sugar-free sweets, including chewing gum and drinks, and in some diabetic and slimming products
• if you have wind (flatulence) and bloating, it may help to eat oats (such as oat-based breakfast cereal or porridge) and linseeds (up to one tablespoon a day)
Many people find that exercise helps to relieve the symptoms of IBS.
Aim to do a minimum of 150 minutes of moderate-intensity aerobic activity, such as cycling or fast walking, every week.
The exercise should be strenuous enough to increase your heart and breathing rates.
Reducing your stress levels may also reduce the frequency and severity of your IBS symptoms. Some ways to help relieve stress include:
• relaxation techniques – such as meditation or breathing exercises
• physical activities – such as yoga, pilates or tai chi
• regular exercise – such as walking, running or swimming
If you are particularly stressed, you may benefit from a talking therapy, such as stress counselling or cognitive behavioural therapy (CBT).
Probiotics are dietary supplements that product manufacturers claim can help improve digestive health. They contain so-called “friendly bacteria” that can supposedly restore the natural balance of your gut bacteria when it has been disrupted. Some people find taking probiotics regularly helps to relieve the symptoms of IBS. If you want to try a probiotic product, you should take it for at least four weeks to see if your symptoms improve.
A number of different medications can be used to help treat IBS, including:
• antispasmodics – which help reduce abdominal (stomach) pain and cramping
• laxatives – which can help relieve constipation
• antimotility medicines – which can help relieve diarrhoea
• low-dose antidepressants – which were originally designed to treat depression, but can also help reduce stomach pain and cramping independent of any antidepressant effect
These medications are discussed in more detail below. Antispasmodics work by helping to relax the muscles in your digestive system. Examples of antispasmodic medicines include mebeverine and therapeutic peppermint oil. Side effects associated with antispasmodics are rare. However, people taking peppermint oil may have occasional heartburn and irritation on the skin around their bottom. Laxatives Bulk-forming laxatives are usually recommended for people with IBS-related constipation. They make your stools softer, which means they are easier to pass. It’s important to drink plenty of fluids while using a bulk-forming laxative. This will help prevent the laxative from causing an obstruction in your digestive system.
The antimotility medicine loperamide is usually recommended for IBS-related diarrhoea. Loperamide works by slowing contractions of muscles in the bowel, which slows down the speed at which food passes through your digestive system. This allows more time for your stools to harden and solidify.
There are several different types of psychological therapy. They all involve teaching you techniques to help you control your condition better, and there is good evidence to suggest they may help some people with IBS. Psychological treatments that may be offered to people with IBS include:
• psychotherapy – a type of therapy that involves talking to a trained therapist to help you to look deeper into your problems and worries
• cognitive behavioural therapy (CBT) – a type of psychotherapy that involves examining how beliefs and thoughts are linked to behaviour and feelings and teaches ways to alter your behaviour and way of thinking to help you cope with your situation
• hypnotherapy – where hypnosis is used to change your unconscious mind’s attitude towards your symptoms Complementary therapies
Some people claim therapies such as acupuncture and reflexology can help people with IBS.