What is IBS?
Irritable bowel syndrome (IBS) is among the most common gastrointestinal (GI) disorders, affecting around 1 in 10 people globally.
IBS is considered a disorder of the gut-brain axis (the way the gut and the brain communicate with one another).
Symptoms include intermittent abdominal pain accompanied by diarrhoea, constipation, or alternating episodes of both. Bloating or distention of the abdomen is also common.
What causes it?
The exact underlying cause of IBS is unknown, but is likely to be multifactorial. Factors such as genetics, previous gut infections, malnutrition and adverse life experiences (i.e. trauma) can predispose someone to get IBS. Possible mechanisms for this include changes to the balance of gut bacteria, gut hypersensitivity, and also changes to gut motility (how it contracts and relaxes). Some studies have found that women are twice as likely to be affected by IBS than men (1).
Symptoms may be triggered by certain foods, stress, and menstruation.
How is it diagnosed?
There is no specific test to diagnose IBS, and therefore diagnosis is made based on symptoms, after your doctor has ruled out other causes (such as coeliac disease or Inflammatory bowel disease).
How is it treated?
There is no cure, but there are a few ways it can be managed including:
1. Lifestyle changes
- Stress management
- Dietary changes
- Sleep optimisation
- Regular exercise
Antispasmodics, anti-diarrhoeal, and laxatives may be purchased over the counter or prescribed by your GP. In some cases antidepressants are prescribed to help manage symptoms. Peppermint oil capsules have also shown to be effective in reducing pain and bloating in IBS (2).
3. Psychological and behavioural therapy
Your GP may refer you for talk therapy, such as cognitive behavioural therapy (CBT), if other treatment options are not helping with your symptoms.
IBS and diet
First line dietary changes for IBS management include:
- Establishing a regular eating pattern: This helps to regulate gut function and reduces the risk of ‘overloading’ the gut with possible trigger foods in one go, as compared with eating bigger, less frequent meals.
- Eating slowly and chewing your food thoroughly: aiming for 20 chews per mouthful is often recommended.
- Limiting dietary triggers*: These triggers vary between different people but often include ‘gut stimulants’ like alcohol, caffeine and sweeteners such as sorbitol, mannitol and xylitol. Other common dietary triggers include: fried or fatty foods, spicy food and ‘gassy vegetables’ like Brussels sprouts, beans and lentils. Some people are also sensitive to high-fibre foods. If you are working with a Dietitian, they may ask you to keep a food and symptom diary to help you to identify possible trigger foods.
- Limit fruit to 3 portions per day, including limiting fruit juice to one small (150ml) glass per day.
- Aim to drink 1.5-2L of water per day.
- If symptoms include constipation, you can try adding some flaxseed to your diet, gradually building up to 1 tablespoon per day while making sure to drink plenty of fluids. Fibre supplements such as psyllium are another option which may be recommended on a case by case basis.
- If you want to give probiotic supplements a go the advice from the National Institute for Health and Care Excellence (NICE) is you should take one specific probiotic for at least 4 weeks to see if your symptoms show any signs of improvement. It is best to do this at a time when you are not starting other changes as well. If there is no noticeable improvement after 4 weeks, you can try switching to another probiotic for 4 weeks. Probiotics don’t improve symptoms for everybody, so it can take some experimenting to see whether you notice any benefit or not.
*Note: IBS is extremely common in those with disordered eating. So for those who are malnourished or under-fuelling, the main focus is meeting your nutritional requirements, and weight restoration where appropriate, before looking at possible dietary triggers. This should be done with support from a Dietitian, as in this case further restriction can make the situation worse.
Other lifestyle changes which can improve IBS management include:
- Stress management techniques like meditation, yoga and journaling. Some people benefit from psychological support with stress management. There is some evidence that gut-directed hypnotherapy can improve IBS symptoms (3).
- Regular low to moderate intensity forms of movement like walking, stretching or a leisurely jog or cycle.
- Focusing on sleep hygiene i.e. establishing a regular sleep pattern and bedtime routine, optimising the bedroom environment for sleep and See here for more information about sleep hygiene.
The Low-FODMAP diet
If symptoms persist following first line dietary advice and general lifestyle advice, a low-FODMAP diet may be recommended under the guidance of a dietitian who has training and experience with the low-FODMAP diet.
FODMAPs are a group of carbohydrates that have been linked with worsened IBS symptoms. Not everybody is sensitive to high-FODMAP foods, but many people have a specific tolerance level to these.
FODMAP stands for:
Fermentable i.e. capable of being fermented in the gut
Oligosaccharides i.e. fructans and galactooligosaccharides (GOS), found in onions, garlic, wheat, rye, beans and pulses
Disaccharides i.e. lactose which is found in most dairy products, including milk, yogurt, ice cream and certain soft cheeses
Monosaccharides i.e. fructose, found in foods like honey, apples and mango
Polyols i.e. the sugar alcohols sorbitol and mannitol, found in sugar-free sweets and chewing gum as well as certain fruit and vegetables
With this diet, FODMAPs are avoided for 4-6 weeks, before gradually reintroducing each FODMAP to see which high-FODMAP foods (if any) and which amounts of these foods trigger IBS symptoms.
Note: The low-FODMAP diet is restrictive, so it should only be followed in the short term with the support of a trained health professional. Following the full low-FODMAP diet for a longer period of time may do more harm than good in terms of gut health, nutritional intake and your relationship with food. This diet is not suitable for everyone, so please seek support if you are considering this.
(1) Khanbhai & Singh Sura (2013) “Irritable Bowel Syndrome for Primary Care Physicians” [accessed April 2021 via: https://www.bjmp.org/content/irritable-bowel-syndrome-primary-care-physicians]
(2) Alammar N, Wang L, Saberi B, Nanavati J, Holtmann G, Shinohara RT, Mullin GE. The impact of peppermint oil on the irritable bowel syndrome: a meta-analysis of the pooled clinical data. BMC complementary and alternative medicine. 2019 Dec;19(1):1-0.
(3) Peter et al. (2016) “Randomised clinical trial: the efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome” Aliment Pharmacol Ther. 44(5): p. 447-59.