What is IBS? Symptoms, Causes, Diagnosis & Dietary Management

What is IBS?

IBS stands for irritable bowel syndrome. It is a chronic gastrointestinal disorder which presents with altered bowel habits; diarrhoea and/or constipation, abdominal pain and distention with no structural or biochemical abnormalities. 3

There are three types of IBS:

  1. Diarrhoea predominant IBS (IBS-d)
  2. Constipation predominant IBS (IBS-c) and
  3. Mixed/alternating IBS (IBS-m or IBS-a). This is were the symptoms alternate between diarrhoea and constipation.

Symptoms include: 3

  • diarrhoea and/or constipation
  • abdominal pain or discomfort
  • wind
  • bloating
  • passing mucus
  • a feeling of urgency
  • feeling the need to open bowels just after being to the toilet
  • feeling that your symptoms are worse after eating

Look at the Bristol Stool Chart below to help identify your stool consistency. Type 1-3 indicate constipation, type 4 and 5 are considered as normal and 5-6 indicate loose stools.

What causes IBS?

The cause is still unknown however it is thought that genetics and environment do play a role.

How is IBS diagnosed? 2,3

IBS is diagnosed by using the Rome III criteria. IBS diagnosis is considered if the individual has abdominal pain or discomfort that is relieved by defecation or is associated with altered bowel frequency or stool form for at least 6 months with at least two of the following: 3

  • Altered stool frequency (>3x daily or <x3 times/week)
  • Altered stool form (hard/loose)
  • Altered stool passage (straining, urgency, sense of incomplete evacuation)
  • Passage of mucus
  • Symptoms worsened by eating
  • Abdominal bloating or feeling of distension
  • Other common features such as lethargy, nausea, backache and bladder symptoms and may be used to support the diagnosis

Diagnosis of IBS is usually done after ruling out other possible conditions such as coeliac disease. It is important for other conditions to be ruled out first. Make sure your GP carries out the following tests: 3

  • a full blood count (FBC)
  • erythrocyte sedimentation rate (ESR) or plasma viscosity **
  • c-reactive protein (CRP) **
  • antibody testing for coeliac disease.

**The ESR and CRP tests are conducted to detect inflammation in the body which can be caused by inflammatory bowel disease.

Other tests such as ultrasound and colonoscopy may be carried out but these may not be necessary to confirm diagnosis. 3

Red flag indicators for further investigations include unintentional and unexplained weight loss, rectal bleeding, a family history of bowel or ovarian cancer and a change in bowel habit persisting more than 6 weeks in a person aged over 60 years. 3 If you are experiencing any of these symptoms speak with your GP.

Is there a cure?

Unfortunately no. Medication and diet can be used to manage the symptoms.

How to manage IBS symptoms through diet:

The general first line advice is to: 1,2,3

  • Eat three small regular meals with snacks in between. Smaller meals may help ease symptoms.
  • Avoid missing meals or leaving long gaps between eating as this may exacerbate symptoms.
  • Eat slowly and chew food well to aid its digestion.
  • Avoid eating late at night
  • Drink at least 8 cups of fluid per day; especially water
  • Reduce intake of fried and fatty foods such as fast food, cheese, chocolate, crisps, cakes, burgers, sausages, spreads and cooking oils. Fatty meals may induce abdominal pain and bloating.
  • Reduce intake of processed foods.
  • Be active. Aim for 30 minutes of exercise 5 times a week.
  • Find time to relax.
  • Avoid consumption of bran as it is rich in insoluble fibre which can exacerbate symptoms.
  • Reduce alcohol consumption. Alcohol is an irritant to the gut and can exacerbate symptoms.

Additional advice for diarrhoea-predominant IBS:

  • Avoid sorbitol, mannitol and xylitol commonly found in diet or sugar free products. Check food labels.
  • Limit high fibre foods. Opt for white varieties instead of wholegrains such as white bread instead of wholegrain bread and cornflakes instead of weetabix.
  • Limit intake of fruit to three portions per day. A portion is approximately 80g.
  • Limit caffeine intake from tea, coffee, energy drinks and soft drinks such coca cola, pepsi as caffeine is a stimulant and irritant to the gut. Limit to three glasses a day.
  • Limit fruit juice to one glass a day.

Additional advice for constipation-predominant IBS:

  • Dietary fibre may help with constipation but tends to generate gas, stimulate contractions and make pain, bloating, flatulence and diarrhoea worse. NICE clinical guideline 61 advises that fibre intake should be adjusted according to its effect and reduced if necessary. If you do increase your fibre intake, do so gradually, because any sudden increase may make symptoms worse.
  • Trial wholegrains and introduce these slowly into the diet. Monitor symptoms of gas and bloating.
  • Aim for at least 5 portions of fruit and vegetables per day. Raw vegetables and skins on fruit and vegetables contain insoluble fibre. Some IBS sufferers struggle to digest these. Remove skins and seeds to improve tolerance and opt for cooked vegetables if raw vegetables exacerbate symptoms.
  • Oats and ground flaxseeds/linseeds are good sources of soluble fibre, which help to soften the stool and make it easier to pass; they may also help with symptoms of wind and bloating.
  • Trial ground linseeds/flaxseeds. These have been shown to improve constipation, abdominal pain and bloating. However it may take 6 months to notice improvements. Start with 1 tsp and build up to 1 tbsp per day. Take with 150mls of water a day to help soften stool. The ground linseeds can be added to food such as yoghurt, cereal, soups and salad.
  • Ensure a good fluid intake – at least 8 cups of non-caffeinated fluid a day.

Advice for wind and bloating:

  • Reduce intake of resistant starch found in processed or re-cooked foods. Starchy foods include potatoes, rice and pasta. Avoid reheating these. Eat freshly cooked rice and potatoes. Try using fresh pasta instead of dry pasta to minimise symptoms.
  • Limit fruit to 3 portions a day and fruit juice to 1 small glass a day. Remember to make up the recommended ‘5 a day’ with vegetables.
  • Limit intake of gas producing foods such as cabbage, beans, pulses, broccoli, Brussels sprouts, cauliflower and onion.
  • Limit intake of sugar free sweets and chewing gum.

 Further advice:

  • Lactose can cause wind, bloating and diarrhoea for some. Trial lactose free milk and lactose free dairy products for  a week. Ensure the lactose free products are fortified with calcium. If there are no improvements in symptoms reintroduce  ordinary milk and dairy products.
  • There is some evidence that probiotics can be beneficial. Probiotics should be trialed for 4 weeks to notice a difference in symptoms. Symptoms tend to worsen before they improve. If there is no improvement an alternative brand may be trialled or probiotics can be stopped.
  • Keep a food and symptom diary to help identify any triggers and monitor changes in symptoms.
  • Aim for at least 5 portions of fruit and vegetables per day. Raw vegetables and skins on fruit and vegetables contain insoluble fibre. Some IBS sufferers struggle to digest these. Remove skins and seeds to improve tolerance and opt for cooked vegetables if raw vegetables exacerbate symptoms.
  • Make one change at a time so you can identify what is helping.

Ask your GP to refer you to a dietitian for dietary advice in removing common IBS triggers, help identifying possible triggers, ensuring nutritional adequacy and trialing the low FODMAP diet. The low FODMAP diet has been clinically shown to improve symptoms in 70% of IBS sufferers.


  1. BDA, 2013. UK evidence-based practice guidelines for the dietetic management of irritable bowel syndrome (IBS) in adults. UK: BDA.
  2. McKenzie Y, Alder A, Anderson W, Willis A, Goddard L, Gulia P, Jankovich E, Mutch P, Reeves L, Singer A and Lomer M, 2012. British Dietetic Association evidence-based guidelines for the dietary management of irritable bowel syndrome in adults. Journal of Human Nutrition and Dietetics; 25: 260-274.
  3. NICE CG61, 2015. Irritable bowel syndrome in adults: diagnosis and management of irritable bowel syndrome in primary care. Available at https://www.nice.org.uk/guidance/cg61/resources/guidance-irritable-bowel-syndrome-in-adults-diagnosis-and-management-of-irritable-bowel-syndrome-in-primary-care-pdf

5 thoughts on “What is IBS? Symptoms, Causes, Diagnosis & Dietary Management

  1. Thanks for caring about the IBS community, MEVSIBS.

    I find that whole grains (insoluble) are problematic whenever I experience a flare-up. I increase my soluble fiber with foods like cooked fruits (skins removed) and Benefibre. Low FODMAP didn’t work for me, but everyone is different.

    Liked by 1 person

    1. You’re most welcome Kathy. As an IBS sufferer myself I know how difficult dealing with IBS can be. You are very right everyone with IBS is very different from the symptoms experienced, their severity and responses to treatment. All this makes it that much harder to treat. When it comes to the low FODMAP diet it only works for approximately 70% of patients. I am sorry to hear it did not work for you but it looks like you have identified other common dietary triggers. Recent research has found that gut directed hypnotherapy is as effective as the low FODMAP diet. It may be something worth considering if your symptoms are still impacting on your daily activities.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s