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What is Functional Bowel Disorder?
A functional bowel disorder (FBD) is the term used for a group of conditions which cause digestive symptoms without the presence of structural abnormalities. Symptoms may include:
- Diarrhoea
- Constipation
- Bloating
- Excessive wind
- Urgency to open your bowels
- Feeling the need to go to the toilet when you have just been
- Passing mucous
- Nausea
- Acid reflux
- Symptoms may be worse after eating
It is not normal to pass blood, consult your doctor if this occurs.
All individuals who suffer with a form of FBD will experience a different combination of symptoms which can vary in frequency and severity.
Irritable bowel syndrome (IBS) is a subtype of FBD which is associated with a 6-month history of abdominal pain or bloating associated with a change in bowel habit in the absence of structural abnormality.
IBS is quite common and is thought to affect between 7-21% of the adult population.
Diagnosis
Diagnosis of FBD is a diagnosis of exclusion. It is important to have your diagnosis of FBD confirmed by a doctor to ensure they have ruled out other conditions such as coeliac disease and inflammatory bowel disease. Although FBD can cause significant discomfort and may impact your quality
of life it does not cause permanent damage to the gut and does not increase the risk of other bowel related conditions.
What Causes FBD?
The cause of FBD is not fully understood, but the following have been identified as possible triggers:
Stress
Stress and anxiety can contribute towards the development of symptoms,and you may notice your symptoms worsen during periods of stress.
Antibiotics
Antibiotics can disrupt the good bacteria in your gut. This may result in symptoms as discussed on page one.
Gut Hypersensitivity
Some individuals have an exaggerated response to normal gut sensations. It means individuals with FBD may experience pain or discomfort from stimuli, such as food, that would typically be considered normal or painless by others.
Food Intolerance
There is a possibility that your symptoms may be related to a food intolerance however there is no evidence to support any commercially available food intolerance tests. Identification of food intolerances usually involves excluding the presumed food trigger from the diet for a period of
time to monitor for symptom improvement. We recommend you seek support from a dietitian before commencing an exclusion diet to prevent inadequate nutrient intake and malnutrition.
Improvement to Symptoms
There is no cure for IBS, but research over the last ten years has shown that 75% of patients with IBS improve their symptoms by implementing dietary changes.
Step 1: What can I do to relieve my symptoms?
Consider the dietary and lifestyle recommendations below:
- Eat three regular meals per day or alternatively try to have 4-6 smaller, more frequent meals.
- Try to avoid skipping meals or eating close to bedtime.
- Eat slowly and chew your food thoroughly.
- Try to sit at a table and avoid distractions whilst you eat.
- Drink at least eight cups of fluid per day opting for water or caffeinefree drinks such as herbal teas.
- Reduce caffeine containing drinks to two mugs or three cups per day.
- Limit alcohol intake to 2 units per day (14 units per week) in line with government recommendations.
- Reduce intake of fizzy drinks.
- Avoid very fatty or fried foods.
- Make exercise part of your lifestyle. Aim to complete 150 minutes of moderate intensity exercise per week e.g. brisk walking, cycling, swimming, dancing.
- Take time to relax e.g. making time for your hobbies/participating in mindfulness activities such as yoga or meditation.
- Consider contacting Talking Therapies if you feel that stress and anxiety are making your symptoms worse (details on following pages
The plate above shows the different types of food we need to eat and in what proportion across the day, to have a well-balanced diet.
You could also try keeping a food and symptom diary (example included in this leaflet). It is important that you make one dietary change at a time so you can identify possible triggers.
Record the time of symptom onset to help you identify dietary, environmental or emotional triggers. For example, state how you are feeling at certain points throughout the day e.g. anxious or eating ‘on the go’ or eating later than usual or a larger than normal meal. It is important to remember your symptoms may be caused by what you ate the day before or what you ate earlier, rather than what you have just eaten.
Step 2: If this has not worked, what next?
If you do not find step one has helped to provide adequate relief after trialling these suggestions, it may be necessary to eliminate certain foods. It is important to only eliminate one food at a time, to help identify which particular food is causing your symptoms. This is a process of trial and error and may take some time, but if completed thoroughly, may greatly improve your symptoms and quality of life.
Diarrhoea
- Make sure you drink around 2 litres (8 glasses) of fluid per day and replace lost fluid with water and non-caffeinated drinks; limit fizzy drinks
- Limit alcohol to 2 units per day (14 units per week) in line with government recommendations.
- Reduce caffeine containing drinks to two mugs or three cups per day.
- Limit high fibre foods (see table opposite).
- Limit fresh fruit and resistant starches (see next page)
- Avoid sugar-free sweets e.g. mints and chewing gum and foods containing the sweeteners, sorbitol, mannitol and xylitol.
- Reduce high fat foods, such as chips, sausages, cheese, cream crisps, cakes and takeaways.
Constipation
- Gradually increase fibre in the diet to find your tolerance level - (see table opposite). In particular, increase fruit, vegetables and oats. Prunes and kiwi fruit can be helpful (introduce gradually).
- Avoid eating extra wheat bran.
- Drink at least 2 litres (8 glasses) of fluid per day.
- Trial linseeds. (info on following pages)
- Make regular exercise part of your lifestyle.
- If dietary measures are insufficient discuss the use of laxatives with your GP
| Low fibre foods | High fibre foods |
| White bread | Wholemeal, granary or white bread with added fibre |
| White rice | Brown or wholegrain rice |
| White pasta | Brown or wholegrain pasta |
| Potatoes without the skin | Potatoes with skin |
| Rice or corn based cereals, e.g. Cornflakes, Rice Krispies |
Wholegrain cereals like muesli, Weetabix, bran flakes, oats |
| Cream crackers, rice cakes | Wholewheat crackers, rye crispbreads |
| Meat, fish, poultry, milk, yoghurts and cheese |
Nuts and seeds |
| Smooth peanut butter, Quorn, eggs | Beans and pulses including tinned baked beans and lentil soup |
| Fruits without skin, pith and pips – peeled apples, pears, peaches, nectarines, pineapple, apricots, plums, grapes, melon, banana, fruit juice |
Kiwi, mango, grapefruit, oranges, rhubarb, unripe bananas, strawberries, raspberries and other berries, prunes |
| Fruit cocktail | Dried fruit, smoothies |
| Vegetables – peeled or skinned: carrot, celery, beetroot, broccoli, cauliflower, courgette, lettuce, marrow, cucumber, turnip, tomatoes without pips, pepper, radish, spinach, squash, swede |
Sprouts, cabbage, garlic, onions, leeks peas, sweetcorn, green beans, mushrooms |
| Plain biscuits and cakes, puddings or pastries made with white flour |
Wholewheat biscuits and cakes or those with dried fruit in e.g. digestives, fig rolls, cereal bars, fruit cake |
| Jelly, ice cream, milk jelly, milk puddings, honey, jam, fine cut marmalade |
Jam with seeds and skin, thick cut marmalade, fruit chutneys and pickles |
If your symptoms include wind and bloating
- Limit fresh fruit to three portions. This includes one portion of dried fruit and one 150ml glass of fruit juice per day. You may need to increase your vegetable intake to ensure you achieve your “5-a-day”.
One portion of fruit or vegetable is 80g.
- Limit gas producing foods
- Beans and pulses e.g. lentils, peas, chickpeas
- Brussels Sprouts
- Cauliflower
- Cabbage
- Kale
- Leeks
- Broccoli
- Limit intake of resistant starches. These are foods which resist digestion in the small intestine, ferment and then produce gas, causing wind and/or bloating. They are often found in processed or reheated foods such as:
- Undercooked or reheated potato – make sure you eat these whilst hot and fresh
- Part-baked and reheated breads, e.g. garlic bread, pizza base
- Processed food e.g. potato/pasta salad, oven chips, potato waffles, fried rice, crisps or manufactured biscuits or cakes
- Ready meals containing pasta or potato e.g. lasagne, shepherd’s pie, macaroni cheese
- Dried pasta - try fresh pasta instead
- Increase intake of oats; for example, by having an oat-based cereal or porridge for breakfast.
- Consider adding linseeds to your diet. Start with one teaspoon and gradually increase to two tablespoons per day. Linseeds can be added to foods such as cereal, yoghurt, soup or salad. It is important to drink at least 150ml of fluid per tablespoon of linseeds. We recommend you trial this for three months.
- Avoid sugar-free sweets e.g. mints and chewing gum and foods containing the sweeteners, sorbitol, mannitol and xylitol.
Step 3: Probiotics
If you have implemented the advice above and your symptoms are still present you could consider trying a probiotic. Probiotics are live microorganisms which can help to restore the balance of good bacteria in the gut.
The scientific evidence for the use of probiotics is growing and some probiotics have shown promise in helping to reduce symptoms in patients with FBD. There are multiple brands of probiotics which each contain a variety of different strains of bacteria. There is limited evidence to recommend a particular brand as every individual has a different variety of gut bacteria.
It is recommended that you trial one brand at a time and follow the recommended dose for four weeks and monitor the effect. If you notice an improvement in your symptoms you should continue to take them, however if you do not notice any improvement, you could trial an alternative brand or
stop them, as probiotics may not work for everyone.
IBS Webinar
You can receive first line dietary advice for IBS from our online webinar, where you can listen to expert dietary advice from local NHS specialist dietitians and download the latest information, all from the comfort of your own home.
Just send a blank email to fhft.ibswebinar@
subject line. We will then send you a link to the webinar which you can watch on your computer, tablet or mobile phone. Please check your spam folder if you have not heard from us within one week.
Step 4: None of this has helped, what now?
Remember, diet is not the only cause of FBD and it may be something unrelated that is the main cause of your symptoms, such as stress.
Talking Therapy Services is a free NHS service that you can self-refer to. This service has therapists who are trained to support people with a long-term physical conditions who may be struggling with sleep, worry, low mood or managing their long term condition.
GP in Slough, Windsor, Ascot, Maidenhead or Bracknell:
https:/
GP in Aldershot, Farnborough, Fleet, Farnham or Yateley:
http://
For anyone registered with a GP in Camberley, Frimley, Bagshot, Ash Vale and Virgina water:
https:/
Depending on your symptoms, your dietitian may suggest excluding certain food groups (e.g. milk or wheat-free diet) or going on an exclusion diet or low FODMAP diet. These need the supervision of a dietitian as they can lead to serious nutrient deficiencies and malnutrition if not undertaken properly.
Some Useful Websites
https://
Contact us
If you have any queries relating to this information, please contact the Dietetics service.
About this information
Service:
Dietetics
Reference:
DT/033
Approval date:
1 July 2025
Review date:
1 July 2028
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.