Disorder of the Gut–Brain Interaction (DGBI) Specialist in Oxford, Banbury and Aylesbury

Specialist assessment for IBS, bloating, abdominal pain, nausea, reflux hypersensitivity and persistent digestive symptoms despite normal tests

Disorder of the Gut–Brain Interaction (DGBI) is a modern term used for a group of common digestive conditions in which symptoms are very real, but standard tests may not show inflammation, cancer, ulceration or another structural disease.

These conditions were previously often called “functional gastrointestinal disorders”. Modern gastroenterology increasingly uses the term Disorders of Gut–Brain Interaction because it better reflects what is happening: the gut, nerves, immune system, microbiome and brain are communicating differently.

This does not mean symptoms are imagined, psychological or “all in the mind”. It means the digestive system has become more sensitive, less predictable, or more reactive than expected. With the right assessment and a structured treatment plan, symptoms can often be improved significantly.

Dr Udit Mittal provides consultant-led assessment and management of Disorders of Gut–Brain Interaction in Oxford, Banbury, Aylesbury, and surrounding areas such as Bicester, Buckinghamshire, Milton Keynes, Northampton, the Cotswolds and North London, including patients with persistent digestive symptoms despite normal tests.

Book a consultation

View consultation fees

Read about endoscopy and colonoscopy or view our full range of gastroenterology services

What is a Disorder of the Gut–Brain Interaction?

Your digestive system is controlled by a highly sophisticated network of nerves, hormones, immune signals, gut bacteria and brain pathways. This system regulates digestion, gut movement, sensation, appetite, nausea, pain and bowel habit.

How the gut–brain axis affects digestion and symptoms

The gut and brain are in constant two-way communication. The gut sends information to the brain about stretch, gas, digestion, inflammation, bacteria, hormones and movement. The brain also sends signals back to the gut that influence motility, secretion, appetite, nausea and sensitivity.

In a Disorder of Gut–Brain Interaction, this communication can become amplified or dysregulated. Normal digestion may be felt as pain, pressure, nausea, urgency or bloating. Stress can worsen symptoms, but stress is not the only cause. Symptoms can also begin after gastroenteritis, antibiotics, food poisoning, surgery, inflammation, major life events, sleep disruption or sometimes without a clear trigger.

Why symptoms are real even when tests are normal

A person can have severe symptoms even when tests are reassuring. Normal tests do not mean the symptoms are not real. They often mean that the problem lies in gut function, sensitivity and signalling rather than visible structural damage.

In a Disorder of Gut–Brain Interaction, symptoms may arise from one or more of the following:

• increased gut sensitivity, sometimes called visceral hypersensitivity
• altered bowel movement, causing diarrhoea, constipation or alternating bowel habit
• changes in the gut microbiome after infection, antibiotics, diet change or stress
• altered immune or mucosal signalling after gastroenteritis or inflammation
• heightened signalling between the gut and nervous system
• changes in how the brain processes normal digestive sensations
• overlap with sleep disturbance, anxiety, stress, pain syndromes or fatigue
• pelvic floor dysfunction or impaired coordination during bowel emptying

A useful way to explain it is this: The gut is not damaged, but the signalling system has become over-alert. Treatment is therefore aimed at calming the gut, reducing sensitivity, improving bowel pattern and restoring confidence in digestion.

Common symptoms of Disorders of Gut–Brain Interaction

DGBI can affect the oesophagus, stomach, small bowel, colon, rectum and anus. Symptoms vary between patients and may fluctuate over time.

Common symptoms include:

• abdominal pain or cramping
• bloating or visible abdominal distension
• diarrhoea
• constipation
• alternating diarrhoea and constipation
• urgency to open the bowels
• incomplete bowel emptying
• excessive belching or burping
• nausea
• early fullness after meals
• reflux-type symptoms despite normal endoscopy
• chest or throat discomfort after cardiac and structural causes have been excluded
• food-related symptom flares
• mucus in the stool
• symptoms worsening after infection, stress, poor sleep or dietary change

Some patients have one main symptom. Others have overlapping symptoms affecting more than one part of the digestive tract.

Conditions included under Disorders of Gut–Brain Interaction

DGBI is not one single diagnosis. It is an umbrella term covering several recognised conditions.

Common examples include:

Irritable Bowel Syndrome (IBS)

IBS is one of the best-known Disorders of Gut–Brain Interaction. It can cause abdominal pain or discomfort with diarrhoea, constipation or mixed bowel habit. IBS does not damage the bowel and does not increase the risk of bowel cancer, but it can have a major impact on quality of life.

Functional Dyspepsia

Functional dyspepsia can cause upper abdominal discomfort, fullness after meals, early satiety, nausea, bloating or burning discomfort despite a reassuring gastroscopy or scan.

Functional Bloating and Abdominal Distension

Some patients experience troublesome bloating, abdominal pressure or visible distension. This may relate to gas handling, gut sensitivity, dietary fermentation, constipation, abdominal wall reflexes or gut–brain signalling.

Reflux Hypersensitivity and Functional Heartburn

Some people experience heartburn, chest discomfort, throat symptoms or acid reflux-type symptoms even when endoscopy is normal and acid exposure is not clearly abnormal. In these cases, the oesophagus may be more sensitive to normal reflux events or normal stretching.

Chronic Nausea and Vomiting Syndromes

Persistent nausea, recurrent vomiting, cyclic vomiting and related symptom patterns may sometimes fall within the DGBI spectrum after appropriate assessment.

Supragastric Belching and Rumination Syndrome

Excessive belching or effortless regurgitation may sometimes be driven by learned gut–brain behavioural patterns rather than acid reflux alone. These conditions are genuine and treatable, but often need a different approach from standard reflux medication.

Functional Constipation and Pelvic Floor Dysfunction

Constipation may be due to slow movement through the bowel, stool consistency, diet, medication, pelvic floor coordination problems or altered rectal sensation.

Centrally Mediated Abdominal Pain Syndrome

A smaller group of patients experience persistent abdominal pain where pain signalling itself has become amplified. This requires careful diagnosis, explanation and a structured non-opioid pain management plan.

How DGBI is diagnosed

Rome V and clinical diagnosis

The Rome criteria are internationally recognised diagnostic frameworks used by specialists to classify Disorders of Gut–Brain Interaction.

Rome V, the latest framework, places greater emphasis on:

• patient-centred diagnosis
• physiologically accurate language
• the difference between research criteria and real-world clinical diagnosis
• overlap between different gut–brain interaction disorders
• multidisciplinary care, including dietetic, behavioural and medical treatment
• reduced reliance on the older word “functional”, which many patients find dismissive

Rome V also recognises that patients do not always describe symptoms using strict medical terms. In practice, diagnosis is made by combining:

• a careful symptom history
• red flag assessment
• examination where appropriate
• targeted blood and stool tests
• review of medication, diet and previous infections
• selected endoscopy, colonoscopy or imaging when clinically indicated
• consideration of Rome criteria alongside clinical judgement

A diagnosis of DGBI should be a positive diagnosis, not simply “nothing was found”.

When blood tests, stool tests, endoscopy or colonoscopy may be needed

Many patients with DGBI have already had normal investigations. However, it is important not to assume that every digestive symptom is due to gut–brain interaction.

Further assessment may be needed if there are red flag features such as:

• unintentional weight loss
• blood in the stool or rectal bleeding
• iron deficiency anaemia
• persistent vomiting
• progressive difficulty swallowing
• new bowel habit change, particularly later in life
• night-time diarrhoea
• fever or raised inflammatory markers
• family history of bowel cancer, coeliac disease or inflammatory bowel disease
• abnormal stool tests such as raised faecal calprotectin
• symptoms beginning after age 50 without previous assessment

The aim is to investigate carefully where needed, while avoiding repeated tests that do not add value once serious conditions have been appropriately excluded.

Endoscopy or colonoscopy may be recommended if symptoms, age, blood tests, stool tests or family history suggest that structural disease should be excluded. If endoscopy is not needed, this will also be explained clearly.

Why can symptoms persist when tests are normal?

This is one of the most common and frustrating experiences for patients.

A normal gastroscopy, colonoscopy, CT scan or MRI is reassuring because it reduces the likelihood of serious structural disease. However, these tests do not directly measure gut sensitivity, nerve signalling, microbiome function, gut motility, pelvic floor coordination or how the brain interprets gut signals.

For example:

• a colonoscopy can show that the lining of the bowel is healthy, but not whether the bowel is over-sensitive
• a gastroscopy can exclude ulcers or cancer, but not always explain nausea or fullness
• a CT scan can exclude a mass or inflammation, but not measure gut–brain signalling
• blood tests can be normal even when symptoms are very disruptive

This is why a clear explanation matters. Patients often improve when they understand the mechanism and have a plan that targets the actual driver of symptoms.

Treatment for Disorders of Gut–Brain Interaction

Treatment should be personalised. There is no single treatment that works for everyone.

A structured plan may include several of the following.

Explanation and positive diagnosis

Understanding the diagnosis is treatment in itself. Many patients have been told that tests are normal but have not been given a clear explanation. A positive diagnosis helps reduce uncertainty and allows treatment to move forward.

Diet and nutrition

Diet can be very helpful, but overly restrictive diets can sometimes make symptoms, anxiety and nutrition worse.

Options may include:

• regular meals and adequate hydration
• reducing excessive caffeine, alcohol, fizzy drinks or ultra-processed foods
• soluble fibre such as ispaghula in selected patients
• constipation-focused dietary adjustment
• a dietitian-guided low FODMAP approach where appropriate
• reintroduction and personalisation rather than long-term unnecessary restriction
• assessment for lactose intolerance, coeliac disease or bile acid diarrhoea where clinically relevant

Patients with weight loss, food fear, nutritional deficiency, eating disorder history or multiple food exclusions should be managed carefully with dietetic support.

Bowel habit optimisation

For diarrhoea, treatment may include antidiarrhoeal medication, bile acid diarrhoea treatment where suspected, dietary adjustment or treatment of overlapping conditions.

For constipation, treatment may include osmotic laxatives, fibre adjustment, stimulant laxatives, secretagogues, prokinetics or pelvic floor assessment depending on the pattern.

Gut sensitivity treatment and neuromodulators

Low-dose gut neuromodulators can help some patients with pain, nausea, diarrhoea, reflux hypersensitivity or visceral sensitivity. These medicines are often used at much lower doses than when prescribed for mood disorders.

Examples include low-dose tricyclic medicines such as amitriptyline or nortriptyline, or other neuromodulators in selected cases. They are not prescribed because symptoms are imagined. They are used because they can reduce overactive pain and sensitivity signalling between the gut and nervous system.

The choice depends on symptoms, bowel habit, sleep, other medication, cardiac risk, pregnancy plans and patient preference.

Gut-directed behavioural therapies

Gut-directed cognitive behavioural therapy, gut-directed hypnotherapy, relaxation training, diaphragmatic breathing and mindfulness-based approaches can be helpful for selected patients.

These treatments are not the same as being told “it is stress”. They are designed to retrain gut–brain signalling, reduce symptom amplification and improve self-management.

They can be particularly useful when symptoms are triggered by meals, urgency, nausea, pain, bloating or fear of symptoms occurring in public.

Pelvic floor assessment and anorectal testing

In patients with constipation, incomplete emptying, straining, urgency, leakage or rectal discomfort, pelvic floor dysfunction may contribute. Tests such as anorectal physiology, balloon expulsion testing or referral to pelvic floor physiotherapy may be appropriate.

When to seek medical advice urgently

Seek urgent medical advice if you develop vomiting blood, black stools, severe or worsening abdominal pain, fainting, persistent vomiting, chest pain, new difficulty swallowing, significant rectal bleeding, or rapidly worsening symptoms. In an emergency, please call 999 or attend your nearest Emergency Department.

Private DGBI, IBS and gut–brain interaction assessment in Oxfordshire and Buckinghamshire

Dr Udit Mittal sees patients with IBS and Disorders of Gut–Brain Interaction at the following locations:

Oxford

Private consultations for DGBI, IBS, bloating, abdominal pain, nausea and reflux hypersensitivity are available in Oxford.

Banbury

Specialist assessment for gut–brain interaction disorders is available for patients in Banbury and North Oxfordshire.

Aylesbury

Private gastroenterology consultations for persistent digestive symptoms are available in Aylesbury.

Also serving Buckinghamshire, Bicester, Milton Keynes, Northampton, the Cotswolds and North London

Appointments are suitable for patients with persistent bloating, abdominal pain, diarrhoea, constipation, nausea, reflux-type symptoms or normal investigations but ongoing digestive symptoms across Oxfordshire, Buckinghamshire and surrounding areas.

Contact the secretary to arrange a consultation

Frequently Asked Questions

What is a Disorder of Gut–Brain Interaction?

A Disorder of Gut–Brain Interaction is a recognised digestive condition where symptoms arise from altered communication between the gut, nerves, immune system, microbiome and brain. The symptoms are real, even if standard tests do not show visible damage.

Is DGBI the same as IBS?

IBS is one of the commonest types of DGBI, but DGBI also includes functional dyspepsia, bloating, reflux hypersensitivity, chronic nausea, belching disorders, rumination syndrome, functional constipation and some anorectal disorders.

Does a normal colonoscopy mean my symptoms are not real?

No. A normal colonoscopy is reassuring because it helps exclude inflammation, cancer and other visible bowel disease. However, it does not measure gut sensitivity, motility, pelvic floor function or gut–brain signalling.

Can stress cause DGBI?

Stress can worsen gut symptoms, but DGBI is not simply caused by stress. Symptoms may follow infection, antibiotics, inflammation, surgery, diet change, sleep disruption or may occur without a clear trigger. The gut and brain influence each other in both directions.

Can DGBI be treated?

Yes. Treatment may include explanation, dietetic advice, bowel habit optimisation, gut sensitivity medication, gut-directed behavioural therapy, pelvic floor treatment and management of overlapping conditions such as SIBO or microscopic colitis.

Should I have more tests?

This depends on your symptoms, age, family history, blood tests, stool tests and previous investigations. The aim is to investigate when useful, but avoid repeated tests that are unlikely to change management.

Are neuromodulators antidepressants?

Some gut neuromodulators are also used as antidepressants at higher doses. In DGBI, they are usually used at lower doses to reduce gut pain, nausea, hypersensitivity or diarrhoea. This does not mean symptoms are psychological.

Is a low FODMAP diet always needed?

No. A low FODMAP diet can help selected patients, but it should usually be time-limited and ideally guided by a dietitian. Long-term restriction without reintroduction is not recommended.

Can DGBI cause weight loss?

DGBI itself does not usually directly cause significant weight loss. However, some people lose weight because they restrict food due to fear of symptoms. Unintentional weight loss should be assessed carefully.

Medical disclaimer

This webpage is intended for general patient information and education only. It is not a substitute for an individual medical consultation, diagnosis or treatment plan. Digestive symptoms can have many causes, and the most appropriate investigations or treatment will depend on your personal history, examination findings, test results, medication use and risk factors.

If you have new, severe, persistent or worsening symptoms, or symptoms such as unexplained weight loss, difficulty swallowing, vomiting blood, black stools, rectal bleeding, persistent vomiting, iron deficiency anaemia, fever, or severe abdominal pain, you should seek medical advice promptly. In an emergency, please call 999 or attend your nearest Emergency Department.

Any treatment discussed on this page should only be started, changed or stopped after discussion with an appropriately qualified healthcare professional. Dr Udit Mittal cannot provide personalised medical advice through this webpage alone.