Functional Gastrointestinal Disorder

Functional gastrointestinal disorders affect approximately 40% of people worldwide, causing chronic digestive symptoms despite the absence of visible structural problems. These conditions, now increasingly understood as disorders of gut-brain interaction, significantly impact quality of life but can be effectively managed through a combination of lifestyle changes, dietary modifications, and medical treatment.

Table of contents

• What Are Functional Gastrointestinal Disorders?
• Alternative Names
• Types and Classification
• What Causes These Disorders?
• Common Symptoms
• How Common Are These Disorders?
• How Are These Disorders Diagnosed?
• Treatment Approaches
• Living with Functional Gastrointestinal Disorders

What Are Functional Gastrointestinal Disorders?

Functional gastrointestinal disorders, also known as disorders of gut-brain interaction, are a group of conditions that affect different parts of the digestive system^[1]. These disorders cause ongoing digestive symptoms even though doctors cannot find any structural damage or disease when they examine the digestive tract^[2].

The term “functional” describes disorders where the body’s normal activities are impaired^[1]. In the past, these conditions were thought to have no organic basis, but our understanding has evolved. We now know that functional gastrointestinal disorders arise from problems in how the brain and gut communicate with each other^[3].

These disorders are defined by gastrointestinal symptoms related to any combination of several factors: movement problems in the digestive tract (motility disturbance), increased sensitivity to sensations from the gut (visceral hypersensitivity), changes in the gut’s protective lining and immune function, alterations in gut bacteria, and changes in how the central nervous system (brain and spinal cord) processes signals from the digestive system^[2].

Disorders of gut-brain interaction, Functional bowel disorder, Functional colonic disease, FGID

Types and Classification

The Rome Foundation has developed a classification system called Rome IV, published in 2016, which organizes functional gastrointestinal disorders into different groups. This system includes 33 adult disorders and 20 pediatric disorders^[3][4].

The classification divides these disorders based on which part of the digestive system is affected. Esophageal disorders include conditions like functional chest pain, functional heartburn, and difficulty swallowing. Gastroduodenal disorders affect the stomach and upper small intestine and include functional indigestion, excessive belching, chronic nausea and vomiting, and cyclic vomiting syndrome^[2].

Bowel disorders represent the most common group and include irritable bowel syndrome, functional constipation, functional diarrhea, and functional abdominal bloating. Irritable bowel syndrome is one of the most common forms and is estimated to affect 1 out of 7 adults in the United States^[5]. This condition is characterized by ongoing or returning abdominal pain or discomfort associated with changes in bowel habits, with no evidence of an organic disorder such as an ulcer or blockage^[5].

Additional categories include centrally mediated disorders of gastrointestinal pain, gallbladder and sphincter of Oddi disorders, and anorectal disorders such as fecal incontinence and functional anorectal pain^[2].

What Causes These Disorders?

Functional gastrointestinal disorders develop from a complex interaction of multiple factors. These conditions are caused by problems in how the digestive system functions, including changes in gut sensitivity, movement of food through the digestive tract, the community of bacteria living in the gut (the microbiota), immune system functioning, and how the brain and central nervous system process signals from the gut^[3].

Some causes are within a person’s control, such as stress and smoking, which can be greatly affected by lifestyle changes. However, there are many causes that people cannot control. These include family history, increased sensitivity in the gut, digestive movements that are too fast or too slow, how the immune system functions, and how the central nervous system processes information^[4].

The brain-gut axis plays a crucial role in these disorders. The gut and the brain influence each other significantly. Stress, depression, or other psychological factors can affect movement and contractions of the gastrointestinal tract, as well as sensations perceived to come from the gut. Research also suggests that some people with functional gastrointestinal disorders perceive pain more intensely than other people because their brains do not properly regulate pain signals from the digestive tract^[19].

In many individuals with these disorders, particularly irritable bowel syndrome, symptoms begin or worsen after eating a meal. People with diarrhea-predominant irritable bowel syndrome experience an exaggerated response to food ingestion that causes pain after eating and urgent need to have a bowel movement. Although people with these disorders do not commonly have true food allergies, sensitivities to foods are reported by nearly half of patients^[5].

Common Symptoms

Functional gastrointestinal disorders cause ongoing symptoms throughout the digestive tract. Physical symptoms can vary depending on the specific condition but commonly include abdominal pain, bloating, burping, constipation, diarrhea, flatulence, indigestion, nausea, swallowing difficulties, and vomiting^[4][3].

The two most common types have distinct symptom patterns. Irritable bowel syndrome causes abdominal discomfort, altered bowel habits, and bloating. Functional dyspepsia causes pain or discomfort in the upper abdomen, often related to eating, which can be associated with feelings of fullness and early satiety (feeling full quickly when eating)^[3].

These symptoms are made worse by unhelpful patient behaviors, stress, and psychological conditions occurring alongside the digestive disorder^[3]. Research has found a strong link between mental health conditions and functional gastrointestinal disorders. Stress, anxiety, and depression can be symptoms of the disorder itself, and they can also worsen digestive symptoms^[4].

In children, the most common symptom is functional abdominal pain. This means pain that comes from atypical function of the digestive system rather than from an illness^[4].

How Common Are These Disorders?

Functional gastrointestinal disorders are very common throughout the world. Approximately 40% of people globally live with these conditions, and they are more common in women than in men. The prevalence of these disorders decreases with age^[3][4].

In terms of healthcare impact, these disorders account for 12% of the workload in primary care and 30% of gastroenterology outpatient consultations^[3]. More than two-thirds of patients with functional gastrointestinal disorders will have seen a doctor in the last 12 months, and 40% will use regular medication^[3].

These conditions pose a huge economic burden on healthcare systems. In the United Kingdom’s National Health Service, treating them cost at least £72.3 million in the year 2014/2015, of which two-thirds was spent on prescriptions, community care, and hospital treatment^[3]. The disorders have a significant negative impact on quality of life, work productivity, and health care costs^[5].

How Are These Disorders Diagnosed?

Functional gastrointestinal disorders are diagnosed based on ongoing gastrointestinal symptoms in the absence of visible problems on conventional testing. When doctors examine the digestive tract or perform tests such as bloodwork, X-rays, or endoscopy, they do not find evidence of an organic disorder, structural abnormality, or another cause for chronic digestive symptoms^[5][3].

The diagnosis relies on recognizing patterns of symptoms and ruling out other conditions that could cause similar problems. Healthcare providers use the Rome IV diagnostic criteria, which provide specific definitions for each type of functional gastrointestinal disorder^[2].

Patients can help their doctors by keeping a food diary. Writing down what you eat can help identify which foods cause problems. This is especially helpful for disorders such as irritable bowel syndrome and Crohn’s disease, for which certain foods can trigger or worsen symptoms. A food diary is also a key part of diagnosing food sensitivities. Record how much you consume and at what time, write down what symptoms you have and when they occur, and share this information with your healthcare provider^[18].

Treatment Approaches

Management of functional gastrointestinal disorders involves a biopsychosocial approach, meaning it addresses biological, psychological, and social factors. This includes changes in lifestyle and diet, addressing coexisting psychological conditions, and using medication to treat the underlying problems in how the digestive system functions^[3].

Medication

Several types of medications can be effective for functional gastrointestinal disorders. Antispasmodics help reduce muscle spasms in the digestive tract. Neuromodulators help change how pain signals are processed. Motility agents help improve movement through the digestive system. Antidepressants can be effective not only for treating depression that may accompany these disorders but also for reducing pain and improving digestive function^[3].

New drugs for functional bowel disorders target key mechanisms in how these disorders develop. Unlike older treatments that mainly affect one symptom, these newer medications improve both abnormal bowel habits and other key symptoms such as abdominal pain and bloating^[10].

Dietary Changes

Dietary modifications play a crucial role in managing functional gastrointestinal disorders and can significantly reduce symptoms for many people. Identifying and avoiding specific food triggers is essential, as certain foods and beverages can worsen symptoms like bloating, abdominal pain, and altered bowel habits^[13].

A well-balanced diet that emphasizes whole, unprocessed foods while minimizing artificial additives can contribute to better digestive health. Adopting a diet rich in fiber can improve bowel regularity, although it is important to increase fiber intake gradually to avoid further digestive discomfort^[13].

The Low FODMAP diet is one of the most commonly recommended dietary approaches for managing irritable bowel syndrome. This diet reduces intake of certain types of carbohydrates that are poorly absorbed in the small intestine, known as fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs). By initially eliminating high-FODMAP foods such as wheat, certain fruits, dairy products, and legumes, individuals can identify specific triggers contributing to their symptoms^[15].

Psychological Treatment

Psychotherapy in motivated individuals is equally effective as medication. Because stress and psychological factors can make symptoms worse, addressing these aspects is an important part of treatment^[3].

Stress management techniques such as cognitive-behavioral therapy can help individuals identify and change negative thought patterns that contribute to anxiety and stress, thereby reducing their impact on gastrointestinal symptoms. Mindfulness and meditation practices are also effective because they promote relaxation and can enhance ability to cope with stressful situations^[15].

One review of 32 studies showed that people treated with psychologically based approaches had greater improvement in their symptoms compared with people who received conventional medical treatment alone^[19].

Living with Functional Gastrointestinal Disorders

Several lifestyle changes can help manage functional gastrointestinal disorders effectively. The success of treatment is increased by a good relationship between doctor and patient, so this needs to be taken into account during consultations^[3].

Physical Activity

Regular physical activity benefits individuals with functional gastrointestinal disorders. Exercise can enhance intestinal movement, reduce symptoms such as bloating and abdominal discomfort, and reduce stress, which is often a trigger for flare-ups. It is recommended that individuals aim for at least 150 minutes of moderate-intensity aerobic activity each week, such as brisk walking, cycling, or swimming^[15][13].

Low-impact activities like yoga can be particularly beneficial because they promote relaxation and core stability while being gentle on the digestive system. It is essential to listen to your body and choose activities that feel comfortable, adjusting the intensity and duration based on personal capabilities and symptom patterns^[15].

Stress Management

Managing stress is crucial because stress can worsen symptoms. Techniques include deep breathing, meditation, and relaxation exercises. These practices help cultivate a deeper understanding of thoughts and emotions, fostering a healthier mindset^[15].

Sleep

Good sleep habits are vital for maintaining gastrointestinal function. Poor sleep quality can lead to increased stress levels and heightened sensitivity to gastrointestinal discomfort. Establishing a consistent sleep routine, creating a restful sleeping environment, and limiting screen time before bed can promote better sleep, ultimately supporting gastrointestinal health^[15].

Smoking

Smoking weakens the muscle that keeps stomach acid from backing up into the esophagus, increasing the risk for heartburn and GERD. Smoking also worsens symptoms of Crohn’s disease and damages the liver’s ability to process medications. Stopping smoking can help improve symptoms^[18].

Hydration

Staying well-hydrated is vital for digestive health. Adequate fluid intake supports overall body functions and can help soften stool, which is beneficial for those experiencing constipation^[15].