Functional bowel disorders (FBD) are exactly what it means: a disorder that involves abnormal function of the gastrointestinal tract, particularly the small and large bowel. These are classified by a 5 categories:
Irritable Bowel Syndrome (IBS)
Functional abdominal bloating/distention
Unspecified functional bowel disorder
Currently, these conditions do not have a diagnostic tool and therefore requires a thorough exclusion of more serious gut issues such as Inflammatory Bowel Disease, Bowel Cancer before it can be diagnosed. FBD is considered a chronic condition, therefore symptoms must have been present for more than 6 months and three or more days a month in the last 3 months.
Our Digestive System
Our digestive system consists of a series of organs to facilitate digestion of the food we eat. A part of this is our gastrointestinal tract, involving our mouth, oesophagus, stomach, small intestine, large intestine, and anus. Food passes through these organs to be digested, absorb nutrients and excrete waste. Indigestible food make their way to the intestines, where it becomes fermented to nourish the gut microbiota. The by-products produced in the fermentation process are absorbed by the bacteria host.
If you have FBD, this means your gastrointestinal tract is not functioning at a 'normal' level. The concept and diagnosis of FBD continues to be an area that requires further research and understanding. However, there are many approaches to help reduce symptom severity, often medications but dietary strategies can also play a role.
Functional Bowel Disorders Longstreth, George F. et al. Gastroenterology, Volume 130, Issue 5, 1480 - 1491