Irritable bowel syndrome affects 10 to 15 percent of the U.S. population. People who suffer from this condition describe it as uncomfortable, inconvenient, unpredictable, embarrassing or even incapacitating. A fair number of these individuals have trouble identifying the factors that trigger their symptoms; many of them would be surprised to discover that their morning cup of coffee is contributing to their misery.
Definition
Irritable bowel syndrome, or IBS, is defined as the presence of abdominal discomfort and altered bowel habits in the absence of any inflammatory, mechanical, biochemical or physiologic explanation for the symptoms. Thorough evaluation of individuals who suffer from IBS typically reveals no obvious cause for their illness. Once known as "spastic colon," IBS can be accompanied by either diarrhea or constipation -- some patients alternate between the two -- and one of the hallmarks of the condition is relief of symptoms following a bowel movement.
Causes
The cause of IBS is unknown, although intestinal hypersensitivity to normal stimuli -- distention of the gut with food, for example -- may play a role. Diet, drugs, hormonal fluctuations and stress appear to influence patients' symptoms, but aggravating factors are not consistent from one patient to the next, or even for a specific patient. Many IBS sufferers -- but certainly not all -- also have anxiety disorders. Because the link between anxiety and IBS is prominent in many people, doctors often look for signs of physical or sexual abuse and probe for unresolved psychological issues when evaluating these patients.
Gut Abnormalities
Even though no distinct physical abnormalities can be found in IBS patients, there appear to be some common traits shared by affected individuals: a breakdown in the normal regulation between the gut and the central nervous system, gastrointestinal motor and sensory malfunction and, frequently, a history of persistent gut inflammation following infection.
How Coffee Affects the Gut
Coffee contains several substances, including caffeine and less-familiar chemicals like catechols and N-alkanoly-5-hydroxytriptamides, which increase stomach acid production. Increased stomach acid can lead to heartburn and increased gastric motility which, in turn, contributes to increased intestinal motility. Additionally, coffee has been shown to stimulate muscular activity in the colon, probably as a result of caffeine's stimulatory properties and more complex phenomena like the gastrocolic reflex, where stomach distention encourages colonic activity, and the "bitters effect," in which stimulation of the tongue by bitter substances triggers nervous impulses that increase intestinal motility.
Coffee Aggravates IBS
Since IBS is predominantly a disorder of bowel motility, any stimulus that alters intestinal motion could potentially increase a person's symptoms. Coffee offers just such a stimulus for a significant number of IBS patients. Whether they are predominantly troubled by diarrhea or constipation, coffee frequently magnifies sufferers' complaints. Like most medical conditions, IBS can be controlled, in part, through lifestyle changes. Avoidance of coffee is a relatively simple behavior that alleviates many patients' symptoms.
References
- American Family Physician: Treatment of Irritable Bowel Syndrome
- "The Merck Manual of Diagnosis and Therapy: Irritable Bowel Syndrome"; Mark Beers, MD, Editor-in-Chief; 2006
- Medicine Net: Coming Soon, A Low-Heartburn Coffee?
- Pub Med: Coffee and Gastrointestinal Function, Facts and Fiction
