Digestive problems and irritable bowel syndrome (IBS) frequently accompany FM. Abdominal pain, bloating, and discomfort are the main symptoms of IBS. Some people also experience constipation; others have chronic diarrhea; and some alternate between constipation and diarrhea.
Researchers have not yet discovered a specific cause for IBS. Below are some of the possibilities that might explain its relationship to FM:
- One theory is that people who suffer from IBS have a colon, or large intestine, that is particularly sensitive and reactive to certain foods and stress. Since FM tends to involve general hypersensitivity, it follows that they could have a sensitive digestive tract.
- Normal motility, or movement, may not be present in the colon of a person who has IBS. Staying active and exercising regularly can help the colon maintain its natural motility, but people with FM tend to be less active and often shy away from exercise because of the pain.
- According to the National Institutes of Health, “Recent research has reported that serotonin is linked with normal gastrointestinal (GI) functioning. Serotonin is a neurotransmitter, or chemical, that delivers messages from one part of your body to another. Ninety-five percent of the serotonin in your body is located in the GI tract, and the other 5 per cent is found in the brain. Cells that line the inside of the bowel work as transporters and carry the serotonin out of the GI tract. People with IBS, however, have diminished receptor activity, causing abnormal levels of serotonin to exist in the GI tract. As a result, they experience problems with bowel movement, motility, and sensation – having more sensitive pain receptors in their GI tract.” Since people with FM are known to have lower than normal levels of serotonin, this could be a significant factor.