The cause of irritable bowel syndrome is not yet fully defined and it is thought that the disease is affected by factors such as motor impairment and intestinal sensitivity, an incongruous diet and a disturbance in the transport of sensory information from the intestine to the brain. However, according to the results of research in recent years, the role of serotonin and its natural precursor is becoming increasingly important in the pathogenesis of the condition: Tryptophan.

There are now numerous tests that support serotonin as a neurotransmitter capable of improving and regulating intestinal contractility.

In 2004, at the department of gastroenterology of the Mayo Clinic College in Scottsdale, in the United States, an assessment of the role of serotonin in irritable bowel syndrome was performed: "From the literature it emerges that behind the irritable colon there is an alteration of the forward signs. and return between brain and intestine and that this alteration may be responsible for the disorders of secretion and motility typical of the syndrome "premised Michael Crowell, the author of the work.

Following a more experimental approach, two New York researchers from Columbia University came to the same conclusion: "It is very likely that there is a disturbance of the action of serotonin in the irritable bowel syndrome, because we have observed that the tegaserod, a Serotonin antagonist successfully used in chronic constipation and irritable colon, increases the number and growth of gastrointestinal neurons in culture by creating a neuroprotective and neurotorphic effect, "explain Mark Gershon and Mary Liu at the end of the results analysis.

The step towards the therapeutic exploitation of these findings was brief and involved tryptophan, the amino acid precursor of serotonin. Researchers at the University of Ankara, Turkey, have demonstrated that tryptophan administration increases serotonin levels and improves bowel motility in the experimental animal. "It is true, our experiments have shown that tryptophan optimizes peristalsis at the ileal level and contributes to the control of oxidative phenomena at the level of intestinal mucosa, "commented Daniel Ergogan, research coordinator.

The definitive confirmation of the efficacy of tryptophan in improving irritable bowel symptoms came from the department of gastroenterology in Turin. Here the researchers set up a case-control study that involved a total of 65 subjects. The intervention group consisted of 37 subjects with signs and symptoms compatible with an active irritable bowel syndrome. They were given a compound based on tryptophan, vegetable carbon, vitamins and intestinal probiotics. The effect of administration was compared to 27 controls. After the planned follow-up period it was found that both abdominal pain and constipation and diarrhea decreased significantly in the group treated with tryptophan, plant carbon, vitamins and probiotics.


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Gershon MD, Liu MT, Serotonin and neuroprotection in functional bowel disorder, Neurogastroenterol Motil 2007; 19: 19-24

Ozer C, Gonul B, Ercan ZS, Take G, erdogan D, The effectof tryptophan administration on ileum contractility and oxidant status in mice, amine Acid 2007; 23: 453-58

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