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‘Love potion’ makes bowel tolerant to bacteria

Researchers from Erasmus MC's department of Gastroenterology have discovered that the intestinal immune system produces a substance that sees to it that the billions of bacteria living in the intestines are nurtured there 'lovingly'.

An article on this biochemical process will feature in the latest edition of the leading scientific journal Immunity that will be published today, which is Valentine's Day.


In the article, Maikel Peppelenbosch, head of the Gastroenterology laboratory, explains that the breakdown of the amino acid tryptophan releases a substance that tells the immune system to tolerate the intestinal bacteria. "One of the products of tryptophan degradation is kynurenine, and this appears to work like a love potion for the immune system's dendritic cells. Under the influence of kynurenine, these cells release a message telling the immune system not to bother the intestinal cells.

Tryptophan is one of the substances the body needs to produce the tens of thousands of different proteins in the body. These are in turn necessary for the development of numerous cell types. Tryptophan is found in foods such as meat, bananas, bread, and cheese. Processed meats such as dry-cured salami also contain high levels of tryptophan. The degradation of tryptophan triggers the release of serotonin in the brain. Serotonin has long been known as a 'love hormone'.

The discovery of the effect of the 'love substance' in the bowel could be a step forward in the treatment of people with bowel disorders such as Crohn's Disease and Ulcerative Colitis. But also for the many patients with Irritable Bowel Syndrome, a condition that is often misunderstood. These patients' immune system responds too aggressively to the intestinal flora.

Irritable Bowel Syndrome is a major problem in the Netherlands. Estimates vary, but it is thought that between five and twenty percent of the Dutch population suffers from this disorder to a greater or lesser degree. "We had already noticed that people with Irritable Bowel Syndrome eat products such as dried sausages relatively often," says Peppelenbosch. "Perhaps this shows that these patients have a natural need for more tryptophan because its degradation releases kynurenine."

For most patients, the cause of Irritable Bowel Syndrome is not fully understood. "At one time the syndrome was viewed as being 'all in the mind', particularly as the bowel is known to be very sensitive to stress. But this discovery seems to prove that it is indeed in the bowel and not the mind.

Press the button 'ondertiteling' in the lower bar of the video to activate the subtitles.

Read the full press release.

Date published: 14 February 2017.

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