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The Role of Tryptophan in IBS

I’ve been writing a lot lately about the brain-gut axis, and the role the brain can play in IBS. More specifically, I have also been looking at how serotonin, which affects mood, also affects IBS. But here’s something I’ve stumbled upon recently in my readings: Serotonin (which is a hormone) is dependent on an essential amino acid called “L-Tryptophan.” The problem is humans do not produce this amino acid in our bodies on our own and are not capable of doing so.

What types of food have tryptophan?

Tryptophan is found in many foods, however – especially those high in protein such as cheese, beef, liver, lamb, fish, nuts, oatmeal and turkey. In fact, if the name “tryptophan” sounds familiar to you, it’s probably been in the context of jokes about how on Thanksgiving people are often exhausted after eating their turkey dinners. It’s the tryptophan that supposedly leads to this sleepy, contended feeling as it helps produce serotonin. Or at least, that’s the simplified understanding and narrative of how it is thought to work.

I’ve been vegetarian for a long time, so I am no longer eating turkey or any other kind of animal, though I do still eat eggs and dairy, and lots of none-animal protein sources like nuts and oatmeal. Yet people who are worried they are deficient in tryptophan can find them in supplement forms at many health food stores or online. Though it’s advised to check with a doctor as they may interfere with some prescription medications (such as SSRI-type anti-depressants) or not recommended to people with certain health disorders.

Research on tryptophan and IBS

Because tryptophan is essential to the production of serotonin and serotonin plays a key role in mind-gut axis, and therefore, impacts IBS – as some researchers have asserted, “IBS may be related to disrupted tryptophan metabolism…” 1 Tryptophan also acts as fuel for the beneficial bacteria Lactobacillus in the body, which may also account for why probiotics not only account for improvements in IBS in some patients but a better sense of mental well-being.

Another study noted that “Irritable bowel syndrome (IBS) has been linked with abnormal serotonin functioning and immune activation. Tryptophan forms the substrate for serotonin biosynthesis.”2

Should I increase tryptophan in my diet to help with IBS?

So does this mean that simply increasing tryptophan in one’s diet or supplementing with it, can assuage IBS? It’s unclear.

While tryptophan definitely plays a role in all of it, some studies have had mixed results about whether dietary changes that boosted intake of tryptophan had any significant positive impacts in IBS patients. That being said, unless you have food allergies or sensitives that prevent you from doing so, it probably couldn’t hurt to up your protein and thereby, intake of L-tryptophan. And if your medical professional feels it’s okay and compatible with your health profile, you can also try supplementing with it some to see if it benefits your IBS. Nevertheless, it’s interesting to learn more about how different amino acids and other substances in the body or found in food effects the body and brain and related to that, disorders like IBS.

Have you ever supplemented with L-Tryptophan? Did you experience any changes to your IBS symptoms? Please share in the comments below!

This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

  1. Berstad A, Raa J, Valeur J. Tryptophan: ‘essential’ for the pathogenesis of irritable bowel syndrome? Scand J Gastroenterol. 2014 Dec; 49(12):1493-1498. . Accessed September 5, 2019.
  2. Fitzgerald P, Cassidy EM, Clarke G, et al. Tryptophan catabolism in females with irritable bowel syndrome: relationship to interferon-gamma, severity of symptoms and psychiatric co-morbidity. Neurogastroenterol Motil. 2008 Dec;20(12):1291-7. Accessed: September 5, 2019.