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Tryptophan Could Reduce Inflammation in Celiac Disease, Study Finds

turkey breast on a cutting board

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Key Takeaways

  • A new study has researchers feeling optimistic that tryptophan, an amino acid, could be the basis of new treatments for celiac disease.
  • People who have celiac disease are nine times more likely to have inflammatory bowel syndrome than people without the condition.
  • Tryptophan is not produced in the body, which means it needs to be consumed through a balanced diet. Turkey is one of the most well-known sources, but tryptophan is also found in other foods.

New research from McMaster University has found that tryptophan, an amino acid, combined with certain gut probiotics can help reduce inflammation in the digestive tracts of people with celiac disease.

Celiac disease occurs when people with certain predisposing genes consume gluten, which causes damage and inflammation to the upper lining of the small intestine. Left untreated, the condition can lead to serious health problems.

There is currently no cure for celiac disease. The standard of treatment is a strict gluten-free diet and close follow-up by healthcare professionals, including a nutritionist. These limited treatment options make the tryptophan findings especially exciting.

For their study, researchers examined the presence of low tryptophan metabolism in several groups: people with active celiac disease, people who had been following a strict gluten-free diet for at least two years, and people who did not have celiac disease.

The researchers found that tryptophan metabolism, which is aided by certain strains of gut bacteria, plays a key role in the activation of the aryl hydrocarbon receptor (AhR) pathway. This pathway is linked to protection and inflammation control of the gut lining.

People with active celiac disease were found to have low tryptophan metabolism, which led to non-stimulation of the AhR pathway and an increase in symptoms related to inflammation.

The people who were adhering to a strict diet had partial improvement in tryptophan metabolism, which made the researchers think there could be a link between gut bacteria, tryptophan metabolism, and the activation of the receptor pathway that protects the gut lining.

Elena Verdu, MD, PhD

The results of our study suggest that the pathway can be rescued if we use the right probiotic, but this will need to be tested in a clinical trial before we can recommend a strain.

— Elena Verdu, MD, PhD

Our main findings show that patients with active celiac disease have improper activation of the AhR pathway in their intestines due to decreased ability of their gut microbes to metabolize dietary tryptophan.” Elena Verdú, MD, PhD, an associate professor at McMaster University’s Farncombe Family Digestive Health Research Institute and lead researcher of the study, tells Verywell. “Because AhR is important to modulate inflammation and the gut barrier, this could mean that targeting this pathway could help control inflammation.”

The international study was funded by the Canadian Institutes of Health Research and the French Research Council, and published in Science Translational Medicine.

Link to Inflammatory Bowel Disease

Chronic inflammation in the gastrointestinal tract is a key factor in inflammatory bowel disease (IBD). According to the Centers for Disease Control and Prevention (CDC), IBD is an umbrella term that encompasses several diseases including Crohn's disease, which can affect any part of the digestive tract, and ulcerative colitis, which affects the large intestine (also known as the colon).

Verdú says that patients with celiac disease are nine times more likely than other people to have IBD. It was this statistic that led her team to investigate whether the two conditions share a common mechanism.

“One mechanism that has gained increasing interest in both IBD and metabolic syndrome is the molecules called indoles,” Verdú says. “These molecules are produced by our gut bacteria from dietary tryptophan and can lead to the activation of the AhR pathway.”

What the Findings Mean for Patients

Further research is needed before a specific treatment that combines tryptophan and probiotics could be developed. However, the findings of the new study point researchers in the right direction.

“The results of our study suggest that the pathway can be rescued if we use the right probiotic, but this will need to be tested in a clinical trial before we can recommend a strain,” Verdú says. “The good news is that we have probiotic candidates to test in the future, not blindly, but with a target in mind.”

Some healthcare professionals who treat patients with celiac disease also think the discovery could be promising. “This finding has the potential for clinical application,” Nielsen Fernandez-Becker, MD, a gastroenterologist at Stanford Health Care, tells Verywell. “We could use this as a diagnostic test for the patients that don’t respond to a gluten-free diet and strategize dietary changes to increase tryptophan intake.”

L-Tryptophan Supplements

Medical professionals do not recommend people take L-tryptophan supplements to boost their tryptophan levels. “There are some reports of side-effects and interactions with other medications if tryptophan is taken as a supplement,” Verdú says. “I do not endorse tryptophan supplement intake. It should be achieved by consuming a balanced diet."

Tryptophan and Diet

Tryptophan, an essential amino acid, is not produced by the body. Therefore, we have to consume it through our diet. Certain foods (including many that are gluten-free) are rich sources of the amino acid, including:

  • Turkey
  • Poultry
  • Chocolate
  • Cruciferous vegetables (broccoli, cauliflower, and cabbage)
  • Bananas

Elena Verdú, MD, PhD

The safest way to consume high levels of tryptophan is through a diverse and natural diet, which of course should be gluten-free for patients with celiac disease.

— Elena Verdú, MD, PhD

In the digestive tract, tryptophan is broken down by gut bacteria that have the ability to metabolize the amino acid.

When people with celiac disease need to cut gluten out of their diet, they might feel that they have more limited food choices. It's still important to consume a diet that's as well-balanced as possible—which includes getting enough tryptophan.

“Junk food has low amounts of tryptophan,” Verdú says. “The safest way to consume high levels of tryptophan is through a diverse and natural diet, which of course should be gluten-free for patients with celiac disease.”

Even if you don't have celiac disease, inflammation regulation is just one benefit of tryptophan. The amino acid is also needed for the synthesis of serotonin, melatonin, and niacin (vitamin B-3). If you have low levels of these important substances, you might experience insomnia, anxiety, and depression.

What This Means For You

If you have celiac disease, having adequate amounts of tryptophan in your diet might help reduce the inflammation in your gut that causes symptoms. That said, medical professionals do not recommend using supplements to add more tryptophan to your diet. Instead, talk to your doctor about ways to increase your levels naturally through the food you eat.

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  1. Lamas B, Hernandez-Galan L, Galipeau H, Constante M, Clarizio A, Jury J, et al. Aryl hydrocarbon receptor ligand production by the gut microbiota is decreased ini celiac disease leading to intestinal inflammation. Sci Transl Med. aba0624. doi: 10.1126/scitranslmed.aba0624

  2. Celiac Disease Foundation. What Is Celiac Disease?

  3. Celiac Disease Foundation. Treatment & Follow-Up.

  4. Centers for Disease Control and Prevention (CDC). Inflammatory Bowel Disease (IBD). Updated December 29, 2019.

  5. Mayo Clinic Laboratories. TRYPP - Clinical: Tryptophan, Plasma. Updated 2014.

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