Turkey meat in the diet helped with colitis

Thanksgiving, Christmas and New Year's Day are traditionally accompanied by large feasts. For people with inflammatory bowel disease, such as ulcerative colitis, this can bring a lot of problems. For them, scientists have compiled a list of products that can reduce the risk of exacerbation.

Globally, 6.8 million people suffer from inflammatory bowel disease (IBD). Of these, 20-50% have to undergo surgical resection due to loss of sensitivity to existing medical treatments, posing serious health risks. 

Ulcerative colitis is a chronic inflammatory-ulcerative disease of the colonic mucosa, most commonly manifested by bloody diarrhea. Without treatment, colitis severely affects quality of life and increases the risk of cancer.

Treatment usually involves a number of medications and dietary changes. For example, doctors advise avoiding fruits and vegetables to reduce traumatization of the inflamed colonic mucosa and the severity of symptoms. 

Since ulcerative colitis is caused by inflammation of the inner lining of the colon and rectum, doctors from Thomas Jefferson University (USA) were looking for ways to "cool" this tissue. They studied the effect of L-tryptophan (L-Trp) - a common food component - on the response of intestinal T-cells. The foods most rich in tryptophan are turkey, cheese, fish, cottage cheese, sesame, pine nuts, milk, and yogurt. The results are published in the journal Nature Communications.

The researchers focused on T regulatory cells (Treg, regulatory T lymphocytes, T suppressors), the central regulators of the immune response. If they could get more T cells into the colon, they might be able to reduce the inflammation that causes colitis.

The scientists found a specific receptor on the surface of the T cells that acts as a magnet for the colon, GPR15. They looked for molecules that could make the cells produce more GPR15 to increase the power of the "magnet." Turns out tryptophan (or one of the molecules that tryptophan is broken down into in the body) can increase the amount of GPR15.

To see if these molecules could help with colitis, researchers added tryptophan to the diet of mice for two weeks. They observed a doubling of the number of inflammation-suppressing T cells in the colon tissue compared to mice that were not given extra tryptophan.

The team also noticed a lessening of colitis symptoms in the mice. This effect lasted for at least a week after eliminating tryptophan from the diet. According to the authors, that's about a month in "human time."

However, when tryptophan was given to mice during an exacerbation of colitis, there was little benefit. So, dietary changes are only effective in preventing future exacerbations, not treating them.

In the future, the researchers plan to see if these findings can be applied to people with colitis. Tryptophan supplementation is considered safe if the dose does not exceed 100 milligrams per day. Taking the data on mice as a benchmark, the authors expect that 100 milligrams will be enough to see an effect on patients.