New York, Aug 5: Consuming protein rich foods such as nuts, eggs, seeds, beans, poultry, yogurt, cheese and even chocolates may foster a more tolerant and less inflammatory gut environment, which could mean relief for people living with abdominal pain and diarrhoea of inflammatory bowel disease, a study has said. These food items contain an appreciable amounts of tryptophan -- an amino acid used in the buildup of proteins -- which when fed on mice led to the development of immune cells that foster a tolerant gut, the study said. The findings indicated that a protein rich diet triggers the appearance of immune cells in Lactobacillus reuteri (L. reuteri) -- a bacterium that normally lives in the gut, and together these promote a more tolerant, less inflammatory gut immune system. "We established a link between one bacterial species -- Lactobacillus reuteri -- that is a normal part of the gut microbiome, and development of a population of cells that promote tolerance," said Marco Colonna, the Robert Rock Belliveau, Professor at the Washington University School of Medicine in St.Louis. "The more tryptophan the mice had in their diet, the more of these immune cells they had," Belliveau added. For the study, published in the journal Science, the team examined mice that had lived under sterile conditions since birth and was germ-free. When L. reuteri was introduced to these mice, the immune cells arose. Further, when tryptophan was doubled in the mice's feed, the number of such cells rose by about 50 per cent. Humans have the same tolerance-promoting cells as mice, and have L. reuteri in the gastrointestinal tracts. "The development of these cells is probably something we want to encourage since these cells control inflammation on the inner surface of the intestines," explained Luisa Cervantes-Barragan, Postdoctoral researcher from the varsity. "High levels of tryptophan in the presence of L. reuteri may induce expansion of this population," Cervantes-Barragan said.