Abstract: The influence of environmental factors such as diet, region, antibiotic treatment, supplemental probiotics and enteral nutrition on intestinal flora is also closely related to the occurrence and development of IBD. The theory of the mechanism of intestinal flora contains thousands of factors, which have impacts on every aspect of the host. Although the mechanisms of probiotics have not been explained clearly, they can stimulate mucus secretion, inhibit bacterial colonization, correct bacterial imbalances, improve barrier function, downregulate the expression of innate immune system receptors, balance the subsets of T cells, and change the expression of some genes. In addition, immunoregulation also produces short chain fatty acid and other metabolites, which are very important for the pathogensis of IBD.

Key words: inflammatory bowel disease, enteral nutrition, enterobacteriaceae