Diet-Microbiota Interactions in Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Although the precise etiology of IBD is largely unknown, it is widely thought that diet contributes to the development of IBD. Diet shapes the composition of the gut microbiota, which plays critical roles in intestinal homeostasis. In contrast, intestinal inflammation induces gut dysbiosis and may affect the use of dietary nutrients by host cells and the gut microbiota. The interaction of diet and the gut microbiota is perturbed in patients with IBD. Herein, we review the current knowledge of diet and gut microbiota interaction in intestinal homeostasis. We also discuss alterations of diet and gut microbiota interaction that influence the outcome and the nutritional treatment of IBD. Understanding the complex relationships between diet and the gut microbiota provides crucial insight into the pathogenesis of IBD and advances the development of new therapeutic approaches.

Keywords: diet–microbiota interactions; gut microbiota; inflammatory bowel disease (IBD); metabolic reprogramming; precision nutrition.

Figure 1

The roles of nutrients and foods in the pathogenesis of inflammatory bowel disease (IBD). Epidemiological, clinical, and animal studies have demonstrated that certain components of diet are associated with IBD. Diet plays a critical role in intestinal homeostasis, including the gut microbiota, intestinal mucosal barrier, and mucosal immune system. Diet directly modulates the mucosal barrier and immunity, whereas diet–microbiota interaction also regulates the intestinal homeostasis.

Figure 2

Functional changes in the gut microbiota in IBD. The gut microbiota produces short-chain fatty acids (SCFAs) and vitamins and deconjugates bile acids, which play crucial roles in mucosal barrier and immunity. In patients with IBD, decreased α-diversity, reduced abundance of beneficial bacteria and metabolites, and increased pathobionts are the common features of gut dysbiosis. Gut dysbiosis is accompanied by functional alteration of the gut microbiota. In particular, decreased SCFA production, bile acid metabolism, and vitamin production in the gut microbiota in IBD are associated with impaired mucosal barrier integrity and abnormal immune reactions, resulting in intestinal inflammation.

Figure 3

The roles of diet–microbe interaction in intestinal homeostasis and inflammation. The gut microbiota produces various metabolites from dietary components that exert important and diverse effects on intestinal homeostasis, including the maintenance of the epithelial barrier and mucosal immunity. In contrast, gut inflammation or mutation of certain genes change microbial composition and function, decreasing the production of beneficial microbial metabolites, such as SCFAs and indole derivatives. In addition, inflammation-induced metabolic reprogramming of adherent and invasive Escherichia coli (AIEC) enables it to adapt to the inflamed gut and to compete with commensal E. coli (CEC). Westernized diet, characterized by high saturated fat and emulsifiers, promotes blooms of certain pathobionts, some of which impair the epithelial barrier and stimulate a proinflammatory response.