Immunity and Nutrition: The Right Balance in Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD) is an increasingly urgent medical problem that strongly impairs quality of life for patients. A global rise in incidence has been observed over the last few decades, with the highest incidence rates recorded in North America and Europe. Still, an increased incidence has been reported in the last ten years in newly industrialized countries in Asia, including China and India, both with more than one billion inhabitants. These data underline that IBD is an urgent global health problem. In addition, it is estimated that between 20% and 30% of IBD patients will develop colorectal cancer (CRC) within their lifetime and CRC mortality is approximately 50% amongst IBD patients. Although the exact etiology of IBD is still being defined, it is thought to be due to a complex interaction between many factors, including defects in the innate and adaptive immune system; microbial dysbiosis, i.e., abnormal levels of, or abnormal response to, the gastrointestinal microbiome; a genetic predisposition; and several environmental factors. At present, however, it is not fully understood which of these factors are the initiators of inflammation and which are compounders. The purpose of this review is to analyze the complex balance that exists between these elements to maintain intestinal homeostasis and prevent IBD or limit adverse effects on people's health.

Keywords: cytokines; dysbiosis; immune bowel disease; polyunsaturated fatty acids.

Figure 1

Immune mechanisms involved in the pathogenesis of IBD. (A) Diet can affect both microbiota and innate immune cells phenotype toward pro-inflammatory conditions. (B) One’s genetic background can make the onset of inflammationmore likely. (C) Diet can affect trained immunity of innate cells. (D) Gut immune homeostasis depends on the balance between regulatory Tcells and helper T cells. (E) Altered signaling between innate and adaptive immunity can shift this balance toward chronic activation of the immune system. (F) Cytokines, produced by Th cells, can activate ILC cells, which contribute to sustaining chronic inflammation. Adapted from “Intestinal Immune System”, by BioRender.com (2022). Retrieved from https://app.biorender.com/biorender-templates (accessed on 17 January 2022).

Figure 2

Nutrition is critical to the development and progression of IBD. Eating habits influence the risk of IBD through numerous and complex mechanisms affecting the intestinal microbiota and leading to the inflammation of the intestine. Thus, causing deregulated immune responses that worsen the prognosis of IBD.