Discovering the Nutrition-Microbiota Interplay in Inflammatory Bowel Disease: Are We There Yet?

Inflammatory bowel disease (IBD) is a set of chronic inflammatory disorders affecting the gastrointestinal tract, occurring in a relapsing-remitting fashion, and requiring lifelong treatments. Although great advancements in the IBD research field have been made, its exact etiology remains uncertain. It has been widely acknowledged that IBD represents a multifactorial disorder resulting from a complex interplay between genetic, host immune system, and environmental factors. Emerging evidence points at diet as a crucial factor in the pathogenesis and progression of IBD. A common feature of people suffering from IBD is intestinal dysbiosis, characterized by a reduction of Firmicutes, Bacteroidetes, Actinobacteria, and other beneficial commensal species and a concomitant increase of Proteobacteria and pathobionts, all together leading to loss of intestinal homeostasis. The consumption of industrialized and processed food, rich in saturated fatty acids, typical of a Western-like type of diet, has been shown to contribute to the onset of an aberrant hyperactivated mucosal immune response to commensal bacteria and impairment of the intestinal barrier integrity, thereby triggering intestinal inflammation. Conversely, the Mediterranean diet, rich in anti-inflammatory bioactive compounds, appears to be one of the most efficient dietetic regimen able to restore the host intestinal physiology. Given IBD molecular and clinical heterogeneity, we are far from establishing a universal nutritional protocol for IBD patients; however, data demonstrate that specific dietetic protocols and GM manipulation are useful as adjuvant therapies to prevent nutritional deficiencies, promote eubiosis, alleviate inflammatory symptoms, and ameliorate the clinical progression of IBD.