The gut microbiome: linking dietary fiber to inflammatory diseases

Dietary fiber intake in humans is nowadays substantially decreased as compared to the communities of ancestral populations. Accompanying that, the incidences of inflammatory bowel disease (IBD), allergy, and other autoimmune diseases are steadily increasing over the past 60 years, especially in high-income countries, which is partly attributed to the changing dietary habit in modern societies. Chronic inflammation triggered by immune disorders is the central part of the pathophysiology of various non-communicable diseases. Dietary fiber intake is inexorably linked to the gut microbiome leading to the reduction of inflammation. This review explores how dietary fibers modulate the gut microbiota composition and function leading to the alteration of host physiology. High-fiber dietary regime has been consistently shown to increase the microbiome alpha diversity and short-chain fatty acids (SCFAs)-producing bacteria in the human gut. SCFAs are the main players in the interplay between diet, microbiota, and host health. In clinical settings, therapies with high fiber or SCFA supplementations are proposed for inflammatory diseases. However, due to greater variations in the dosage, type, and duration of dietary fiber intervention in different clinical trials, the effects remain controversial. Unraveling the mechanisms exerted by dietary fiber in synergy with the gut microbiome in human pathophysiology holds a promising prospect in guiding next-generation precision therapies.