Diet, microbiota, and the mucus layer: The guardians of our health

Abstract

The intestinal tract is an ecosystem in which the resident microbiota lives in symbiosis with its host. This symbiotic relationship is key to maintaining overall health, with dietary habits of the host representing one of the main external factors shaping the microbiome-host relationship. Diets high in fiber and low in fat and sugars, as opposed to Western and high-fat diets, have been shown to have a beneficial effect on intestinal health by promoting the growth of beneficial bacteria, improve mucus barrier function and immune tolerance, while inhibiting pro-inflammatory responses and their downstream effects. On the contrary, diets low in fiber and high in fat and sugars have been associated with alterations in microbiota composition/functionality and the subsequent development of chronic diseases such as food allergies, inflammatory bowel disease, and metabolic disease. In this review, we provided an updated overview of the current understanding of the connection between diet, microbiota, and health, with a special focus on the role of Western and high-fat diets in shaping intestinal homeostasis by modulating the gut microbiota.

Keywords: Mediterranean diet; bacterial metabolites; fibers; gut health; intestinal immune system; microbiota; mucus layer; western diet.

Figure 1

The impact of dietary patterns on gut microbiota and intestinal health. A schematic overview depicting the importance of diet and dietary constituents in discriminating between a healthy (A) or an unhealthy (B) state of the gut barrier function by modulating the composition and functionality of the gut microbiota.

Figure 2

A general overview of the mucus layer in the small and large intestine. The mucus layer is a key component of the intestinal barrier. It is mainly composed of mucin glycoproteins produced and secreted by the intestinal goblet cells. The small intestine is characterized by a loose and unattached mucus layer containing antimicrobial products that limit penetration by bacteria (A), whereas the large intestine presents a dense and firmly attached mucus layer converted to a looser structure at the luminal side via endogenous proteolysis (B). AMPs, anti-microbial peptides.