Prebiotics and the Human Gut Microbiota: From Breakdown Mechanisms to the Impact on Metabolic Health

Abstract

The colon harbours a dynamic and complex community of microorganisms, collectively known as the gut microbiota, which constitutes the densest microbial ecosystem in the human body. These commensal gut microbes play a key role in human health and diseases, revealing the strong potential of fine-tuning the gut microbiota to confer health benefits. In this context, dietary strategies targeting gut microbes to modulate the composition and metabolic function of microbial communities are of increasing interest. One such dietary strategy is the use of prebiotics, which are defined as substrates that are selectively utilised by host microorganisms to confer a health benefit. A better understanding of the metabolic pathways involved in the breakdown of prebiotics is essential to improve these nutritional strategies. In this review, we will present the concept of prebiotics, and focus on the main sources and nature of these components, which are mainly non-digestible polysaccharides. We will review the breakdown mechanisms of complex carbohydrates by the intestinal microbiota and present short-chain fatty acids (SCFAs) as key molecules mediating the dialogue between the intestinal microbiota and the host. Finally, we will review human studies exploring the potential of prebiotics in metabolic diseases, revealing the personalised responses to prebiotic ingestion. In conclusion, we hope that this review will be of interest to identify mechanistic factors for the optimization of prebiotic-based strategies.

Feeding Fiber-Bound Polyphenol Ingredients at Different Levels Modulates Colonic Postbiotics to Improve Gut Health in Cats

“…When the fiber bundle was added at lower levels (1%, 2%, or 4% w/w), significant increases in straight-chain SCFAs were observed with the fiber bundle added to 4%, and concentrations of several polyphenols were significantly higher with addition of any level of the fiber bundle [11]. These results may indicate positive health effects since SCFAs show several benefits to the host such as serving as an energy source, maintaining the integrity of the intestinal barrier, contributing to whole-host metabolism via fueling of hepatic biosynthesis pathways, and serving as signaling molecules [12]. However, no changes in the fecal microbiota were observed [11].…”

Pectin in Metabolic Liver Disease

“…Gut bacteria break down complex polysaccharides through the expression of a large panel of carbohydrate-active enzymes (CAZymes). Dietary fiber consumption increases the relative abundance of bacteria with CAZyme-encoding genes [ 39 , 40 ]. However, the changes in microbiota composition depend on the type of fiber used.…”

Dietary carbohydrates: Pathogenesis and potential therapeutic targets to obesity‐associated metabolic syndrome

“…It has been shown that a diet high in refined or processed starches and sugars that have lost the majority of fibers (~40% insoluble dietary fiber) and nutrition value can produce substantial swings in blood glucose and insulin levels, 23,24 proceed TG accumulation, the key driver of central obesity triggering adipocytokine dysregulation, and generation of inflammation, IR, MetS, and cardio‐metabolic complications 25,26 . On the other hand, complex CHO, that is, slowly digestible, such as whole grain, bran, as well as nondigestible and lente CHO have been shown to improve postprandial insulinemia, gut satiety peptides, gut microbiota, hyperlipidemia, lean body mass, inflammation and, ultimately, lower the prevalence of MetS and T2DM 27–30 . Recently short‐chain fatty acids (SCFAs) derived from dietary fibers have been used as potential therapeutic targets in the management of various metabolic disorders 27–31 .…”

“…25,26 On the other hand, complex CHO, that is, slowly digestible, such as whole grain, bran, as well as nondigestible and lente CHO have been shown to improve postprandial insulinemia, gut satiety peptides, gut microbiota, hyperlipidemia, lean body mass, inflammation and, ultimately, lower the prevalence of MetS and T2DM. [27][28][29][30] Recently short-chain fatty acids (SCFAs) derived from dietary fibers have been used as potential therapeutic targets in the management of various metabolic disorders. [27][28][29][30][31] For example, SCFAs (acetate, propionate, and butyrate) are the main metabolic products of gut microbiota.…”

“…[27][28][29][30] Recently short-chain fatty acids (SCFAs) derived from dietary fibers have been used as potential therapeutic targets in the management of various metabolic disorders. [27][28][29][30][31] For example, SCFAs (acetate, propionate, and butyrate) are the main metabolic products of gut microbiota. These SCFAs activate several G-proteincoupled cell surface receptors and release numerous hormones and signaling molecules such as GLP-1 and PYY, which act on adipocyte and balance energy homeostasis by increasing adipogenesis, leptin, and decreasing lipolysis.…”