Insoluble dietary fibers: structure, metabolism, interactions with human microbiome, and role in gut homeostasis

Abstract

Consumption of food rich in dietary fibers (DFs) has been long recognized to exert an overall beneficial effect on human health. This review aims to provide a holistic overview on how IDFs impact human gut health either directly, or through modulation of the gut microbiome. Several databases were searched for collecting papers such as PubMed, Google Scholar, Web of Science, Scopus and Reaxys from 2000 till 2022. Firstly, an overview of the chemical structure of the various IDFs and the pathways employed by gut microbiota for their degradation is provided. The impact of IDFs on microbial community structure and pathogens colonization inside the human gut was discussed. Finally, the impact of IDFs on gut homeostasis and systemic effects at the cellular level, as well as the overall immunological benefits of IDFs consumption were analyzed. IDFs viz., cellulose, hemicellulose, resistant starch, and lignin found enriched in food are discussed for these effects. IDFs were found to induce gut immunity, improve intestinal integrity and mucosal proliferation, and favor adhesion of probiotics and hence improve human health. Also, IDFs were concluded to improve the bioavailability of plant polyphenols and improve their health-related functional roles. Ultimately, dietary fibers processing by modification shows potential to enhance fibers-based functional food production, in addition to increase the economic value and usage of food-rich fibers and their by-products.

Keywords:

• Cellulose
• gut homeostasis
• gut microbiota
• insoluble dietary fibers
• SCFA

Acknowledgements

Dr. Mohamed Farag acknowledges the Alexander von Humboldt foundation, Germany.

Author contributions

Mohamed Salah and Nada Ezzelarab: data collection and writing—original draft. Mostafa H. Baky: writing—review and editing. Ping Shao, Mostafa S. Elshahed: review and editing. Mohamed A. Farag: supervision, conceptualization, investigation, and writing—review and editing.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

No funding was received for this article. Work in Mostafa Elshahed laboratory has been supported by the National Science Foundation Grant 2016423..