The Role of Prebiotics in Modulating Gut Microbiota: Implications for Human Health

Abstract

The human gut microbiota, an intricate ecosystem within the gastrointestinal tract, plays a pivotal role in health and disease. Prebiotics, non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of beneficial microorganisms, have emerged as a key modulator of this complex microbial community. This review article explores the evolution of the prebiotic concept, delineates various types of prebiotics, including fructans, galactooligosaccharides, xylooligosaccharides, chitooligosaccharides, lactulose, resistant starch, and polyphenols, and elucidates their impact on the gut microbiota composition. We delve into the mechanisms through which prebiotics exert their effects, particularly focusing on producing short-chain fatty acids and modulating the gut microbiota towards a health-promoting composition. The implications of prebiotics on human health are extensively reviewed, focusing on conditions such as obesity, inflammatory bowel disease, immune function, and mental health. The review further discusses the emerging concept of synbiotics-combinations of prebiotics and probiotics that synergistically enhance gut health-and highlights the market potential of prebiotics in response to a growing demand for functional foods. By consolidating current knowledge and identifying areas for future research, this review aims to enhance understanding of prebiotics' role in health and disease, underscoring their importance in maintaining a healthy gut microbiome and overall well-being.

Keywords: human health; intestinal microbiota; microbiota; prebiotics.

Figure 1

Chemical structures of fructans. Differences in fructans structures arise based on the position of fructose addition, leading to the creation of (A) 1-kestose (B) 6-kestose (C) 6G-kestose.

Figure 2

Effects of prebiotics. Fructans (inulin and fructooligosaccharides) improve gastrointestinal health, enhance mineral absorption, and lower blood lipids. Lactulose lowers intestinal pH and increases fecal biomass. Resistant starch prevents colorectal cancer and promotes beneficial bacteria. Galactooligosaccharides increase immune responses and beneficial microorganisms. Xylooligosaccharides lower glucose and cholesterol, improve mineral absorption, and stimulate immunity. Polyphenols reduce inflammation and the risk of inflammatory bowel disease.

Figure 3

Chemical structures of fructooligosaccharides (FOS). FOS is a series of homologous oligosaccharides derived from sucrose, usually denoted by the chemical formula GFn: (A) 1-kestose (GF2); (B) nystose (GF3); (C) 1^F-β-fructofuranosyl nystose (GF4).

Figure 4

Chemical structures of other types of prebiotics. (A) Galactooligosaccharides (GOS) are non-digestible carbohydrates composed of 3–10 or more galactose molecules and a terminal glucose molecule. (B) Xylooligosaccharides (XOS) are linear oligosaccharides composed of d-xylose units linked by β-1, 4 glycosidic bonds. (C) Chitooligosaccharides (COS) are chitosan oligomers formed by the hydrolysis of chitosan. (D) Lactulose is produced through the isomerization of lactose. (E) Polyphenols are characterized by an aromatic ring containing one or more hydroxyl groups in their chemical structure.

Figure 5

Lactulose Metabolism and Effects as Prebiotics. Lactulose is selectively metabolized by Bifidobacteria and Lactobacilli in the colon and has health effects through metabolites.