Dietary fibres as “prebiotics”: Implications for colorectal cancer

Abstract

A "prebiotic" is a nondigestible food ingredient whose beneficial effects on the host result from the selective stimulation of growth and/or activity of members of the bacterial community that inhabits the human bowel (the gut microbiota). Although much of the prebiotic literature focuses on nondigestible oligosaccharides, such as oligofructose, most dietary fibres that are fermentable carbohydrates could be considered as prebiotics. Early studies suggested that colonic bacteria were risk factors for colon cancer. However, altering the composition or metabolic activity of the bowel microbiota through the use of dietary fibre might be important in reducing the prevalence of colorectal cancer. Mechanisms for beneficial effects of prebiotics might include changing the activity of exogenous carcinogens through modulating metabolic activation and/or detoxification, or stimulating the production of the short-chain fatty acid, butyrate. However, modern analytical techniques suggest that an important consequence of a modified bacterial community could be a change in the expression not only of a range of different bacterial genes in bowel contents, but also in the bowel mucosa of the host. Analogous with observations with probiotics, the stimulation of cytokines and modification of immune responses could be important in producing beneficial effects. Compared with transitory effects of probiotics, the prebiotic action of fermentable carbohydrates potentially provide the opportunity for sustainable modulation of activity of the gut microbiota. However, their mechanisms of action in humans are speculative, and research aimed at providing an integrated view of the gut microbiota and dietary fibre nutrition of humans needs to be developed.

An Overview of the Recent Developments on Fructooligosaccharide Production and Applications

“…There have been several studies on the use of prebiotics in cancer prevention mainly focusing on animal models, but the "dietary fiber hypothesis" for protection against colorectal cancer was advanced by Burkitt (1969) based on epidemiological evidence supporting a relationship between diet and colon health. These findings showed lower rates of colorectal cancer in Africa compared to industrialized Western countries, where traditional diets consisted of high amounts of unrefined fiber and high intakes of refined carbohydrates, respectively (Manning and Gibson 2004;Lim et al 2005a). …”

Probiotics, prebiotics and synbiotics: A role in chemoprevention for colorectal cancer?

“…Prebiotics are defined as, "nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one, or a limited number of bacteria in the colon, thus improving host health". 53 Common prebiotics include inulin, fructooligosaccharide, lactulose, and resistant starch. 53 Dietary fibre has also been shown to convey a prebiotic effect which has been linked to the reduction of CRC.…”

“…53 Common prebiotics include inulin, fructooligosaccharide, lactulose, and resistant starch. 53 Dietary fibre has also been shown to convey a prebiotic effect which has been linked to the reduction of CRC. 54 A meta-analysis by Friedenreich et al, 54 concluded that consumption of over 27 g of fibre per day resulted in a 50% reduction in CRC compared to consumption of less than 11 g. Young et al 43 have comprehensively reviewed the evidence for the potential benefits of dietary fibre in the reduction of CRC.…”

Chemopreventive Potential of Probiotics and Prebiotics

“…Prebiotics are produced either by extraction from natural sources or by chemical synthesis [59] [60]. Most common prebiotics are inulin, fructooligosaccharide, lactulose, and resistant starch [61] [62].…”