Fibres and Colorectal Cancer: Clinical and Molecular Evidence

Abstract

Colorectal cancer (CRC) is one of the leading causes of mortality for cancer in industrialized countries. The link between diet and CRC is well-known, and presumably CRC is the type of cancer which is most influenced by dietary habits. In Western countries, an inadequate dietary intake of fibers is endemic, and this could be a driving factor in the increase of CRC incidence. Indeed, several epidemiologic studies have elucidated an inverse relationship between daily fiber intake and risk of CRC. Long-term prognosis in CRC survivors is also dependent on dietary fibers. Several pathogenetic mechanisms may be hypothesized. Fibers may interfere with the metabolism of bile acids, which may promote colon carcinogenesis. Further, fibers are often contained in vegetables which, in turn, contain large amounts of antioxidant agents like resveratrol, polyphenols, or phytoestrogens. Moreover, fibers can be digested by commensal flora, thus producing compounds such as butyrate, which exerts an antiproliferative effect. Finally, fibers may modulate gut microbiota, whose composition has shown to be associated with CRC onset. In this regard, dietary interventions based on high-fiber-containing diets are ongoing to prevent CRC development, especially in patients with high potential for this type of tumor. Despite the fact that outcomes are preliminary, encouraging results have been observed.

Exploring the Role of the Gut Microbiota in Colorectal Cancer Development

“…Typically found in fruits, vegetables, and whole grains, fiber accelerates intestinal peristalsis, reducing the contact time with potential cancer-causing substances [26]. Fiber can also interfere with bile acid metabolism, which has been shown to be involved in digestive carcinogenesis [27]. In addition, vegetables rich in fiber also contain significant quantities of antioxidant compounds, such as resveratrol, polyphenols, and phytoestrogens [27].…”

“…Fiber can also interfere with bile acid metabolism, which has been shown to be involved in digestive carcinogenesis [27]. In addition, vegetables rich in fiber also contain significant quantities of antioxidant compounds, such as resveratrol, polyphenols, and phytoestrogens [27]. Moreover, fiber can modulate the intestinal microbiome; the commensal flora can digest it to produce compounds like butyrate, which have an antiproliferative effect [27].…”

Bioactive Compounds of Dietary Origin and Their Influence on Colorectal Cancer as Chemoprevention

“…The combined treatment of 5-FU and resveratrol in colorectal cancer sensitizes tumor cells to 5-FU, which induces a further increase in oxidative stress related to the inhibition of the AKT and STAT3 proteins [119] known for their oncogenic potential in colorectal carcinomas [120].When resveratrol is combined with forskolin, it has phosphodiesterase 4D inhibitory effects to inhibit AKT/mTOR signaling in colorectal cancer cells [121]. In the same polyphenol family, EGCG can decrease the probability of recurrence of colorectal adenocarcinoma [122] in combination with cisplatin or oxaliplatin, evidenced by an improved therapeutic effect.…”