DIETARY FIBER INTAKE IN COLORECTAL CANCER PREVENTION: EPIDEMIOLOGICAL EVIDENCE, MICROBIOTA-MEDIATED MECHANISMS, AND DIETARY PATTERN INTERACTIONS—A NARRATIVE REVIEW

Abstract

Background: Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality worldwide. Increasing evidence suggests that dietary factors, particularly dietary fiber intake, may play an important role in CRC prevention through modulation of gut microbiota, short-chain fatty acid production, inflammation, and intestinal homeostasis. Aim: The aim of this review was to critically evaluate current epidemiological and mechanistic evidence regarding the association between dietary fiber intake and colorectal cancer risk. Material and methods: A narrative review of the literature was conducted based on epidemiological studies, prospective cohort studies, meta-analyses, umbrella reviews, and experimental studies investigating the relationship between dietary fiber and colorectal cancer. Particular attention was given to different fiber types, biological mechanisms, gut microbiota interactions, and public health implications. Results: The majority of epidemiological studies demonstrate an inverse association between dietary fiber intake and colorectal cancer risk, with the strongest protective effects observed for cereal and whole-grain fiber. Proposed mechanisms include increased production of short-chain fatty acids, modulation of gut microbiota, reduction of chronic inflammation, improved intestinal barrier function, and decreased exposure of the colonic epithelium to carcinogens. Conclusions: Current evidence supports a protective role of dietary fiber in colorectal cancer prevention, although the magnitude of this effect may depend on fiber type, dietary patterns, and gut microbiota composition. Increasing dietary fiber intake may represent an effective strategy for reducing colorectal cancer risk. Further studies integrating microbiome and metabolomic approaches are needed to clarify causal mechanisms.