Anticancer potential of dietary fiber for colorectal carcinoma: a narrative review

Dietary fiber has emerged as a preventive and adjuvant therapy for patients with colorectal carcinoma (CRC) because it possesses chemoprotective and direct anticancer properties, including the ability to modulate multiple cellular and molecular targets implicated in tumor cell survival, proliferation, invasion, angiogenesis, and immunomodulation. This review summarizes the latest epidemiological, preclinical, and clinical research on dietary fiber as a preventive and adjuvant therapy for CRC patients, focusing on the cellular and molecular mechanisms of the bioactive compounds present in or produced by fiber metabolism.

A structured literature search was conducted in PubMed using a Boolean search strategy to identify relevant studies on the association between dietary fiber and CRC. Studies unrelated to dietary fiber or CRC, non-peer-reviewed materials, and articles with insufficient methodological details were excluded to maintain the focus and quality of the review.

An overall body of epidemiological evidence suggests that the consumption of foods rich in dietary fiber or whole grains is associated with a reduced risk of CRC. Preclinical studies conducted in vitro and in animal models strongly support the hypothesis that dietary fiber is effective in preventing and treating CRC and provide mechanistic insights, indicating that diverse types of fiber, such as β-glucan, resistant starch, pectin, and arabinoxylan, have distinct but complementary effects. However, the findings of the clinical trials are inconclusive. This disconnect may stem from the differences in methodologies, fiber types, dosages, intervention durations, and endpoints across studies.

According to the current evidence, dietary fiber appears to have a protective effect against the development of CRC. However, more targeted and prospectively planned RCTs using standardized dosages, formulations and combinations of dietary fiber are needed to provide additional evidence in favor of the recommendation of a high-fiber diet for the prevention and adjuvant treatment of CRC.