Dietary fiber intake and risk of colorectal cancer and incident and recurrent adenoma in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial

Abstract

Background: Dietary fiber has been associated with a reduced risk of colorectal cancer. However, it remains unclear at which stage in the carcinogenic pathway fiber may act or which food sources of dietary fiber may be most beneficial against colorectal cancer development. Objective: The objective was to prospectively evaluate the association between dietary fiber intake and the risk of incident and recurrent colorectal adenoma and incident colorectal cancer. Design: Study participants were identified from the intervention arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Participants received flexible sigmoidoscopy at baseline and 3 or 5 y after. Dietary fiber intake was measured by using a self-reported dietary questionnaire. The colorectal cancer, incident adenoma, and recurrent adenoma analyses were based on 57,774, 16,980, and 1667 participants, respectively. Unconditional logistic regression was used to assess the risk of incident and recurrent adenoma, and Cox proportional hazards models were used to assess the risk of colorectal cancer across categories of dietary fiber intake, with adjustment for potential confounders. Results: Elevated total dietary fiber intake was associated with a significantly reduced risk of incident distal colorectal adenoma (OR highest vs. lowest tertile of intake : 0.76; 95% CI: 0.63, 0.91; P-trend = 0.003) but not recurrent adenoma (P-trend = 0.67). Although the association was not statistically significant for colorectal cancer overall (HR: 0.85; 95% CI: 0.70, 1.03; P-trend = 0.10), a reduced risk of distal colon cancer was observed with increased total fiber intake (HR: 0.62; 95% CI: 0.41, 0.94; P-trend = 0.03). Protective associations were most notable for fiber originating from cereals or fruit. Conclusions: This large, prospective study within a population-based screening trial suggests that individuals consuming the highest intakes of dietary fiber have reduced risks of incident colorectal adenoma and distal colon cancer and that this effect of dietary fiber, particularly from cereals and fruit, may begin early in colorectal carcinogenesis. This trial was registered at clinicaltrials.gov as NCT01696981.Am J Clin Nutr 2015;102:881-90.

Inverse associations of dietary fiber and menopausal hormone therapy with colorectal cancer risk in the Multiethnic Cohort Study

“…We also found no evidence for differences in the fiber‐colorectal cancer association among the five racial/ethnic groups of the MEC in both men and women. The current findings support the conclusion on dietary fiber and colorectal cancer from the CUP of the WCRF/AICR, along with that of other more recent prospective studies, including the updated analysis confirming the previous findings from the European Prospective Investigation into Cancer and Nutrition …”

A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males

“…may have been due partially to their fiber intake. It is known that higher fiber intakes are associated with a lower risk of cardiovascular disease, cancer, and all-cause mortality [14–16]. On the other hand, the cholesterol intake of our subjects was twice as high as the typical recommendation of 300 mg per day [17].…”

Dietary and Lifestyle Factors Associated with Colorectal Cancer Risk and Interactions with Microbiota: Fiber, Red or Processed Meat and Alcoholic Drinks

“…Though the results of these studies are inconsistent, a meta-analysis stated an approximately 10% lower risk of colorectal adenoma (CRA) per 10 g/day increase in fiber [11] . Recently, a large prospective study within a population-based screening trial pointed out that elevated total dietary fiber intake have reduced risks of incident CRA and distal colon cancer, but not of recurrent adenoma and CRC overall [12] . Based on these results and the benefit for other systems such as cardiovascular disease [13] , a high-fiber diet can reasonably be recommended.…”