Dietary fiber or non-starch polysaccharides (NSP) may provide protection from CRC development. Epidemiologic studies on the association between dietary fiber and CRC is inconsistent are limited on NSP as a modifiable risk factor. Using the Singapore Chinese Health Study, a population-based prospective cohort of 61,321 cancer-free middle-aged or older Chinese Singaporeans, we examined the association between dietary fiber and NSP intakes and CRC risk. Fiber and NSP intakes at baseline were obtained using a validated semi-quantitative food frequency questionnaire coupled with the Singapore Food Composition Database. Cox proportional hazard regression model was used to estimate the hazard ratios (HRs) and respective 95% confidence intervals (CIs) for CRC associated with dietary fiber and NSP intakes after adjusting for potential confounders. After an average of 17.5 years of follow-up, 2,140 participants developed CRC. NSP was inversely associated with the risk of CRC in a dose-dependent manner whereas dietary fiber was not associated with risk of CRC overall or histologic subtypes. The multivariable-adjusted HRs (95% CIs) of CRC for quartiles 2, 3 and 4 of dietary NSP intake were 0.99 (0.88-1.11), 0.98 (0.87-1.11) and 0.84 (0.73-0.95), respectively, compared with the lowest quartile (P trend =0.006). This inverse association was more apparent for colon cancer (HRQ4 vs. Q1=0.79, 95% CI: 0.67-0.93, P trend =0.003) than rectal cancer (HR Q4 vs. Q1=0.92, 95% CI: 0.74-1.13, P trend =0.53). Our findings suggested that dietary NSP but not fiber is associated with a reduced risk of colon cancer in Chinese Singaporeans.
Significance: Non-starch polysaccharides may be beneficial for colorectal cancer primary prevention.
Keywords: Dietary Fiber; Non-starch Polysaccharide; colorectal cancer risk.