Dietary Nonstarch Polysaccharide Intake and Risk of Colorectal Cancer: Findings from the Singapore Chinese Health Study

Abstract

Dietary fiber or nonstarch polysaccharides (NSP) may provide protection from colorectal cancer development. Epidemiologic studies on the association between dietary fiber and colorectal cancer 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 colorectal cancer risk. Fiber and NSP intakes at baseline were obtained using a validated semiquantitative food frequency questionnaire coupled with the Singapore Food Composition Database. Cox proportional hazard regression model was used to estimate the HRs and respective 95% confidence intervals (CI) for colorectal cancer 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 colorectal cancer. NSP was inversely associated with the risk of colorectal cancer in a dose-dependent manner, whereas dietary fiber was not associated with risk of colorectal cancer overall or histologic subtypes. The multivariable-adjusted HRs (95% CIs) of colorectal cancer 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 (Ptrend = 0.006). This inverse association was more apparent for colon cancer (HRQ4 vs. Q1 = 0.79, 95% CI: 0.67–0.93, Ptrend = 0.003) than rectal cancer (HR Q4 vs. Q1 = 0.92, 95% CI: 0.74–1.13, Ptrend = 0.53). Our findings suggested that dietary NSP but not fiber is associated with a reduced risk of colon cancer in Chinese Singaporeans. Significance: NSPs may be beneficial for colorectal cancer primary prevention.