Dietary fiber intake reduces risk for colorectal adenoma: a meta-analysis.
OBJECTIVE
Reports on the association between dietary fiber intake and risk of colorectal adenoma (CRA), the precursor of colorectal cancer, have been inconsistent. We conducted a meta-analysis of case-control and cohort studies to analyze this association.


METHODS
We searched the MEDLINE and EMBASE databases to identify relevant studies published through July 2013. A random-effects model was used to estimate summary relative risks (SRRs) and 95% confidence intervals (CIs) for associations between fiber intake and CRA risk. Heterogeneity among studies was assessed using the Cochran Q and I(2) statistics.


RESULTS
Our meta-analysis included 20 studies involving 10,948 subjects with CRA. The SRRs of CRA for total dietary fiber were 0.72 (95% CI, 0.63-0.83) in a high- vs low-intake analysis and 0.91 (95% CI, 0.87-0.95) per 10-g/day increase in fiber intake in a dose-response model. Subgroup analyses indicated a significant inverse association between total fiber intake and CRA risk in case-control studies (SRR, 0.66; 95% CI, 0.56-0.77), but not in cohort studies (SRR, 0.92; 95% CI, 0.76-1.10). The SRRs of CRA were 0.84 for fruit fiber (95% CI, 0.76-0.94; n = 6 studies), 0.93 for vegetable fiber (95% CI, 0.84-1.04; n = 6 studies), and 0.76 for cereal fiber (95% CI, 0.62-0.92; n = 9 studies) in high- vs low-intake analyses.


CONCLUSIONS
Our findings support the hypothesis that high dietary fiber intake is associated inversely with CRA risk. Further studies with prospective designs that use validated questionnaires and control for important confounders are warranted.
Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, PR China.
Qiwen
Q
Ben
Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, PR China.
Yunwei
Y
Sun
Department of Colorectal Surgery, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang, PR China.
Rui
R
Chai
Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, PR China.
Aihua
A
Qian
Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, PR China.
Bin
B
Xu
Department of Gastroenterology, Ruijin Hospital, Shanghai Jiaotong University, Shanghai, PR China. Electronic address: yaozongyuan28@126.com.
Yaozong
Y
Yuan
D000236:Adenoma / Q000453:epidemiology* / Q000517:prevention & control*; D016022:Case-Control Studies; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000517:prevention & control*; D004043:Dietary Fiber / Q000627:therapeutic use*; D006801:Humans; D012307:Risk Factors
Colon Cancer; Food; Reduction; Risk Factor