Carbohydrates, glycemic index, glycemic load, and colorectal cancer risk: a systematic review and meta-analysis of cohort studies
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Dietary carbohydrate, glycemic index, and glycemic load are thought to influence colorectal cancer risk through hyperinsulinemia. We review and quantitatively summarize in a meta-analysis the evidence from prospective cohort studies.
We searched the PubMed database for prospective studies of carbohydrate, glycemic index, and glycemic load and colorectal cancer risk, up to October 2011. Summary relative risks were estimated by the use of a random effects model.
We identified 14 cohort studies that could be included in the meta-analysis of carbohydrate, glycemic index, and glycemic load and colorectal cancer risk. The summary RR for high versus low intake was 1.00 (95% CI: 0.87–1.14, I 2 = 31%) for carbohydrate, 1.07 (95% CI: 0.99–1.16, I 2 = 28%) for glycemic index, and 1.00 (95% CI: 0.91–1.10, I 2 = 39%) for glycemic load. In the dose–response analysis, the summary RR was 0.95 (95% CI: 0.84–1.07, I 2 = 58%) per 100 grams of carbohydrate per day, 1.07 (95% CI: 0.99–1.15, I 2 = 39%) per 10 glycemic index units, and 1.01 (95% CI: 0.95–1.08, I 2 = 47%) per 50 glycemic load units. Exclusion of one or two outlying studies reduced the heterogeneity, but the results were similar.
This meta-analysis of cohort studies does not support an independent association between diets high in carbohydrate, glycemic index, or glycemic load and colorectal cancer risk.
KeywordsCarbohydrate Glycemic index Glycemic load Colorectal cancer Meta-analysis
We thank the systematic literature review team at the Wageningen University for their contributions to the colorectal cancer database. This work was funded by the World Cancer Research Fund (grant number 2007/SP01) as part of the Continuous Update Project. The views expressed in this review are the opinions of the authors. They may not represent the views of WCRF International/AICR and may differ from those in future updates of the evidence related to food, nutrition, physical activity, and cancer risk. All authors had full access to all of the data in the study. D. Aune takes responsibility for the integrity of the data and the accuracy of the data analysis. The authors declare that there are no conflicts of interest.
Conflict of interest
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