Dietary intake of polyphenols and risk of colorectal cancer and adenoma-A case-control study from Iran

Objectives: The aim of this study is to examine the relationship between dietary polyphenols' classes and individual polyphenol subclasses and also the risk of Colorectal cancer (CRC) and colorectal adenomas (CRA).

Design: A hospital-based case-control study on the association between CRC and CRA and dietary polyphenols was conducted.

Setting: Overall, 129 colorectal cancers, 130 colorectal adenoma cases and 240 healthy controls were studied in three major general hospitals in Tehran province, Iran.

Results: In a multivariate-adjusted model for potential confounders, higher consumption of stilbenes (OR 0.49 for the highest vs. the lowest quartile; 95% CI = 0.24-0.99; p for trend = 0.013) was associated with the decreased risk of CRA. Moreover, an inverse association between the risk of CRC and the intake of total polyphenols (OR 0.05 for the highest vs. the lowest quartile; 95% CI = 0.01-0.19; p for trend=<0.001), total flavonoids (OR 0.36 for the highest vs. the lowest quartile; 95% CI = 0.16-0.79; p for trend = 0.005), total phenolic acids (OR 0.24 for the highest vs. the lowest quartile; 95% CI = 0.10-0.56; p for trend = 0.002), anthocyanin (OR 0.21 for the highest vs. the lowest quartile; 95% CI = 0.08-0.55; p for trend = 0.001) and flavanols (OR 0.38 for the highest vs. the lowest quartile; 95% CI = 0.17-0.85; p for trend = 0.001) was observed.

Conclusion: The present study showed that a higher intake of total polyphenols, total flavonoids, total phenolic acids anthocyanin and flavanols was related to the decreased risk of CRC. The higher consumption of stilbenes was also inversely associated with the risk of CRA.