CYP1A1 and colorectal cancer: In this study, we examined whether a greater habitual dietary intake of flavonoid subclasses (flavonols, flavones, flavanones, flavan-3-ols, anthocyanidins, and isoflavones) is associated with a lower risk of colorectal cancer and whether the associations with certain flavonoid subclasses are altered by variants in the CYP1A1 gene.