*4.3.1 Drinking habits of alcohol and/or beer and risk of colorectal cancer*

Alcoholic beverages have been proven to be a major part of human's diet [53]. Excluding the poisonous effect of heavy intake of alcohol, we considered alcoholic beverages as a promoter of cancer in human. Most carcinogenic chemicals have a higher solubility in alcohol than in water. For example, aflatoxin B is soluble in ethanol but has a limited water solubility [54].

There is sufficient evidence for the carcinogenicity of alcohol beverages in human but inadequate evidence for the carcinogenicity of ethanol and alcoholic beverages in experimental animals [55]. Based on these facts and figures, we hypothesized that alcoholic beverages are promoters for cancer in humans. In this study, three levels of alcoholic drinking were categorized, including not drinking, some drinking per week, and daily drinking. Those who daily consume alcoholic beverages were at a significantly higher risk of colorectal cancer, with OR = 1.91, 95% CI = 0.98–3.72, and *p* for trend <0.05 (**Table 9**) [50].
