13. Alcohol
Studies by the National Cancer Institute have shown a link between alcohol consumption and cancers of the head and neck, esophagus, liver, breast, and colon.
Alternatives – If you are not ready to quit entirely, keep your alcohol consumption in the low risk category – no more than 3 drinks in a sitting for women and 4 drinks in a sitting for men, with no more than 7 drinks total per week for women and 14 total per week for men.