This much is known:   -- Excessive alcohol consumption contributes to colon cancer in everyone.-- The more risk factors you have, the more likely you are to develop colon cancer.-- Both Crohn's and alcohol consumption are risk factors for developing colon cancer.     Most sources recommend that Crohn's patients limit the amount of alcohol they drink. In fact, many advise no alcohol at all, because it can irritate the intestines and precipitate a Crohn's flare, or assist in triggering a flare. Also, alcohol can worsen diarrhea, so it should be avoided. Alcohol is also a depressant, and people with Crohn's are often stressed and depressed enough by their symptoms, and the social ramifications of their disease, without the addtion of a chemical depressant.   The American Cancer Society (ACS) reports that one reason why heavy drinkers are at high risk for colon cancer, is they tend to have lower levels of folic acid--already a problem for many Crohn's patients. The ACS advises that men have no more than two drinks a day, and women have no more than one.