Folic acid and B12 are critical to DNA synthesis and repair; and alterations in DNA synthesis and repair is a hallmark of cancer. Chronic use of alcohol is known to decrease folic acid and B12, and increase the risk of cancer, throughout the gastrointestinal tract. Immortal pathogens (chlamydia, H-pylori, and intestinal parasites) decrease levels of folic acid and B12 in tissue, and also increase the risk of cancer. The combination of chronic alcohol use and chronic infection with immortal pathogens accelerates loss of folic acid and B12, which further increases the risk of cancer.