A Western-style diet induces benign and malignant neoplasms in the colon of normal C57Bl/6 mice

Decreased dietary intakes of calcium, vitamin D and folic acid have been su ggested as risk factors for human colon cancer. We previously fed a Western -style diet (WD) containing reduced calcium, vitamin D and increased fat co ntent to normal C57/B16 mice: hyperproliferation, hyperplasia and whole cry pt dysplasias developed in the colon following WD administration. Utilizing the same diet, we now also decreased the levels of several nutrients that are required for biochemical reactions involving methyl group inadequacy, i .e. folic acid, methionine, choline and vitamin B-12. Dietary levels of the se nutrients were reduced to nutrient-density levels approximating those co nsumed by large segments of human Western populations. This further modific ation of the WD resulted in adenoma and carcinoma development in normal mou se colon (P < 0.04 compared with AIN-76A diet). The results indicate, for t he first time, that a semi-purified rodent diet designed to mimic the human Western diet can induce colonic tumors in normal mice without carcinogen e xposure.