All experimental studies in cancer are eventually aimed at limiting or curing the disease. When relationships have been established between environmental factors and the incidence of a particular disease, whether benign or malignant, evasive action can be taken before the actual causative agents or mode of action is understood. Cholera was evaded by the avoidance of sewage-contaminated water a century before the v. cholera was identified as the cause of the disease. Lung cancer can largely be avoided by abstinence from smoking cigarettes, although the carcinogenic mechanism whereby tobacco smoke causes cancer is not yet understood. A relationship can be demonstrated between certain bowel diseases and diet, and although this has not yet been shown to be causitive in the case of cancer, the relationship between an over-refined diet and diverticular disease can now be considered established. In view of the evidence, it seems justifiable to issue a warning against the removal of so much of the unabsorbable fiber from our food, and the associated over-ingestion of refined carbohydrates.