Effect of High-Legume Diet on Colorectal Cancer Risk

This study, sponsored by the National Cancer Institute and Penn State University, will examine how a diet high in legumes (dried beans) influences risk factors for colon cancer and polyps. Many scientists believe that colon and rectal cancers develop from polyps (tumors of the lining of the large bowel). This study will test whether a high-legume diet can reduce levels of certain factors (blood insulin, blood glucose, and markers of inflammation such as C-reactive protein) that at elevated levels are known to increase the risk of colorectal polyps and colon cancer. Healthy men between 35 and 75 years of age may be eligible for this study, conducted at Penn State University in University Park, Pennsylvania. Candidates are screened with blood tests and measurements of height, weight, and blood pressure. All candidates must have had a colonoscopy within 2 years of entering the study. They may or may not have had adenomas and may or may not be insulin-resistant. Candidates must not have cancer, heart disease, kidney disease, diabetes, or other serious medical condition, and they must have no history of colorectal cancer, polyp removal, bowel surgery, polyposis syndrome, or inflammatory bowel disease. Participants undergo the following tests and procedures: * Caloric requirement testing: The subject's resting metabolic rate is measured while fasting and in the early morning at rest to determine daily calorie requirement before beginning the study diet. A special clear plastic hood is placed over the subject's head while his breathing is measured. He can communicate with the technician at all times during the 30-minute test. * Study diet: Subjects follow two required 4-week diets with a 3-week break in between, followed by an optional third 4-week diet. Subjects eat a healthy American diet for both of the required 4-week diet periods; about 1-1/2 cups of cooked legumes, such as pinto, baked, and navy beans are added to one of the two required diets. For the third (optio