Zora Djuric and researchers at the University of Michigan Comprehensive Cancer Center are looking at adults ages 21 or older who have had colon polyps, colon cancer or a family history of colon cancer.

Participants will be randomly assigned to follow either the Mediterranean diet or the Healthy People 2010 diet for six months. A dietitian will work closely with each participant by telephone. Participants can choose foods they prefer from recommended food group lists.

The Mediterranean diet focuses on vegetables, whole grains, fruits, fish and olive oil with high-fat meats and processed foods limited. The Healthy People 2010 diet, the U.S. Department of Health and Human Services' plan for healthy eating, involves eating plenty of fruits and vegetables, whole grains and a moderate fat intake with limits on saturated fat.

Previous studies have linked the Mediterranean diet to reduced risk of heart disease, stroke and cancer. Some evidence suggests the Mediterranean diet causes changes in the colon that would prevent cancer.