MedicalResearch.com Interview with: Michael J. Orlich, MD, PhD Program Director, Preventive Medicine Residency Loma Linda University Co-Investigator, Adventist Health Studies Medical Research: What is the background for this study? What are the main findings? Dr. Orlich: Colorectal cancer is the second leading cause of death from cancer in the United States.  Screening efforts such as colonoscopies have helped save many lives by detecting pre-cancerous polyps and removing them.  However, it is even better to prevent cancers from forming in the first place.  We call this primary prevention.  Diet is a potentially important approach to reduce the risk of developing colorectal cancer.  In this analysis, we compared those eating different categories of vegetarian dietary patterns to those eating a non-vegetarian diet.  About half of our study population was classified as non-vegetarian, which we defined as eating meat at least weekly.  The other half of our population we called vegetarian and further divided them into four different vegetarian groups:  semi-vegetarians ate meat but less than once per week; pesco-vegetarians ate fish but avoided other meats; lacto-ovo-vegetarians avoided meat but ate eggs and/or dairy products; and vegans avoided all meats, eggs, and dairy.  All vegetarians together had on average a 22% relative reduction in the risk of developing colorectal cancer, compared to non-vegetarians, after carefully adjusting for many other factors.  Pesco-vegetarians in particular had a much lower risk compared to non-vegetarians. (more…)