Crohn's Disease is a form of intestinal bowel disease (IBD) which is thought to have genetic and environmental causes. Based on a published study in the World Journal of Gastroenterology dated June 21, 2014, a bacteria called Mycobacterium Avium plays a role in 30-50% of those with Crohn's. What role it plays is not specified, but it is suspected to be a triggering factor or possibly root cause. In another recent study published in the Journal of Rheumatology (October, 2013), a bacteria called Klebsiella is implicated in causing or worsening Crohn's. In this study the authors recommend a low-starch diet as a means of trying to lower the bacteria, and they point to the fact that starch consumption creates a favorable environment for Klebsiella. They then made some general dietary recommendations based upon this, and here they are (If you have IBD, discuss dietary changes with your Doctor):
Recommended Diet for Crohn's Disease and Ankylosing Spondylitis Patients
Decreased Intake of “High-Starch-Containing Foods”
Increased Intake of “None-Low-Starch-Containing Foods”
Related to this, Rush University did a study which showed better microbial diversity in those who followed a lower-starch diet called the Specific Carbohydrate Diet.