Inflammatory Bowel Disease (IBD) is a group of conditions which includes the autoimmune diseases ulcerative colitis and Crohn’s disease. The understanding of IBD has increased and thanks to research it’s now known that the potential causes of these diseases are many and can vary between different patients. Factors that researchers have been able to identify are diet, stress, cesarean birth, antibiotic use, nutritional deficiencies and other aspects of our modern lifestyle. Above all, however, deviations have been found in several different factors that affect the function of the intestine and the composition of the intestinal flora in these patients. Examples are bacterial and fungal infections, SIBO, imbalances between different groups of gut bacteria, and reduced amounts of important fatty acids produced by beneficial bacteria. Because the underlying causes of IBD vary between individuals, treatment needs to be individually tailored.