Inflammatory bowel diseases are chronic inflammatory disorders of the gastrointestinal tract of unknown cause. Inflammatory bowel disease (UBC) includes Crohn's disease (CB), ulcerative colitis (UC) and undetimeric colitis. Ulcerative colitis is an inflammatory bowel disease that is limited to the lining of the colon, mainly affecting the rectum but can spread to other parts. Unlike UC, CB can affect any part of the digestive tract, so the involvement can be different in different places, so the symptoms are different. For people with UBC, diet plays an important role. A certain type of diet can increase the risk of developing UBC but also reduce the risk of developing them. Clinical nutrition and diet therapy are very important components in the treatment of patients with UBC. Improving nutritional status leads to a better outcome for patients with UBC so communication by a multidisciplinary team is important. The aim of this final paper is to point out the increase in the number of patients with inflammatory bowel disease, the importance of proper nutrition both before the diagnosis itself for the purpose of prevention and after the diagnosis. Also, the goal is to show the number of people suffering from UBC in the area of northern Croatia, to compare the obtained results with the research conducted for eastern Croatia and to analyze them. Then, to see the eating habits of the patients before and after the diagnosis, the way in which and whether the diet has changed, and to examine which foods are most difficult for the participants to tolerate. Respondents from northern Croatia see that they have improved their eating habits in the form of consuming a larger number of smaller meals, consuming probiotics and prebiotics as well as supplements in relation to before they fell ill, but the understanding of eating habits in the context of avoiding unwanted foods is missing.