Jan Chojnacki is a professor and head of the Department of Clinical Nutrition and Gastroenterological Diagnostics, Medical University of Lodz, Lodz, Poland. He received his doctoral degree/habilitated doctor/professor at the Department of Gastroenterology, Military Medical Academy, Lodz from 1974 to 1990. His research interests are melatonin, medicine, irritable bowel syndrome, Helicobacter pylori, and internal medicine. He is also a member of the Polish Society of Gastroenterology and the Rector of the Military Medical Academy (Military Medical Academy).