Inclusion Criteria:  Age 18 to 80 years old; any gender; Chronic pancreatitis etiology: idiopathic, biliary dependent, drug-induced, alcoholic, dysmetabolic, CP as a consequence of recurrent and severe acute pancreatitis (postnecrotic); History of confirming diagnostic criteria of CP (in accordance with 1) Clinical guidelines of the Russian Gastroenterological Association on the diagnosis and treatment of exocrine pancreatic insufficiency 2018; 2) Clinical guidelines of the unified European guidelines for gastroenterology, on the diagnosis and therapy of chronic pancreatitis 2017; 3) Clinical guidelines of the American College of Gastroenterology 2020); CP diagnosis according to multispiral computed tomography of the abdominal cavity and/or endoscopic ultrasonography of pancreas: size changes; dilatation of the main pancreatic duct more than 2 mm; increased echogenicity of the walls, uneven contours and heterogeneity of the BP parenchyma, concrements or calcification of the parenchyma; Clinical manifestations of exocrine insufficiency of pancreas: stool disorders (mushy/liquid stool, number of defecation acts >3 p/day, undigested food remains), steatorrhea, abdominal distention, nausea/vomiting, weight loss progression with adequate caloric intake and no other objective reasons of weight loss; Fecal elastase-1 values less than 200 µg/g (for CP groups with EPI) or more than 200 µg/g (for CP group without concomitant EPI); Informed patient consent to participate in the study.  Exclusion Criteria:  Acute pancreatitis; Hepatitis, cirrhosis of any etiology; Any acid-dependent diseases requiring immediate or long-term proton pump inhibitor therapy (PPI): gastroesophageal reflux disease, acute gastroduodenal erosions of any etiology; Zollinger-Ellison syndrome, etc; Stenosis of pylorys or duodenum; Condition after gastric resection or gastrectomy; Obstructive and autoimmune CP; Mesenteric ischemia syndrome; Any other cause of chronic diarrhea (irritable bowel syndrome with diarrhea predominance, gluten enteropathy, lactase deficiency, inflammatory bowel disease, etc.); Concomitant administration of drugs directly affecting exocrine pancreatic secretion (octreotide); Any concomitant diseases in the stage of decompensation (cardiovascular, renal failure, diabetes mellitus, etc.); Chronic infectious diseases requiring constant (long-term) supportive therapy, including HIV infection, etc; Hypersensitivity to pancreatin; Use of pro-, pre-, synbiotics, week prior to inclusion in this study; Use of antibiotics within 4 weeks prior to inclusion in this study; Pregnancy and lactation; Use of prohibited concomitant therapy during the study: pro-, pre-, synbiotics, including dietary fiber preparations and lactulose, as well as antibiotics, intestinal antiseptics, loperamide, intestinal sorbents.