Inclusion Criteria:  Age: 18-75 years old; Sex: Male or female; Pathologically confirmed gastric adenocarcinoma or colorectal adenocarcinoma; Patients who had received standard chemotherapy containing platinum or irinotecan developed grade 1-3 (NCI-CTCAE, version4.0) diarrhea in the previous cycle and recovered to grade 0 after symptomatic treatment; Patients are planned to receive the same chemotherapy regimen and dose as the previous cycle; A baseline Eastern Cooperative Oncology Group (ECOG) performance status of 0-2; Adequate haematopoietic function of bone marrow: neutrophils≥1.5x109 / L, platelets≥75x109 / L; normal liver and kidney function: TBIL≤ 1 upper limit of normal (ULN); ALT and AST ≤2.5 ULN; creatinine≤1.5 ULN; Estimated life expectancy ≥ 3 months; Be willing and able to provide written informed consent for the trial.  Exclusion Criteria:  (Patient-Generated Subjective Global Assessment, PG-SGA)>9 or severe malnutrition (weight loss > 10% or serum albumin < 30 g/L or body mass index < 18.5 kg/m2); Patients with severe heart, lung and brain diseases; chronic hepatitis infection, liver cirrhosis, chronic nephritis, kidney dysfunction, etc; Patients with infection-related fever; Patients who are known to be allergic or intolerant to any of the ingredients used in the study; Patients with long-term chronic diarrhea, abdominal pain, constipation or other digestive tract diseases; patients with gastrointestinal symptoms before chemotherapy (≥grade 2 NCI-CTCAE, version 4.0); Synchronously receive other treatments that may cause diarrhea, such as radiotherapy; Patients who take drugs for microecological regulation of digestive tract such as Combined Bifidobacterium, ChangTai oral liquid, etc; Patients take traditional Chinese medicine or antibiotics; Unable to understand and sign the informed consent form; participants in other clinical trials.