Impact of Dietary Fiber as Prebiotics on Chemotherapy-related Diarrhea in Patients With Gastrointestinal Tumors

Inclusion Criteria: * Age 18-65, be able to comply with the protocol * Life expectancy greater than 3 months * Patients with cytologically or histologically confirmed diagnosis of gastrointestinal cancers * Undergoing chemotherapy, not synchronized with radiotherapy and other anti-tumor treatments * Chemotherapy-related diarrhea grade 2-4 * Not experience diarrhea before chemotherapy Exclusion Criteria: * age\<18 or \>65 * Patients who cannot eat by mouth for example chewing disorders, difficulty swallowing, intractable vomiting, gastrointestinal obstruction or gastrointestinal tract bleeding * Other acute or chronic diarrhea or colostomy * Patients with other severe adverse effects of chemotherapy other than diarrhea * Patients with severe diseases of heart, kidney, liver and other major organs * Use of any other drug for promoting intestine movement * Use of any other drug or dietary supplement for chemotherapy-related diarrhea such as other fiber supplements, probiotics, octreotide * Allergic to the components of the intervention dietary supplements; * Pregnancy (positive serum pregnancy test) and lactation * Any other serious or uncontrolled illness which the investigator think is undesirable for the patient to enter the trial