Evaluate the effects of Suyusu (immunonutrition) in postoperative adjuvant chemotherapy for gastrointestinal cancer patients. The main endpoint of the study was the incidence of chemotherapy related adverse reactions (including bone marrow suppression, nausea and vomiting, diarrhea, and mucositis) in patients after two cycles of chemotherapy. The secondary endpoint indicators were: quality of life score (EORTC-QLQ-C30), nutritional risk score (PG-SGA, NRS2002), nutritional assessment indicators, changes in immune microenvironment, analysis of psychological status, survival time (1-year progression free survival rate), treatment tolerance (dose intensity, rate of treatment interruption, delay), etc.

Inclusion Criteria:

1. Subjects voluntarily and sign an informed consent form;
2. Age ≥ 18 years old and ≤ 75 years old;
3. Patients with stage II-III gastrointestinal malignancies with clear pathological diagnosis and undergoing radical surgery
4. No adjuvant chemotherapy received after surgery
5. The Eastern Cancer Collaborative Group's Physical State Score (ECOG) is 0-2 points;
6. No contraindications to chemotherapy and the use of fluorouracil based chemotherapy regimens;

Exclusion Criteria:

1. Allergy to the components of immune nutrients, allergic constitution, or other inability to eat;
2. Participated in other drug or food clinical trials within 2 months prior to enrollment;
3. Having a history of immune deficiency, including HIV testing positive, or having other acquired or congenital immune deficiency diseases, or having a history of organ transplantation, or active infections that are not suitable for chemotherapy (as determined by the researcher);
4. Subjects cannot guarantee compliance after participating in the study;
5. Other researchers believe that it is not suitable for enrollment.