Scope: To investigate the effects of postoperative parenteral nutrition (PN) with multivitamins supplementation on oxidative stress and metabolism. Methods and results: The participants are randomly assigned in a 1:1 ratio to groups: total nutrient admixture (TNA) + multivitamin (n=14, Group A) and TNA + normal saline (n=16, Group B). The levels of blood vitamins, ILs, and MDA are assessed and the dysregulation of metabolism is analyzed using nontargeted metabolite profiling. The degree of postoperative stress in Group A is significantly lower than that in Group B by analyzing changes in the levels of IL-8 and MDA. A set of 43 features are qualified to have a variable importance parameter score of >1.5 of a partial least-squares discriminate analysis model and fold change of >1.5 at p-value <0.05 between Groups A and B. The principal metabolic alternations in Group A include increased tricarboxylic acid cycle and ketogenesis with reduced plasma-free amino acids. Backing the results of clinical biomarkers, increased levels of antioxidative molecules, together with decreased levels of inflammatory related polyunsaturated fatty acids, are observed. Conclusion: Postoperative PN enhanced by multivitamins can alleviate traumatic stress and improve metabolic transition from catabolism to anabolism in gastric cancer patients.