Effects of oral immunonutrition on histological changes of inflammatory infiltration of the tumor microenvironment among patients with a new diagnosis of gastric cancer

•Oral immunonutrition (OI) may be effective in modulating inflammatory infiltration of the tumor microenvironment (TME).•Patients receiving preoperatory OI before gastric cancer resection showed modifications of inflammatory cells in the TME, including T-lymphocyte cluster of differentiation (CD) 8+, CD83+, and CD68+ cells.•After OI administration, a significant correlation was documented between CD68+ and CD40+.•OI may modulate inflammatory pathways within the TME with potential implications on clinical outcomes, including response to anticancer treatments.