In human volunteers, we evaluated changes in gene expression profiles, immunological indices, and intestinal microbiota of blood cells in subjects consuming a S.reticulata extract. Thirty healthy Japanese males were split randomly into a group ingesting 240 mg/day of S.reticulata extract -containing tablets for 4 weeks and a control group ingesting placebo tablets. Ingestion of the S.reticulata extract improved T cell proliferation and other immunological indices, and changed intestinal microbiota, increasing Bifidobacterium and Lactobacillales and decreasing Clostridium bacteria. Expression levels of many immuno-relevant genes were altered. We have shown the S.reticulata extract to enhance human immune functions.