Statement of Purpose: Vitamin C (ascorbic acid) and vitamin B3 (niacin) have been extensively studied since the 20th century. In the area of stem cell biology, vitamin C has shown its direct impact towards homeostasis and epigenetics changes1. Vitamin B3 has shown abilities in maintaining healthy intestinal hemostasis and reducing gut inflammation by participating in the rapamycin signaling pathway2. In this study, high doses of vitamin C and vitamin B3 (600 and 1200 μg/ml) were used to study their effects on four different types of primary intestinal organoids. These organoids were isolated from a C3H/HeN defined-flora mouse (C3H ASF), a C3H/HeN Conventional Raised mouse (CONV_R), a 129S definedflora mouse (129 ASF), and a 129S defined-flora IL-10 deficient (IL-10) mouse. The CONV_R and ASF mice came from the same strain; however, both ASF mice only have eight specific bacterial species inside its gastrointestinal (GI) tract, which are two Lactobacilli, one Bacteroides, one bacterium of the Flexistipes genus, and four Fusobacterium species. ASF and IL-10 mice both have the same types of bacterial species; however, the strain and genetic background of these mice are different. For IL-10 and CONV_R mice, their strains, genetic background, and microbiota environments are different. Because of these differences among the four types of mice, this study provides us a primary understanding of how vitamins influenced intestinal health within different GI environments, which offer potential opportunities to use C and B12 as new materials to modulate and improve GI health.