Colonization efficiency and immune stimulation after human microbiota inoculation in mice is known to be poor compared to mouse microbiota inoculation. We tested the colonization efficiency and immune responses in mice bred for one additional generation after inoculating the parent generation with either a human or a mouse microbiota. The mice were fed either a diet, in which the proportion of macronutrients resembled that of human or a diet, in which the nutrient sources were more comparable to animal diet . Although significantly lower in mice with a human microbiota (30-40 % versus 61-70 %) the colonization efficiency was significantly higher in human microbiota mice fed the human profile diet (40 %), and in mouse microbiota mice fed the animal source diet (70 %). The microbiota of mice fed the human profile diet was comparable to the microbiota of mice fed a standard rodent chow, while the microbiota of mice fed the animal source diet clustered separately. Mice inoculated with mouse fecal matter had significantly more CD4+ T cells and Cd4 expression and significantly fewer regulatory T cells and FoxP3 expression than human microbiota inoculated mice, but cell count differences were mostly apparent between mice fed the animal source diet. Mice fed the human profile diet had significantly higher expression of Cd8a. It is concluded that in mice a diet with a human profile may support the establishment of a human microbiota, which will, however still elicit a lower colonization efficiency compared to mice inoculated with a mouse microbiota.