Antimetastatic and immunostimulatory properties of fermented brown rice

The antimetastatic effect of fermented brown rice by Aspergillus oryzae(FBRA), a processed food, was examined in an animal model of metastasis to the liver using mouse colon cancer cells. Mice fed a diet containing 10% FBRA were inoculated with colon 26-L5 cells via the portal vein on day 14. Liver metastasis on day 28 was significantly inhibited by the FBRA-containing diet without an increase in body weight. To investigate the immunostimulatory activity, the cellular functions of macrophages were examined. Intracellular glutathione levels were increased in peritoneal macrophages (PEMs) prepared from mice fed FBRA for 18 days. FBRA did not induce the production of interferon-γ (IFN-γ) by itself, though enhanced the ability of PEMs to produce IFN-γ, but not interleukin-12 or tumor necrosis factor-α, in response to lipopolysaccharide (LPS). These results indicated that oral administration of FBRA inhibited the metastasis of colon 26-L5 cells to the liver through a mechanism leading to a Th1-dominant immune state and activation of macrophages via anti-oxidative properties.