<p>The influence of soymilk on the fecal microbiota, particularly Bifidobacterium species, and metabolic activities were investigated in eight healthy adult humans. During the soymilk intake period, the number of bifidobacteria in feces was significantly higher (p<0.05) on day 14 of the soymilk intake period than before the intake period, whereas that of Enterobacteriaceae was significantly lower (p<0.05) on days 7 and 14 of the soymilk intake period than before the intake period. In an investigation of Bifidobacterium at the species or group level, the numbers of all species and groups studied slightly increased during the soymilk intake period. These results show that the intake of soymilk may contribute to improving the intestinal environment.</p>