Wheat bran has been consistently reported to protect against colon cancer. To investigate the mechanism of the unique characteristics of wheat bran, the morphology and zeta potential of micro-particles released from wheat bran and sugarcane bagasse fermentation by human faecal flora were studied by atomic force microscopy and laser light scattering technique, respectively. Microparticles released from wheat bran fermentation differed significantly from those produced from sugarcane bagasse fermentation in shape, size (237 VS 454 nm), and zeta potential (-20.01 VS -3.96 mv). Scanning electron microscopic observations showed that the structure of fermented residue of wheat bran was more loose and porous than that of sugarcane bagasse, and had a larger surface area. In vitro studies revealed higher binding capacities of fermented wheat bran for bile acid, cholesterol, and peanut oil compared with fermented sugarcane bagasse.