Inhibitory effects of laminaran and low molecular alginate against the putrefactive compounds produced by intestinal microflora in vitro and in rats

The inhibitory effects of laminaran and low molecular weight sodium alginate (MW = 49,000) against formation of ammonia, indole compounds and phenol compounds, putrefactive and harmful compounds, induced by human fecal microflora, were examined in vitro. Laminaran was fermented to acetate, propionate, n-butyrate and lactate. The alginate was fermented to acetate and propionate. Both of these polysaccharides inhibited formation of the putrefactive compounds. In the case of rats fed diet containing 2% (w/w) laminaran or low molecular alginate, the fermentation pattern agreed with that of the in vitro experiment. Laminaran suppressed indole, p-cresole and sulfide, significantly. These putrefactive compounds, in rats fed low molecular alginate, also tended to be lower. These results suggest that the fermentation of laminaran by intestinal bacteria suppresses the putative risk markers for colon cancer. (C) 2004 Elsevier Ltd. All rights reserved.