Effect of edible seaweeds (Undaria pinnatifida and Porphyra ternera) on the metabolic activities of intestinal microflora in rats

Abstract

A fiber-free diet supplemented with cellulose, Nori, or Wakame as the principal source of dietary fiber was fed to rats for 12 days, and the cecal bacterial activities (β-glucuronidase, β-glucosidase, azoreductase, nitroreductase and nitrate reductase) were measured. The intake of seaweeds did not affect body weight gain nor food intake; however, algae in the diet was associated with a significant increase on cecal, fresh stool and dry stool weight. All bacterial enzyme activities were lower in the two seaweed groups than the cellulose fed group with exception the of β-glucosidase which was significantly lower in rats fed Wakame. Adaptation to diets containing Nori or Wakame was associated with changes in microbial activity that involved a decrease on reductive and hydrolytic enzymatic activities implicated in the conversion of procarcinogens into carcinogens. The combination of the effect on the gut flora and a more rapid transit of feces would be expected to reduce exposure to potential carcinogens and may have health implications for human nutrition.