Natto mucilage containing poly-gamma-glutamic acid increases soluble calcium in the rat small intestine

We prepared natto (fermented soybeans) mucilage containing poly-gamma -glut amic acid (gamma -PGA) from commercial natto, The effect of natto mucilage on calcium (Ca) solubility in vitro and in vitro was investigated. Ca solub ility in vitro increased with an increase in the amount of natto mucilage, due to inhibition of the formation of an insoluble complex of Ca with phosp hate by natto mucilage. Rats mere fed with 5 g of soybean protein isolate, natto, mucilage-free nat to, or natto mucilage diet for 1.5 h, Small intestinal contents mere collec ted 2.5 h after ingestion. In the lower half of the small intestine, both t he amount and the percentage of soluble Ca of intestinal contents mere sign ificantly higher (P<0.001) in rats fed with natto mucilage diet than in tho se fed with the other diets. Natto mucilage also increased Ca solubility in vivo. These results suggested that <gamma>-PGA is responsible for the incr easing effect of natto mucilage on Ca solubility.