The bioavailability of magnesium from Wakame (Undaria pinnatifida) and Hijiki (Hijikia fusiforme) and the effect of alginic acid on magnesium utilization of rats.

The bioavailability of magnesium from Wakame and Hijiki, and the effects of alginic acid on absorption of dietary magnesium were examined in five groups of rats fed either control, Wakame, Hijiki, AW (containing the same amount of alginate as in the Wakame) and AH (containing the same amount of alginate as in the Hijiki) diets, and animals fed a low magnesium diet (LMg) (twentieth amount of magnesium in the original mineral mixtures as the control). Food intake and body weight gain were decreased by adding sodium alginate to the diets. A large amount of calcium accumulated only in the kidneys of the rats fed the LMg diet. Serum magnesium concentration decreased only in the LMg group. The magnesium content in the defatted left femurs did not differ between the control and Wakame fed animals and also among the animals eating Wakame, Hijiki and AW diets. The breaking force of the right femurs did not differ among all the groups except the LMg group. The ratio of apparent magnesium absorption (%) of the control, LMg, Wakame, Hijiki, AW and AH groups was 82.2, 72.7, 66.9, 50.8, 69.3 and 54.2 in the first experimental period, and was 75.3, 52.1, 57.7, 46.9, 62.6 and 60.5 in the second experimental period, respectively. It was clear that the bioavailability of magnesium in the Wakame fed rats was higher than in those eating the Hijiki. Large amounts of sodium alginate lowered magnesium absorption from the diet.

A comparison of physical properties, oxalate-oxalic acid soluble substances, protein content, and in vitro protein digestibility of the blue-green alga Nostoc commune Vauch. from the Philippines and Japan.

The physical properties, amount of oxalate-oxalic acid soluble substances (OOSS), protein and in vitro protein digestibility of Nostoc commune from the Philippines and Japan were determined. The samples were the spherical type from the Philippines (PS), the dry field discoid type from the Philippines (PD), and the dry field discoid type from Japan (JD). The discoid types, PD and JD, regardless of origin showed higher settling volume in water (SV) and bulk density than PS. The OOSS values obtained for all samples were directly related to SV and bulk density. The WHC level was highest in PS. This desirable characteristic makes PS a technologically potential sample for large-scale food production applications in the future. Protein and in vitro protein digestibility varied significantly among all samples. In general, the algal samples examined possess desirable physical properties which are expected to be related to physiological functions.

Hypocholesterolemic effect of blue-green alga, ishikurage (Nostoc commune) in rats fed atherogenic diet.

Blue-green alga, Nostoc commune is rich in dietary fiber. To examine the hypocholesterolemic effect, the alga or the dietary fibers were given to the rats fed cholesterol diet. Serum cholesterol elevation was significantly depressed in those rats. Cholesterol increased in the liver of rats given the alga and the fiber. The content of fecal cholesterol and bile acid unchanged. Of the dietary fibers, oxalate-oxalic acid soluble substance (OOSS) found abundant in the alga was most effective in lowering cholesterol in the serum. It seems to depress the elevation of LDL-cholesterol. The mechanism of hypocholesterolemic effect by OOSS remains to be unclear. This study indicated that Nostoc commune is expected to be a new dietary fiber source of possible importance in human nutrition.

Chemical composition, in vitro protein digestibility and in vitro available iron of blue green alga, Nostoc commune.

Blue-green alga, Nostoc commune, contained moderate amounts of protein and iron. Its in vitro protein digestibility was 43.50%. The soluble and ionic iron from the alga was extractable to some extent at pH 1.5 but was not detectable at pH 8.0. The digestion by protease did not affect the iron detection. Heat processing at 100 and 120 degrees C failed to increase the digestibility and the content of available iron. The dietary fiber in the alga may be responsible for low protein digestion and low iron availability.