Inhibitory Effect of Calcium Alginate on Postprandial Blood Glucose Elevation: Basic and Clinical Studies

Diabetes is known to increase the risk of myocardial and cerebral infarction, as well as complications such as retinopathy, nephropathy and neuropathy. It is important for diabetics to improve their eating habits, for example, by eating slowly, avoiding overeating, and increasing their intake of vegetables, in order to suppress sudden rises in blood glucose (Glu) levels. On the other hand, alginic acid (Alg), which is a polysaccharide derived from brown algae, is used as a food and medicinal additive, a health food and a pharmaceutical, based on its blood cholesterol-lowering effect and protective effect on the gastric mucosa. It was recently reported that calcium alginate (Ca-Alg) has the pharmacological effect of suppressing blood Glu elevation. We investigated the mechanism of this effect and found that Ca-Alg inhibits the metabolism of starch in the gastrointestinal tract by inhibiting the activity of α-glucosidase, which degrades maltose into Glu.We also examined the influence of the amount of Ca-Alg added to the diet and the particle size of the Ca-Alg on postprandial blood Glu elevation in rats. Subsequently, we conducted several clinical trials. We asked healthy adults to eat udon noodles, soba (buckwheat noodles), and Chinese noodles containing CaAlg, and measured the blood Glu levels after consumption. In each case, Ca-Alg decreased blood Glu levels and suppressed total absorption of Glu. This review summarizes the results of our basic and clinical studies on the effects of Ca-Alg on postprandial blood Glu elevation.