Nori seaweed consumption modifies glycemic response in healthy volunteers

Seaweeds constitute sources of a great diversity in dietary fiber (DF). They contain a high proportion of soluble DF, which may be a barrier to starch digestion, and as a consequence seaweeds may modify glycemic response and may be beneficial in human health. The objective of this research was to evaluate the effect of Nori alga on postprandial glycemic response in healthy volunteers. This could offer a potential use of algae not only as a food but also as an ingredient rich in soluble dietary fiber. The effect of 3g Nori alga on the postprandial glycemic response to white bread was measured. Capillary blood samples were taken in the fasting state and then at 15, 30, 45, 60, 90, and 120 min. after each meal. Plasma glucose concentrations were analyzed and incremental areas under plasma glucose curves were calculated to determine the glycemic index (GI) of Nori + white bread with respect to white bread alone. Glycemic response to white bread was used as reference. In vitro kinetics of starch digestion were determined to estimate GI. In vitro and in vivo results were compared. Nori alga slowed down the degree of in vitro starch hydrolysis. Nori taken along with bread decreased the sharp glucose peacks found for bread at 30-60 min, after its ingestion, glucose levels until 120 min. were moderate. The intake of Nori alga decreased the glycemic response to white bread in healthy volunteers, from 100 to 68%. In vitro kinetic results provided an idea of in vivo behavior therefore preliminary in vitro assays are recommended before initiating in vivo experiments. (C) 2000 Elsevier Science Inc.