Total available carbohydrate (sugars and starches) and total dietary fiber (soluble and insoluble) make up the total carbohydrate content of a food. Soluble fiber decreases the availability of glucose by delaying its absorption in the proximal small intestine, thus reducing the postprandial glucose levels (Jenkins et al., 1978; Schneeman, 1987a). Carrageenan, a seaweed extract, is a good source of soluble fiber (Montaño et al., 1985). This study aimed to determine the effect of carrageenan incorporation into arroz caldo on carbohydrate availability by monitoring the postprandial blood glucose levels of normal subjects. Control and experimental arroz caldo samples were prepared and subjected to proximate analysis and feeding studies. The total dietary fiber (TDF) content of the experimental (2.03%) was about thrice that of the control (0.68%). Using randomized crossover design, preweighed 55 g available carbohydrate serving portions of control and experimental arroz caldo samples, with 3.45 and 14.84 g TDF, respectively, were fed to ten fasting normal subjects then their postprandial blood glucose levels were determined at 15, 30, 45, 60 and 90 min intervals. Results of the short-term in vivo study showed that the mean postprandial glycaemic responses of subjects after consuming the experimental sample were significantly lower than the levels after consuming the control at 15, 45, and 90 min (P < or = 0.05) and at 30 min (P < or = 0.001). Likewise, the mean glucose area under the curve was significantly lower (P < or = 0.01) after consumption of experimental (69.22 +/- 32.94) arroz caldo than control (147.29 +/- 53.34). The hypoglycaemic effect of carrageenan may prove useful in the prevention and management of metabolic conditions such as diabetes.