Cephalic phase responses to sweet taste

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Abstract
The sweet taste of nonnutritive sweeteners has been reported to increase hunger and food intake through the mechanism of cephalic-phase insulin release (CPIR). We investigated the effect of oral sensation of sweetness on CPIR and other indexes associated with glucose metabolism using nutritive and nonnutritive sweetened tablets as stimuli. At lunchtime, 12 normal-weight men sucked for 5 min a sucrose, an aspartame-polydextrose, or an unsweetened polydextrose tablet (3 g) with no added flavor. The three stimuli were administered in a counterbalanced order, each on a separate day at 1-wk intervals. Blood was drawn continuously for 45 min before and 25 min after the beginning of sucking and samples were collected at 1-min intervals. Spontaneous oscillations in glucose, insulin, and glucagon concentrations were assessed as were increments (slopes) of fatty acid concentrations during the baseline period. The nature of the baseline (oscillations: glucose, insulin, and glucagon; and slopes: fatty acids) was taken into account in the analyses of postexposure events. No CPIR and no significant effect on plasma glucagon or fatty acid concentrations were observed after the three stimuli. However, there was a significant decrease in plasma glucose and insulin after all three stimuli. Only the consumption of the sucrose tablet was followed by a postabsorptive increase in plasma glucose and insulin concentrations starting 17 and 19 min, respectively, after the beginning of sucking. In conclusion, this study suggested that oral stimulation provided by sweet nonflavored tablets is not sufficient for inducing CPIR.