The stomach's response to unappetizing food: cephalic-vagal effects on gastric myoelectric activity.

The aim of this investigation was to determine the effects of sham feeding food that was perceived as unappetizing on the cephalic-vagal reflex as measured by changes in gastric myoelectric activity. Thirty-eight healthy human participants experienced one of two conditions: (i) an appetizing sham feeding condition in which participants chewed and expectorated two cooked frankfurters, and (ii) an unappetizing sham-feeding condition in which participants chewed and expectorated two cold tofu frankfurters. All participants were asked to chew each mouth-full of food 6-7 times and to be very careful not to swallow any of the food. Electrogastrograms (EGGs) were recorded for 10 min prior to, during, and for 15 min after sham feeding. A questionnaire was given to each participant after the procedure as a manipulation check and to assess food palatability. Results from the questionnaire showed, as expected, that the cooked frankfurters were significantly more appetizing than the cold tofu frankfurters (P < 0.01). In the group sham fed appetizing food, 3 cycles per minute (cpm) power increased during sham feeding, but the change was not significant; however, 3 cpm power decreased in the group sham fed unappetizing food. This difference was significant (P < 0.05). In conclusion, we have demonstrated that the cephalic-vagal reflex, as measured by power in the 3 cpm frequency region of the EGG, is sensitive to the subjective palatability of the food.