Diet and cephalic phase insulin responses.

Cephalic phase digestive responses may be particularly critical in determining our various reactions to different diets, since these responses are the first physiological adjustments to food. The potential importance of the cephalic responses is also underscored by the fact that many of the most important food attributes for humans--color, appearance, flavor, aroma, and texture--can influence the individual's gastrointestinal physiology solely by affecting these early metabolic responses. The present survey examines in some detail the data available for one of the responses, the cephalic phase insulin response. Specific shortcomings of the existing analyses are discussed. In addition, given the possible significance of these reflexes, several suggestions for improvements of experimental protocols are considered, and a summary of major experimental questions is provided.