An enzymatic–metabolic sensing axis in taste cells detects glucose-yielding carbohydrates

Carbohydrates strongly motivate eating, yet most are consumed in complex forms that do not immediately release glucose. We show that the oral epithelium contains an adaptive enzymatic-metabolic sensing system that enables rapid evaluation of glucose-yielding carbohydrates before digestion. Two enzymes, maltase glucoamylase and glucokinase, act locally in taste fields to preprocess and metabolically assess complex sugars, biasing ingestive behavior toward energetically favorable foods. This mechanism operates independently of canonical sweet taste receptors and is dynamically regulated by dietary experience and receptor sensitivity. These findings reveal that the mouth actively estimates the energetic value of food prior to ingestion, reshaping our understanding of how nutrient sensing guides dietary choice.