BITTER TASTE RECEPTOR AGONIST AFFECTS FOOD INTAKEIN HEALTHY SUBJECTS

INTRODUCTION: Bitter taste receptors (T2R) are expressed throughout the digestive tract and it is suggested that might be involved in several gastrointestinal functions. Nevertheless, their role is still unknown. Data on animals have suggested that bitter taste agonists are involved in the control of food intake, but no data are available in humans. AIMS & METHODS: Our aim is to assess whether bitter agonists influence satiation and food intake in healthy subjects. Thirteen healthy subjects (5 males, age 27±8 years, BMI 24±6) were recruited. A capsule containing either placebo, or 18 mg of quinine hydrochloride was administered in a double blind fashion to each subject. After 45 min, all subjects underwent an ad libitum test meal using a standardized meal composed by white bread, cheese and meat cream (89 kcal each portion, with the following composition 50% carbohydrate, 31% fat, 19% protein). The subjects were allowed to eat until they reach the maximum satiation (scored on a visual analogue scale). The amount of kilocalories, the test duration, the level of satiation and all gastrointestinal sensations were scored before and at the end of the test. Data (mean ± SD) were compared by using paired t test. RESULTS: Subjects did not experience any bitter sensation and no adverse effects or gastrointestinal sensations were found after administration of quinine hydrochloride or placebo. The amount of calories ingested was significantly lower when subjects received quinine hydrochloride than placebo (541±180 vs. 610±246 kcal; p = 0.03), similarly the number of ingested sandwiches was reduced (6±1 vs. 7±1; p = 0.03). Conversely, as compared to placebo, quinine hydrochloride did not affect the time to reach the maximum satiety (15±4 vs. 16±6 min; p>0.05), nor the intensity of satiation (80±10 vs. 80±10 mm; p>0.05). CONCLUSION: Administration of a bitter compound is able to significantly reduce caloric intake in an ad libitum test meal. As quinine hydrochloride does affect kcal intake without affecting the time to reach the maximum satiation, we hypothesize that quinine hydrochloride likely decreases the kcal intake by affecting the rate of meal portions consumption. Evaluation of gut hormones kinetics and studies with other bitter taste receptor agonists are needed to establish the role of gastrointestinal taste receptor in the control of food intake