title: Flavor-nutrient learning is less rapid with fat than with carbohydrate in rats.
abstract: Flavor-nutrient learning occurs when the post-ingestive consequences of a food are associated with its flavor. As a signal of the food's energy density, flavor-nutrient associations have the potential to contribute to the regulation of meal size. While all calorie sources (fat, carbohydrate, protein, ethanol) can support flavor-nutrient learning, prior research has found that flavor-nutrient associations based on fat may require higher nutrient concentrations and more rigorous experimental protocols than are required to train carbohydrate (cho)-based associations. To further explore potential macronutrient-specific differences in flavor-nutrient learning, the present study compared the time course of acquisition of cho- and fat-based associations. Rats were trained to associate distinctive flavors with high-density (3.2 kcal/mL) and low-density (0.2 kcal/mL) orally-consumed solutions, either fat (corn oil emulsion) or carbohydrate (sucrose). For each nutrient, both within- and between-group designs were used to assess (via two-bottle preference testing) whether flavor-nutrient learning had occurred after 2, 4, or 6 training trial pairs. Rats trained with carbohydrate demonstrated preferential intake of the low-density paired flavor after only 2 training pairs; in contrast, rats trained with fat required 6 training pairs. These findings demonstrate differential rapidity of acquisition flavor-nutrient associations. The longer time course of acquisition of fat-based flavor-nutrient associations may be yet another mechanism by which high-fat foods promote overeating.
authors.affiliation: Department of Psychology, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore MD 21250, USA.
authors.forename: Christina Humphries
authors.initials: CH
authors.lastname: Revelle
authors.forename: Zoe S
authors.initials: ZS
authors.lastname: Warwick
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002755:Choice Behavior / Q000187:drug effects / Q000502:physiology; D003216:Conditioning, Operant / Q000502:physiology*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D005421:Flavoring Agents / Q000494:pharmacology*; D005518:Food Preferences / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005421:Flavoring Agents