Sensitivity to sweetness correlates to elevated reward brain responses to sweet and high-fat food odors in young healthy volunteers.

Taste sensitivity relates to food preferences and macronutrients intake. The current study investigated whether the neural responses to food odors varied in sensory quality (sweet or non-sweet) and their associations with macronutrient content (high- or low-fat) in young healthy participants varied in sweet taste sensitivity. Thirty-eight participants were assessed for their sensitivity to sucrose solutions using a modified "taste strip" test. They were divided into high sweetness sensitive (HS, n ​= ​15) and low sweetness sensitive (LS, n ​= ​15) groups using the median split approach. Brain responses to four food-related odors (chocolate, peach, peanut, and bread) and one non-food odor (rose) were assessed using functional magnetic resonance imaging (fMRI). Preferences for tastes and macronutrients were measured using a computer-based task. Behavioral results showed that HS group, compared to LS group, had a higher preference for carbohydrate-dominated foods and liking for sweet foods, but a lower liking for protein-dominated foods. The food odors, in comparison to non-food odors, produced greater brain-activations in the gustatory and reward regions. Compared to LS group, the HS group showed a higher level of activation in the frontal inferior operculum in response to sweet vs. savory food odors, and stronger insular activations to high-fat vs. low-fat food odors. In addition, individual sweetness sensitivity was positively associated with activation of the insula in response to chocolate odor, suggesting an overlap of neural responses to food odor with high sugar and fat content. Our findings highlight that high sensitivity to sweetness can be associated with increased preference for carbohydrate-dominated or sweet foods, and elevated brain activations to sweet or high-fat food odors in the areas related to food reward processing.