Minimal sensitization to repeated capsaicin exposure during consumption of a real food

Prior work in model systems indicates the oral burn evoked by capsaicin, a TRPV1 agonist found in chili peppers, shows substantial sensitization over 10 acute exposures at short intervals. However, this monotonic increase does not match lived experience during eating, so we investigated capsaicin sensitization using a real food. Following orientation to a general Labelled Magnitude Scale (gLMS) and a generalized bipolar Hedonic Scale (gHS), 75 adults received a series of 10 identical chicken tikka masala samples sequentially. Samples were served every 30 s and participants were instructed to completely consume each 15 g sample before rating oral burn and liking. Random coefficient models revealed a curvilinear relationship between repeated exposure and burn. Specifically, with each additional sample consumed, burn increased (p < 0.001), but this trajectory had a negative quadratic coefficient (p = 0.002), indicating burn plateaued with additional exposure. Hedonic trajectories differed from burn intensity, dropping across exposures (p = 0.01). This may reflect a direct effect wherein liking drops as burn increases outside an optimum range, but we cannot rule out the well-known phenomenon of sensory-specific satiety. Here, we partially contradict prior findings from model systems that suggest capsaicin sensitization continues to build monotonically, instead showing that oral burn from a real food has a quadratic trajectory characterized by initial sensitization within the first few trials, followed by a plateau. This discrepancy may relate to locus or size of stimulus field (small loci on the tongue via cotton swab versus whole mouth during naturalistic eating) or tongue movement (static versus dynamic).