Frequent spicy food consumption is associated with reduced capsaicin and salty taste sensitivity but unchanged sour taste or intranasal trigeminal sensitivity

The trigeminal and gustatory perceptions interact with each other during food consumption. Long-term repeated exposure to sensory stimuli leads to plasticity of sensory perception. The present study was conducted to test (i) the effect of frequent spicy food consumption on oral and intranasal trigeminal sensitivity, taste perception; and (ii) the effect of capsaicin at recognition threshold concentration on taste perception among individuals with different spicy food consumption frequencies. Seventy female college students were divided into the high frequency (HF; n = 35) and the low frequency (LF; n = 35) spicy consumption groups based on their self-reported spicy food consumption frequency. We assessed the recognition threshold (using a 3-alternative forced choice task) and suprathreshold intensity (on a generalized labeled magnitude scale) for capsaicin, salty and sour tastes, as well as the intranasal trigeminal sensitivity for menthol and mustard oil odors using the odor lateralization task. Sensitivity and intensity for salty and sour tastes were assessed with and without addition of capsaicin at the group-averaged recognition threshold level (1.38 μM). Compared with the LF group, the HF group had decreased sensitivity for capsaicin and salty taste, and decreased perceived irritative intensity of suprathreshold capsaicin. However, there was no difference for sour taste perception or intranasal trigeminal sensitivity between the two groups. The addition of 1.38 μM capsaicin showed no effect on salty or sour taste sensitivity. However, decreased supra-threshold intensity for salty taste was found in the presence of 1.38 μM capsaicin among participants with high frequency of spicy food consumption (the HF group). These findings suggested that long-term habitual spicy food consumption is related to alteration of oral perception of capsaicin and certain taste.