Adding cocoa to sucrose: the effect on cold pain tolerance

The sweet taste of sucrose acts as an analgesic, whereas the taste of a bitter substance decreases pain tolerance. The present experiment explores the analgesic effect of a complex taste and asks how adding cocoa, a substance often associated with sweet foods but that has a bitter taste, to a sucrose solution affects cold pain tolerance. The 24 male participants were exposed to Cold Pressor Tests (CPTs) while holding 1 of 3 tastants in their mouths: water, sucrose, or sucrose with cocoa added. After each CPT, participants rated pain intensity and tastant qualities. Intraoral sucrose increased the amount of time that men were able to leave their hands in cold water, whereas the cocoa solution did not. Solutions did not differ in pleasantness or sweetness, but the cocoa solution was rated as more bitter. Bitterness ratings of cocoa exceeded the ratings of sucrose (corrected for water) by an average of 16.9% (P = 0.02), which, in turn, produced a 30% reduction in the duration of pain tolerance (P = 0.002). These results suggest that the addition of a bitter substance reduces cues to the nutritive value of sucrose that may drive its analgesic effect.