Sweet taste does not modulate pain perception in adult humans

Abstract

Background: It is commonly observed that humans who are in pain or discomfort seek solace in the form of sweet foods and drinks. Sugar is routinely used to comfort neonates undergoing painful procedures, and animal studies have shown that sucrose increases the time to withdrawal from painful stimuli. However, there are no published studies examining the effects of sweet substances on heat pain thresholds and percept in adult humans. Methods: Healthy adult volunteers (n=27, aged 18-48 years) were recruited to a controlled, double-blind, randomised, cross-over study to characterise the effect of tasting solutions of equivalent sweetness (10% sucrose and 0.016% sucralose) on warm detection and heat pain thresholds and the percept ratings of painfully hot stimuli. The effect of anticipation of a sweet taste on heat pain threshold was also assessed. Results: Tasting either sucrose or sucralose had no significant effect on the percept of an individually titrated hot stimulus (54.5±4.2 and 54.9±3.2 vs 53.2±3.5 for water, 0-100 visual analogue scale), on the warm detection or heat pain threshold (43.3±0.8, 43.2±0.8 vs 43.0±0.8°C). Anticipation of a sweet substance similarly did not affect heat pain thresholds. Conclusions: Sucrose and sucralose solutions had no analgesic effect when assessed using heat detection thresholds and percept ratings of painfully hot stimuli despite being perceived as sweeter and more pleasant than water. These findings are in contrast to results reported from previous animal studies in which thermal analgesia from sweet solutions is robust. Given the ubiquitous availability of sugar rich drinks in the modern environment, the lack of observable effect may be due to an insufficient hedonic value of the test solutions when compared to the experience of a laboratory rodent. Alternatively, sweet tastes may have a specific effect on pain tolerance rather than the threshold and acute percept measures assayed in this study.

Pain, Smell, and Taste in Adults: A Narrative Review of Multisensory Perception and Interaction

“…Bitter and sweet tastes were found to have no effect on the pain threshold measured with thermal stimulation [58]. Recent studies using electrical stimulation have reported no change in the pain threshold after the administration of sweet and bitter substances [46]; similarly, no change in pain threshold was recorded after heat thermal stimulation and the administration of sweet substances [60].…”

“…The results of experimental studies on pain threshold and tolerance in pain-taste interaction are inconsistent, although the majority of studies reported at least an effect on one of those measures [49, 50, 52-56, 59, 61]. Some studies reported a gender effect, with an effect of taste on the pain threshold and/or pain tolerance in men [53][54][55][56]59] but no effect on the pain threshold in women [49,51,60]. One study explored gender differences by means of the CPT and found an effect of sweet substances on the pain threshold but not on pain tolerance [56].…”

“…Differences in the procedures may explain differences in the results: the temperature at which the CPT was conducted (range 0-2°C to 10°C) or the experimental design (some experiments performed on different days, others all in one session). Only a few studies used different methods [46,48,49,58,60,61].…”

Smell and taste dissociations in the modulation of tonic pain perception induced by a capsaicin cream application

“…Besides, a very recent study on human adults reported that neither sucrose nor sucralose solution had significant effect on the thermal pain perception, although being perceived as sweeter and more pleasant than water (Mooney, Davies, & Pickering, 2020). The authors conclude that a possible explanation is that the sweet experimental solutions probably lacked a sufficient hedonic value for the subjects recruited for the study whereas a sweet drink or chocolate, more pleasant and more complex given the multi‐sensory stimulation, might have more influence.…”

Shifting the Balance: How Top-Down and Bottom-Up Input Modulate Pain via the Rostral Ventromedial Medulla

“…Interestingly, there was a recent report that consumption of a sweet drink did not lead to hypoalgesia in adult humans, although sucrose is reported to ease pain in infants ( 76 ). These authors suggest that the lack of effect in adults may be because of the relative ease of access to sweets in modern society, reducing the hedonic impact of the manipulation.…”