Ice slurry ingestion reduces human brain temperature measured using non-invasive magnetic resonance spectroscopy

We previously reported that ice slurry ingestion reduced forehead skin temperature, thereby potentially reducing brain temperature (T(brain)). Therefore, in the current study, we investigated the effect of ice slurry ingestion on T(brain) using proton magnetic resonance spectroscopy, which is a robust, non-invasive method. Eight male participants ingested 7.5 g/kg of either a thermoneutral drink (37 °C; CON) or ice slurry (−1 °C; ICE) for about 5 min following a 15-min baseline period. Then, participants remained at rest for 30 min. As physiological indices, T(brain), rectal temperature (T(re)), mean skin temperature, nude body mass, and urine specific gravity were measured. Subjective thermal sensation (TS) and thermal comfort (TC) were measured before and after the experiment. T(brain) and T(re) significantly reduced after ingestion of ICE compared with after ingestion of CON, and there was a significant correlation between T(brain) and T(re). The other physiological indices were not significantly different between beverage conditions. TS and TC were significantly lower with ICE than with CON (p < 0.05). These results indicate that ice slurry ingestion can cool the brain, as well as the body’s core.