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. 2018 Feb 9;8(1):2757.
doi: 10.1038/s41598-018-21086-6.

Ice Slurry Ingestion Reduces Human Brain Temperature Measured Using Non-Invasive Magnetic Resonance Spectroscopy

Free PMC article

Ice Slurry Ingestion Reduces Human Brain Temperature Measured Using Non-Invasive Magnetic Resonance Spectroscopy

Sumire Onitsuka et al. Sci Rep. .
Free PMC article


We previously reported that ice slurry ingestion reduced forehead skin temperature, thereby potentially reducing brain temperature (Tbrain). Therefore, in the current study, we investigated the effect of ice slurry ingestion on Tbrain 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, Tbrain, rectal temperature (Tre), 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. Tbrain and Tre significantly reduced after ingestion of ICE compared with after ingestion of CON, and there was a significant correlation between Tbrain and Tre. 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.

Conflict of interest statement

The authors declare no competing interests.


Figure 1
Figure 1
Magnetic resonance spectroscopy. (a) Magnetic resonance spectroscopy images of the frontal cortex of interest identified on three-dimensional T1 images. (b) An example of the estimation of brain temperature using chemical shift between water and water-N-acetyl aspartate solution.
Figure 2
Figure 2
Experimental protocol. A recorded value before beverage ingestion was defined as Pre, and the value at the end of beverage ingestion was defined as Post. For brain temperature, the mean temperature of the 15-min baseline period before beverage ingestion was defined as Pre. All physiological measurements are presented in 5-min increments from Post to 30 min (+30).
Figure 3
Figure 3
Changes in temperature over time. Changes in (a) brain temperature, (b) rectal temperature, and (c) mean skin temperature during the experiment. Mean changes in (d) brain temperature and (e) rectal temperature from before and after the experiment. The white rhombus shows CON and the black square shows ICE. Values are expressed as mean ± standard deviation. Significant different between conditions: *p < 0.05; ***p < 0.001. Significantly different than Pre: #p < 0.05; ##p < 0.01.

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