Key result
Cold water ingestion raises systolic blood pressure by ~6 mmHg during head-up tilt.
Why the study?
Whether drinking a small volume of cold water during orthostatic stress attenuates the fall in systolic blood pressure was unknown.
Does drinking 200 mL of cold water (4 °C) attenuate the fall in systolic blood pressure during 60° head-up tilt compared to body-temperature water (37 °C) or no water in healthy young adults?
RCT (n=19)
Open-label
Randomized crossover
No
Does drinking 200 mL of cold water (4 °C) attenuate the fall in systolic blood pressure during 60° head-up tilt compared to body-temperature water (37 °C) or no water in healthy young adults?
Ingesting a small 200 mL volume of cold water (4 °C) after blood pressure has fallen during orthostatic stress produces a sustained attenuation of systolic blood pressure reduction, higher stroke volume, and lower heart rate in healthy young adults, unlike body-temperature water which only provides a transient pressor effect during swallowing.
Purpose We examined whether drinking a small volume of cold water during orthostatic stress attenuates the fall in systolic blood pressure (SBP). Methods In a randomized crossover study, 19 healthy young adults underwent 15 min of 60° head-up tilt under three conditions on separate days: no water, 200 mL of body-temperature water (37 °C), and 200 mL of cold water (4 °C). Drinking began 5 min after tilting and lasted 1 min. Hemodynamics and tympanic temperature were analyzed using covariate-adjusted linear mixed models with within- and between-condition comparisons. Results During drinking, SBP increased from pre-drinking values by 9.54 mmHg (95% confidence interval [CI] 5.58 to 13.50) with body-temperature water and 14.70 mmHg (10.74 to 18.66) with cold water. After cold water ingestion, SBP remained higher by 5.95 mmHg (95% CI 1.99 to 9.91) over the first 4 min and 4.84 mmHg (0.88 to 8.80) over the subsequent 5 min. No clear post-drinking increases occurred with body-temperature water. SBP was higher with cold water than with both other conditions during the first 4 min after drinking, and higher than with body-temperature water during the subsequent 5 min. After cold water ingestion, stroke volume was higher and heart rate lower than before drinking, and tympanic temperature declined between the two post-drinking periods. Conclusion Drinking 200 mL of cold water after blood pressure had fallen attenuated the reduction in SBP during continued orthostatic stress in healthy young adults.
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Kubota et al. (2026) conducted an RCT in Orthostatic stress during head-up tilt (n=19). Cold water ingestion (4 °C) vs. Body-temperature water (37 °C, 200 mL) and no water was evaluated on Change in systolic blood pressure (SBP) from pre-drinking tilt (HUT1) over the first 4 minutes after cold water ingestion (HUT2) (MD 5.95 mmHg, 95% CI 1.99 to 9.91).
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