Doubling of water intake increases daytime blood pressure and reduces vertigo in healthy subjects.

We studied the effect of increased water intake on ambulatory blood pressure (BP) in healthy individuals. Blood pressure was recorded after 2 weeks of either regular (RWI) or extra water intake (EWI, an additional 30 ml water/kg body weight per day) in 20 healthy subjects (10 males, 10 females). The extra water intake (RWI: 1.7 ± 0.59 l, EWI: 3.7 ± 0.84 l, respectively, p < 0.0001, i.e., an increase of 2 liters) induced an increase in mean arterial daytime BP from 89.0 ± 5.5 mmHg during RWI to 91.4 ± 6.4 mmHg during the EWI phase (p = 0.005), while night-time BP was unchanged by the intervention. The visual-analogue-scale (VAS, maximum score of 10) score corresponding to the statement "I often experience vertigo" was 3.1 ± 2.6 during RWI and decreased to 2.1 ± 2. 1 during EWI phase (p = 0.008). In conclusion,two liters of extra water intake for 2 weeks significantly increased daytime blood pressure and reduced a sense of vertigo in healthy individuals.