Water as an essential nutriment: the physiological basis of hydration

In his letter, Dr Arnaud (Arnaud and Noakes, 2011) mentions that their study (Szinnai et al., 2005), carried out in healthy young volunteers, showed that an acute dehydration up to a level of 2.6% of body weight did not affect their cognitive-motor function. On the contrary, other authors (Ritz and Berrut, 2005; Shirreffs, 2005) showed that a mild dehydration can lead to a significant impairment in both cognitive function and physical performance. Furthermore, experimental acute dehydration in healthy volunteers, such as reported by Szinnai et al., may not be a valid model for severe chronic dehydration in elderly subjects. Therefore, the concept that severe dehydration affects the function of many systems and is a life-threatening condition is supported by many studies. [PUBLICATION ABSTRACT]