The importance of hydration in overall wellbeing cannot be overstated. Without enough fluid in the body, essential functions such as circulation and nutrient delivery to organs are compromised, leading to less efficient performance. This is especially true for athletes and the military, who can lose up to 10% of their body weight due to sweat loss during challenging events. Even mild dehydration of 2% can lead to a decrease in physical performance.
The application of oral rehydration therapy has been hailed as one of the major public health advances of the past century. Adequate hydration is essential for physical activity and spending time outdoors, especially in hot weather. Reintroducing fluids under conditions of mild dehydration can reverse cognitive deficits induced by dehydration. However, the mechanism of the effects of mild dehydration on mental performance is not yet fully understood. Heat stress may play a critical role in the effects of dehydration on cognitive performance. Good hydration is also vital for overall health and wellbeing, impacting everything from digestion to cognitive function.
Nutrition and public health experts are still working to understand the highly sensitive set of neurophysiological adaptations and adjustments that occur when a wide range of fluids are ingested to protect the body's hydration and osmolarity. Finally, there is strong evidence that good hydration reduces the risk of urolithiasis (see table 2 for test categories).