 What is the hydration status of healthy children in the United States? Preventing cellular dehydration is integral to hormonal, immune, neurological, cardiovascular, gastrointestinal, muscle, and skeletal functions. So researchers got urine samples from a group of 9 to 11-year-olds in LA and Manhattan on their way to school to see how they were doing. 50 bucks to pee in a cup, not bad. The study was motivated by recent studies in Israel showing children did not seem to be hydrated enough, but Israel's in a desert. So that's why they repeated the study under cooler and less arid conditions. Yet, U.S. kids did just as bad as the Israeli kids. The urine from nearly two-thirds of the kids was considered too concentrated and indicated that they were dehydrated. Why? They weren't drinking enough water. The record of the kids did not drink water between when they woke up and when they went off to school. But most did eat breakfast, so they must have been drinking something. The problem is that other beverages are not as hydrating. The levels of sodium sugars and amino acids and milk and juice can shrink cells and trigger the release of the hormone that signals dehydration. So what, though? I mean, is there any actual negative impact of mild dehydration on their ability to function at school? Historically, most of the studies on hydration and mental functioning were done on adults under extreme conditions, like having people exercise in 113 degree heat, or giving people powerful diuretics like Lasix and putting them on a treadmill. And most of the studies on hydration and cognitive performance have been performed on military personnel to evaluate soldiers' ability to function in extreme circumstances. It's easy to imagine that a soldier fighting in the desert with a heavy rucksack and a protective suit must be physically and cognitively at their best. It is, however, very difficult to translate this knowledge to normal, real-life circumstances. But three new studies did just that. Simple study. Take a group of school children, randomly allocate them to a drink, a cup of water, or not, and then just give them all a test and see who does better. And the winner was the cup of water group. Conclusion. The results of the present study suggest that even children in a state of mild dehydration, not induced by intentional water deprivation or by heat stress or living in an extreme climate, can benefit from drinking more water and improve their cognitive performance. So, water worked for second and third graders. What about first grade? Same experimental design, but this time, instead of forcing kids in the water group to drink a cup, the water group was just given some water and told to drink as much as they wanted, and again found significant improvement in their performance on various tasks leading to the same conclusion. Even under circumstances of mild dehydration, children's cognitive performance can be improved by having a drink of water. And the latest study that just came out, the largest to date, which really put it all together, they too also found a remarkable proportion of children were in a state of mild voluntary dehydration at the beginning of the school day, found a significant negative correlation between dehydration and, for example, the ability to remember numbers. They offered a randomized group of some water, and those kids on average felt better and performed better. Though dehydration might affect some cognitive abilities more than others, it is an adverse state that might render the school day more challenging for children. Even doctors often apparently fail to realize the connection. A recent study found that healthcare professionals under-recognize the importance of proper hydration for mental health. Who would care enough about the importance of human hydration to even do such a study? The European Hydration Institute found it in part by the Coca-Cola Company. Significant improvement in cognitive performance, but not with Coke and not with Ritalin or some new drug either. Just plain water. Think how much drug companies could make if they could sell sugar pills, but just tell kids to take the fake pill with a glass of water.