Is the water bottle your constant companion, or are you the type that trusts we can do just fine in between hydration opportunities? Does hydration status really matter all that much?
Clearly, dehydration is an unhealthy, dangerous state. Even mild dehydration - loss of just 2 percent of body weight in water - makes us less alert, affects our wellbeing, and of course makes us feel thirsty. But going without water for just a few hours hasn't been studied much up until now.
4 hours without water
A new study, led by David Benton, in the American Journal of Clinical Nutrition, recruited 101 undergraduate students, aged 18-30 years, and put them in a warm (86 °F, 30 °C) room for 4 hours, during which they performed cognitive tests.
Half the students got a 5oz drink of water 90 and 180 minutes into the experiment.
The students were not aware that what was tested was the effect of hydration on cognition - they were told that the experiment was about the effects of heat. The tests, which were repeated 3 times throughout the 4-hour study, included memory recall quizzes -- in which the students were given lists of words, and asked to recall as many as they could remember immediately after, and then again 20 minutes later -- attention tests and subjective mood scores.
Students that didn't drink water forgot more words in both the immediate and delayed memory recall test, and had poorer attention scores. The students who got some water also reported less anxiety at the end of the test.
The 26 men and 24 women who had no water for 4 hours lost on average 0.72 percent body weight, but at 90 minutes into the experiment the participants lost just 0.22 percent body weight, which is very little. Nevertheless, memory was already affected.
Is your kid drinking enough water at school?
This experiment suggests that even small changes in hydration can make a difference. Mood and alertness are the first to be affected when our body needs food and drink, and while mild changes in body fluids certainly don't put us in danger of dropping blood pressure or shutting off our kidneys, proper hydration can help a student to perform at his best. Kids also lose a larger proportion of their water due to their smaller size and higher activity levels. The authors cite a few studies that prove that as a first-grader, a drink can help you think, and that 7-9 year olds that got an additional drink performed better on visual attention tasks.
As the school year starts, giving kids access to good drinking water, and reminding them to take that drink is a really simple way to make sure studying's a little bit easier and happier. Hydration affects mood and if we can buy a little peace of mind with a glass of water lets do it.
By federal law, free drinking water has to be available to students during school meals. In between, kids should have access to plain water throughput the day, but policies change state-to-state and district-to-district.
Does your school have functioning water fountains? Unfortunately, due to old pipes some school fountains have been found to dispense water with unsafe lead levels.
So, as the school and academic year commence, encourage kids to pay attention to hydration, check that they have access to water that has been tested, and set an example by drinking enough yourself.
To a happy and healthy school year!
Dr. Ayala
This is a crosspost of my blog, Healthy Food & Healthy Living.