Does a Drink of Water Make Children Smarter?

Michael Greger M.D. FACLM · May 1, 2013 · Volume 13

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Most children don’t drink water from when they wake up to when they go off to school. Interventional trials show this mild state of dehydration may negatively affect scholastic performance.

Discuss

Transcript

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“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 function.”

So, researchers recently got urine samples from a group of 9- to 11-year olds in L.A. 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—an indicator that they were dehydrated. Why? They weren’t drinking enough water. Three-quarters 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 in 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. “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 is easy to imagine that a soldier fighting in the desert with a heavy rucksack and a protective suit must be physically and cognitively at his 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 schoolchildren, randomly allocate them to 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 and 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: “…[E]ven under conditions of mild dehydration, children’s cognitive performance can be improved by having a drink of water.”

In the latest study that just came out, the largest to date, which really put it all together, they too also found that “a remarkable proportion of children were in a state of mild, voluntary dehydration at the beginning of the school day. [They] found a significant negative correlation between dehydration” and, for example, the ability to remember numbers. They offered a randomized group some water, and those kids, on average, felt better and performed better. “…[T]hough 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-recognised 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, founded 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.

Please consider volunteering to help out on the site.

Sources

Acknowledgements

Images thanks to aka Kath via flickr. Thanks to Cipher on PhotoRee, Maxim Fetissenko, PhD, and Laurie-Marie Pisciotta for their Keynote help.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

“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 function.”

So, researchers recently got urine samples from a group of 9- to 11-year olds in L.A. 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—an indicator that they were dehydrated. Why? They weren’t drinking enough water. Three-quarters 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 in 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. “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 is easy to imagine that a soldier fighting in the desert with a heavy rucksack and a protective suit must be physically and cognitively at his 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 schoolchildren, randomly allocate them to 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 and 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: “…[E]ven under conditions of mild dehydration, children’s cognitive performance can be improved by having a drink of water.”

In the latest study that just came out, the largest to date, which really put it all together, they too also found that “a remarkable proportion of children were in a state of mild, voluntary dehydration at the beginning of the school day. [They] found a significant negative correlation between dehydration” and, for example, the ability to remember numbers. They offered a randomized group some water, and those kids, on average, felt better and performed better. “…[T]hough 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-recognised 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, founded 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.

Please consider volunteering to help out on the site.

Images thanks to aka Kath via flickr. Thanks to Cipher on PhotoRee, Maxim Fetissenko, PhD, and Laurie-Marie Pisciotta for their Keynote help.

Doctor's Note

This is one of those groundbreaking findings, like the study on gargling (see, Can Gargling Prevent the Common Cold?) that will likely never see the light of day because there’s no profit motive for promotion. We’re guaranteed to be assailed about all the new drugs and surgical advances, because there’s big business behind getting the word out. But who profits from tap water? Or even broccoli, for that matter?

That’s one of the reasons I created this site—to bring to light all the findings that would otherwise just get buried in medical library basements (or, increasingly, vast private databases). If you find this site useful, please consider making a donation to keep this site alive and kicking.

The water content of plant foods may help explain why those eating plant-based diets are, on average, so slim (see The Ice Diet). See Dietary Guidelines: It’s All Greek to the USDA for a country with the guts to suggest water might be preferable to drinking soda.

Juice and milk may not be as hydrating as water. What about tea? See Is Caffeinated Tea Dehydrating?

More on children’s health in videos such as:

And, check out my associated blog post for further context: Schoolchildren Should Drink More Water.

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