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Keep Your Kids Hydrated

Earlier this year I reported on a small study in college students that suggested that mild to moderate dehydration could affect the brain's cognitive functions, including short-term memory, reasoning, and even mood. Indeed, it's been estimated that most adults in Western cultures are chronically mildly dehydrated. Children are at even more risk of dehydration because their ratio of body surface to mass is so much lower than that of adults.

Researchers in Italy, in collaboration with researchers in Switzerland and Australia, noted the lack of empirical evidence regarding dehydration in children. Certainly, given the evidence in adults, it would seem likely that children would also be chronically dehydrated and that their brains' functions might be affected. Likelihood, however, is not evidence, so they designed a study to test the theory (Appetite 2012;59(3):730-737).

The study was performed in Southern Italy and included 168 school children in 12 classes whose parents provided informed consent for their children to participate. The children were all between 9 and 11 years old and the group was evenly divided between male and female. Each class was randomly assigned to one of two groups.

On two consecutive, moderately warm days, all of the participating children provided urine samples at the start of the school day so that their hydration levels could be measured. One group continued with their ordinary school day, during which, per school policy, they were not permitted to have water or other beverages in their classroom or at their desks. (Of course they had their usual lunches with their usual lunch beverage.)

The second group was provided 1/2 liter of water for each student to have at their desk and to drink freely from. Their teachers were tasked with reminding the children to drink their water (although drinking the water was not required). After lunch the children were given another 1/2 liter of water whenever they finished their first 1/2 liter.

At the end of the school day, both groups completed the same cognitive tests and supplied another urine sample. On the second day of testing the groups switched, so that all of the children experienced one day with water at their desk and one day without.

The researchers could then compare the childrens' hydration levels with their performance on the cognitive tests. Unsurprisingly, they found that children performed better in tests that measured their short-term memory when they were well hydrated. On the other hand, dehydrated children performed better on verbal analogy tests (for example: "Quiet" is to "sound" as "darkness" is to (a) cellar; (b) sunlight; (c) noise; (d) stillness).

What this means for you

Obviously the effects of hydration aren't so simple as More Hydrated = Better Test Scores. What we do know is that adequate water intake is important not just for the brain, but for the whole body. Are your children allowed access to enough water at school? One way to encourage children to drink water instead of sodas might be to allow them to have water at their desks (but not sodas).

First posted: October 10, 2012