Khan NA, Westfall DR, Jones AR, et al. - Since insufficient hydration prevails in a large proportion of US children, researchers determined how urinary markers of hydration and cognition among preadolescents are influenced by water intake. They used a 3-intervention crossover design. Participants were individuals 9- to 11-y-olds [n = 75 (43 males, 32 females); 58.2 ± 28.5 BMI percentile]. The interventions used involved either maintenance of water intake [ad libitum (AL)] or intake of high (2.5 L/d) or low (0.5 L/d) water for 4 d. As per the findings, hydration varied significantly across all 3 interventions. During the low intervention vs during AL, urine color was greater, and both were greater than during the high intervention. Overall, improvement in urinary markers of hydration was seen following the water intervention. Also, the selective benefits of the intervention were noted during task switching. Furthermore, greater habitual hydration and water intake had selective benefits on children's cognitive flexibility.