Water intake is critical for many body functions, but it’s especially important for optimal brain health. It’s so important that the human body can’t live more than a few days without it. Water makes up to about 60-65% of your child’s total weight (up to 75% for infants). That’s a lot of water!
Children are more likely to become dehydrated than adults because they lose more water through their skin. They also lack awareness of how much fluid they need to consume to stay hydrated. On top of that, they might not take into account all of the physical activity they do that increases their need for water.
Even mild dehydration – as low as a 1% loss of body fluid – can result in mental changes, including restlessness, lack of focus, negative effects on short-term memory, headaches and fatigue. In more severe states, it can lead to dizziness, agitation, restlessness, confusion and lethargy. To top it off, levels of stress hormones coursing through the body increase in states of dehydration, which has been associated with decreased mental function1.
It may not be enough to let your child drink water only when they’re thirsty.
Researchers who studied the effects of hydration on kids at a soccer training camp found most of the children to be dehydrated.2 Despite having unlimited access to drinking water, over 90% of the children remained dehydrated at the end of their soccer training. This finding is serious, because the researchers found that drinking water according to thirst didn’t prevent the children from becoming even more dehydrated.
Other researchers have found that more than two-thirds of kids age 9-11 weren’t properly hydrated by the time they got to school in the morning. They also found that the amount of fluid they consumed at breakfast wasn’t enough to maintain ideal hydration levels throughout the morning.3
Dehydration can have several negative effects on children’s mental function.
The effects of dehydration on children’s mental function was studied in school aged kids.4 Sadly, the researchers found that dehydration seemed to be a common occurrence, and not surprisingly, they found that it had a negative effect on mental function. Different types of tests were used to evaluate concentration, attention, memory, math and language skills, and the researchers noticed a direct link between dehydration and lower levels of achievement.
On a happier note, it seems that even with mild dehydration, children’s mental performance can be improved by having a drink of water.5 One study assessed the effects of drinking water on the mental function of children.6 When the children were given 300 ml (just over a cup) of water to drink, their memory recall was significantly better than how they performed without the additional water. Another study found that children who drank additional water performed better on attention testing compared to children who didn’t drink additional water.7
So, can drinking more water make your kid smarter? Drinking enough water seems to positively impact mental mental performance, but more research is needed before any claims can be made about it increasing IQ. In the meantime, developing healthy hydration habits is still a smart thing to do.
How much water should your child be drinking?
The Institute of Medicine of the National Academies recommends the following drinking water intake for kids8:
- Infants: breast milk is sufficient
- Children 1-3 years: 4 cups a day
- Boys and girls 4-8 years: 5 cups a day
- Girls 9-13 years: 7 cups a day
- Boys 9-13 years: 8 cups a day
- Girls 14-18 years: 8 cups a day
- Boys 14-18 years: 11 cups a day
(1 cup = 250 ml = 8 fluid ounces)
Here are a few tips to encourage kids to drink more water:
- It’s important to keep in mind that total water intake comes from drinking water, other beverages, and foods that contain a lot of water. Offering fruits and veggies that have a high water content such as apples, cabbage, cantaloupe, cherry tomatoes, celery, cucumbers, grapes, pears, sweet peppers, watermelon and zucchini can help to keep kids hydrated. A side of soup with meals can sneak in even more fluids. Every little bit counts.
- Encourage your children to drink water regularly throughout the day and be a good example by drinking it regularly yourself.
- Use fun drinking straws, special drinking cups and colorful water bottles (ideally stainless steel or BPA free to avoid environmental contaminants). Consider letting kids choose their own water bottle to make it more fun to bring a bottle along with them during the day. Encourage them to refill their bottles at school throughout the day.
- To keep water cold in lunch bags, freeze ½ a bottle of water in the freezer overnight, and top it up with cool water in the morning before sending them off for the day.
- During physical activity, kids need more water, especially in hot weather. Encourage an additional half cup of water every 20 minutes during vigorous activity.
- It’s helpful for kids to make drinking water part of their daily routine. Encourage a half to full glass on waking up, offer water with meals, snacks, and when they arrive home from school, and again before they brush their teeth.
- If your child says they aren’t thirsty, encourage them to have three sips of water – most of the time they’ll end up drinking more on their own. If not, you can always offer it again later. Younger kids might need to try water about a dozen times over a two-week period before they start to develop a taste for it. Infuse water with sliced lemons, limes, berries, cucumbers or sprigs of fresh mint. For older kids, you can freeze berries or sliced fruit in ice-cubes, and add these to water for a hint of flavor.
- Consider using a reward system to motivate younger kids. Posting stickers on a daily water log can encourage them to drink more, and help younger kids learn to keep track of how much they’ve had to drink during the day. Do something special to celebrate their new healthy routine – a trip to a water park or lake perhaps?!?
- D’Anci, KE, Constant, F, Rosenberg, IH. (2006). Hydration and Cognitive Function in Children. Nutrition Reviews; 457-464. First published online: 1 October 2006
- Arnaoutis G. et al. 2013. Ad libitum fluid intake does not prevent dehydration in suboptimally hydrated young soccer players during a training session of a summer camp. International Journal of Sport Nutrition and Exercise Metabolism; 23: 245-251.
- Bonnet F et al. (2012). French children start their school day with a hydration deficit. Ann Nutr Metab. 60(4): 257-63.
- Bar-David, Y, Urking, J & Kozminsky E. 2005. The effect of voluntary dehydration on cognitive functions of elementary school children. 94; 1667-1673.
- Edmonds CJ, Jeffes, B. (2009). Does having a drink help you think? 6-7 year-old children show improvements in cognitive performance from baseline to test after having a drink of water. Appetite 53(3): 469-472.
- Benton, D & Burgess, N. (2009). The effect of the consumption of water on the memory and attention of children. Appetite 53(1): 143-146.
- Edmonds, CF, Burford, D. (2009). Should children drink more water? The effects of drinking water on cognition in children. Appetite 52(3): 776-779.
- Institute of Medicine of the National Academies. Dietary Reference Intakes (DRIs) Tables. Recommended Daily Allowance and Adequate Intake Values: Total Water and Macronutrients.