by Brett Iimura and Iona Macnab

For adults, almost nothing beats an icy cold glass of water for quenching your thirst on another sweltering day in Tokyo’s summer. We are encouraged to drink several glasses a day to keep our bodies healthy and our system in balance, but in fact, too much water can be dangerous, especially for babies.

Research has shown that exclusively breastfed babies do not need any additional water in the summer. Studies have been carried out in many of the hottest climates of the world, looking at the babies’ body temperature and kidney function. Breast milk is 88 percent water and low in solutes, so babies do not have as great a need for water as older children and adults. Water supplementation can also introduce pathogens to the baby, and increases the risk of diarrhea, even in developed countries, which can rapidly lead to dehydration in babies. In many cultures the practice of giving water, soups, juices, and teas to young babies is deeply rooted. Some mothers even put soda in their baby’s bottles!

According to the World Health Organization’s Global Strategy for Infant and Young Child Feeding (2003), infants should be exclusively breastfed for the first six months of life to achieve optimal growth, development, and health. Thereafter, to meet their evolving nutritional requirements, infants should receive nutritionally adequate and safe complementary foods, while continuing to breastfeed for up to two years or more. Any additional fluids can increase the risk of allergies and fill up a young baby’s tummy without providing nutrients, meaning she will be able to drink less breastmilk, giving her less of what she really needs to be strong and healthy. Studies show that water supplementation before the age of six months can reduce breastmilk intake by up to 11 percent. If you think your baby is thirsty, just offer her an extra breastfeed.

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Too much water in babies can lead to ‘oral water intoxication.’ This can occur in infants who drink several bottles of water a day or infant formula that is too diluted. If the amount of fluid exceeds the baby’s kidneys’ ability to excrete the excess water, a serious condition in which water dilutes the baby’s normal sodium levels develops. This can lead to a serious electrolyte imbalance, causing seizures, coma, brain damage, and even death. For more information on water intoxication see www.stlouischildrens. org/content/healthinfo/WaterIntoxicationinInfants.htm.

In older children, additional fluids will be an important part of their diet Columbia International School during the summer, but remember that they can get fluids from summer fruits like watermelon and peaches, and vegetables like cucumber and celery, as well as from drinking clean water. Even the water content of cooked pasta and rice is between 65 and 90 percent, and fruits and vegetables are at least 70 percent water, so not all water requirements need to be from drinks. The water requirements for each individual are determined by metabolism, environment, and activity level, and can vary greatly from day to day.

Children are at increased risk for dehydration because they have a higher body surface to mass ratio than adults, and their bodies do not cool down as efficiently as adults’ do. A higher percentage of an infant’s body weight is water. An infant’s fluid exchange rate is also seven times greater than that of an adult, and their metabolic rate is two times greater relative to their body weight. As a result, an infant can dehydrate very rapidly. This is exacerbated by the fact that children are not at liberty to eat and drink as are adults, but are dependent upon their caregivers to meet their fluid needs. Children also spend more time doing physical activity in the sun than adults do. Water and sports rehydrating drinks like Pocari Sweat can be helpful in older children, but if you think your baby or young child shows signs of serious dehydration, contact your doctor immediately.

Brett Iimura ICCE, mother of two, is the director of the Childbirth Education Center (CEC), serving parents-to-be throughout Japan since 1997. Iona Macnab IBCLC is a lactation consultant in private practice in Tokyo and a mother of three. They have over thirty years of combined experience in Japan, and much experience raising bilingual, bicultural children!