Autism, Water, and Constipation
Home » Treating Autism » Autism, Water, and Constipation facebook

 This editorial also appeared in the Spring 2016 issue of ARI's Autism Research Review International newsletter.

Kelly M. Barnhill, MBA, CN, CCN, The Johnson Center for Child Health and Development, Austin, TX
Harland Winter, M.D., Harvard Medical School, MassGeneral Hospital for Children, Boston, MA

The parents of most children whom we serve within our clinic report that their children have some gastrointestinal symptoms and concerns.  The most common issues that parents raise are constipation, diarrhea, abdominal distention, and pain.  Parents also note several behaviors that may or may not be related to gastrointestinal health, including self-injurious behaviors (slapping or hitting the chest, for example), posturing (such as bending over an arm chair or table edge), and hyperactivity prior to a bowel movement.  These behaviors should trigger concerns about an underlying gastrointestinal problem.  To address the patient’s overall health status and assess the impact of nutritional status, a full evaluation is essential.  Much attention is given to nutrient intake—protein, fat, carbohydrate—but other components of the diet are also relevant.

One of the most underestimated and misunderstood (and easiest to remedy, frankly) deficits in our children’s (and our own) diets is water and fluid intake.  Water accounts for almost 60% of body weight in children (over 75% in infants less than one year of age), and comprises 77-78% of brain volume (McIlwain and Bachelard, 1985). Simply put, water is foundational nutrition and we need to take adequate intake seriously.  Bodily functions rely on water, and being well hydrated is essential for overall health.  Water helps maintain constant body temperature and maintains appropriate blood volume. Water carries nutrients (and oxygen) to cells and also removes waste products.  We have two organs in our bodies that are designed to preserve water.  The kidneys pull water from the urine that is filtered from the blood and return it to the circulation.  The colon’s main role is to reabsorb water.  If we are dehydrated, colonic motility slows down so that more water can be absorbed.  This results in not only a decreased number of bowel movements, but also stools that are harder, more dense, and drier.  For many children with constipation, merely increasing their intake of water significantly helps the problem.

The first question at hand is just how much water is recommended or required for pediatric patients. While we have solid information on most nutrients, recommendations for water intake are lacking.   Research is limited and the few formal guidelines for pediatric water intake can provide conflicting information.  A 2015 study by researchers at Harvard University (Kenney et al., 2015) indicates that the majority of school-age children in the United States were dehydrated to some extent.  Also compounding the issue of assessing both the need for water and hydration status is the body’s ability to adapt to a variety of hydration levels – so we can and do adjust to a dehydrated state and still manage to function.  But there are consequences to constant dehydration.  Research indicates that constipation and cognitive function are two key impacts of this chronic state (Arnaud, 2003; Bar-David, Y, 2005; Fadda R et al., 2008; Gisolfi and Lamb, 1989; Manz & Wentz, 2005; Popkin et al., 2010; Schroeder et al., 2002; Young et al., 1998). For pediatric patients in particular, the data support the belief that dehydration may impact mood, focus, attention, ability to learn, and fatigue levels.

The Institute of Medicine  (IOM) of the National Academy of Science issued Dietary Reference Intakes (DRIs) for the US population in 2005.  These recommendations are based on water intake assessments alone, and they did not include any assessment for hydration status.  This is largely because we have no accepted research or clinical measurements for accurately determining hydration status. DRIs for water intake range from 1.7 to 3.3 liters of water daily for children 4-18.  Children living in hot or dry environments (such as in the winter), or children who exercise and lose water by sweating, may require much more water.  Specific intake recommendations based on age, size, and sex can be found below. 

Most families are shocked by the volume of water intake recommended each day, and many indicate that their children consume much lower amounts.  To put this in perspective, over 40% of Americans do not consume adequate water, and over 25% of US children consume no water whatsoever! (Drewnowski et al., 2013).  While it is true that water content of foods also contributes to total daily intake, our experience is that the children we serve eat few high water content foods such as  fruits and vegetables, so intake from those sources is negligible as well.

In our clinic, we recommend 1 oz of water per pound of body weight per day.  This is an easy calculation for most parents, and equates roughly to the overall DRI recommendations published by the IOM.  Some clinicians encourage 6-8 glasses (cups) of water each day for children up to adolescence, and then make additional recommendations based on age, size, and activity level. 

The next question we face is how to get a child to consume more water.  Two basic answers: make it available and make it appealing.  Water has a lot of competition from juices and sodas and other sweet drinks, so de-emphasizing (or eliminating) those attractive nuisances is a good start in the correct direction. 

These are the suggestions we share with our clients on a daily basis:

  • First and foremost, don’t keep things in your home that you don’t want your children to drink.
  • Teach water consumption from a behavioral perspective as you remove the juice and soda or other preferred beverages.
  • Make water available to your children at all times.  Place a glass or bottle of water next the child’s bed every night.  Remind them in the morning as soon as they awaken to drink the water.  They will be thirsty after an overnight fast and are more likely to drink all the water.  Speak to the school about allowing your child to drink water during school by having a bottle of water on the desk. 
  • Help your child choose fun water bottles.  Look for something that is stainless steel or wrapped glassware, not plastic.  Decorate and personalize it for your child.  If necessary choose multiple bottles for home, school, and afterschool activities.  Encourage your child to keep that bottle with them (and drink) at all times – build in a reward system if necessary.
  • Serve water with all meals – nothing else.  The constant exposure to water as the option will go a long way in reinforcing its acceptance and consumption.
  • Enhance the flavor of the water to make it fun.  Try citrus fruits, berries, and cucumber in water for subtle flavors.  Consider sparkling mineral waters with added flavor in this fashion as well for meals or other special treats. 
  • Finally, remember foods can be rich in water status, too.  Encourage consumption of healthy fruits, vegetables, soups, and broths as a form of water intake. 




Arnaud MJ. Mild dehydration: a risk factor of constipation? Eur J Clin Nutr. 2003;57:S88–S95.

Bar-David Y, Urkin J, Kozminsky E. The effect of voluntary dehydration on cognitive functions of elementary school children. Acta Paediatr. 2005;94:1667–1673. 

Drewnowski A, Rehm C, Constant F. Water and beverage consumption among adults in the United States: cross-sectional study using data from NHANES 2005–201, BMC Public 2013, 13:1068 DOI: 10.1186/1471-2458-13-1068.

Fadda R, Rapinett G, Grathwohl D, Parisi M, Fanari R, Schmitt J. International Society for Developmental Psychobiology; 2008. Washington, DC: 2008. The benefits of drinking supplementary water at school on cognitive performance in children.

Gisolfi C, Lamb DR, editors. Temperature regulation during exercise in children and aolescents.  Youth, exercise, and sport: Symposium: Papers and discussions; 1989; Indianapolis: Benchmark; pp. 335–367.

Kenney E, Long MW, Cradock AL, and Gortmaker SL.  Prevalence of Inadequate Hydration Among US Children and Disparities by Gender and Race/Ethnicity: National Health and Nutrition Examination Survey, 2009–2012. American Journal of Public Health: August 2015, Vol. 105, No. 8, pp. e113-e118. doi: 10.2105/AJPH.2015.30257

Manz F and Wentz A.  The importance of good hydration for the prevention of chronic diseases. Nutr Rev. 2005;63:S2–5 Nutr Rev. 2005 Jun;63(6 Pt 2):S2-5

McIlain H and Bachelard HS, Biochemistry and the Central Nervous System, Edinburgh: Churchill Livingstone, 1985.

Popkin BM, D’Anci KE, and Rosenberg IH.  Water, Hydration and Health. Nutrition Reviews, 68(8), 439–458. (2010).

Schroeder C, Bush VE, Norcliffe LJ, et al. Water drinking acutely improves orthostatic tolerance in healthy subjects. Circulation. 2002;106:2806–2811

Young RJ, Beerman LE, Vanderhoof JA. Increasing oral fluids in chronic constipation in children. Gastroenterol Nurs. 1998;21:156–161