The Museum’s Health Sciences Department is partnering with the University of Colorado Anschutz Medical Campus to publish a monthly series on the Museum blog called “Know Health”. The articles focus on current health topics selected by CU’s medical and graduate students in order to provide both English and Spanish speaking communities with current, accurate information. The posts in the “Know Health” series are edited versions of articles that first appeared in Contrapoder magazine. Thank you to the students at the University of Colorado Anschutz Medical Campus for bringing these stories to life.
(aka Dr. Nicole Garneau, chair and curator, Health Sciences Department)
The Balancing Act of Hydration
By Guest Author, Saskia Bunge Montes
Saskia Bunge Montes is a student in the School of Public Health at the University of Colorado Anschutz Medical Campus.
With over 60% of our bodies composed of water, proper hydration is vital to every aspect of our lives. Water regulates body temperature and is critically important for carrying nutrients and oxygen to cells, aiding digestion, eliminating waste, lubricating joints and protecting body organs and tissues.
By controlling our input through thirst and regulating output through perspiration, breathing or urination, the body achieves homeostasis – keeping our fluids balanced and relatively constant. The mechanisms that control our fluid balance are highly sensitive to change and vary according to a person’s metabolism, activity level, diet, weight, health and even the weather. So, the common belief that every adult needs 8 glasses of water (8 fluid ounces each) per day is easy to remember, but ultimately not true for everyone.
Most of us can regulate our water consumption based on our body’s signals. We have no problem fulfilling this need by drinking water, other beverages, and foods that contain water, like lettuce. When problems related to water homeostasis arise they are usually due to medical conditions such as kidney failure or other disorders that decrease the body’s ability to regulate the input and output of water. However, over hydration – an excess of water in the body – can occur in otherwise healthy adults and can lead to a dangerous condition called hyponatremia, or water intoxication. There is such a thing as drinking too much water!
This condition is more common among athletes who want to ensure that they are adequately hydrated for their workout. Drinking too much water can exceed the kidneys’ threshold for excretion and dilute the sodium levels in your blood. This is a problem because the sodium levels in your tissues remain the same, so the dilution causes an imbalance. In an attempt to achieve homeostasis, water will diffuse into the tissue cells to achieve a balance of sodium levels. This causes the cells to swell, which in turn can cause swollen hands and feet, as well as shortness of breath. In extreme cases, the brain can be affected, leading to disorientation, fainting, seizures and even coma. There have even been reported deaths, including two young women who died after running the Boston Marathon in 2002 due to complications of over hydration. Although these cases are extreme and rare, they do happen.
On the other hand, those who don’t drink enough water can suffer dehydration which reduces the volume of blood, increases sodium concentration and causes water to diffuse out of the tissues to achieve homeostasis. The result is dry mouth and skin, disorientation, thirst and decreased production of sweat and urine. Ultimately, it can lead to organ failure, coma and death.
So, even if we don’t know exactly how much a person should drink every day, the highly sensitive mechanisms that govern homeostasis provide signals, such as thirst when water is needed. This is why, for healthy adults the overall recommendation is to let your body guide your intake of water.