Monday, June 29, 2009

Drink More Water ... and Drink More Water!

With the Summer Months in full swing, MedFN wants to make sure you have all of the facts about the causes and dangers of dehydration. You might be surprised about some of this too!

Why is Water so Important? (Taken from – March 5, 2008)

More than half of the human body is composed of water, making it essential to maintaining health: adults have approximately 60% body weight in water, infants have approximately 70% water weight, small children have more than adults but less than infants, and the elderly have slightly less than that of the average adult. Water is a component of every tissue, muscle, bone, and cell in the body, although the portion of water may vary according to the location and function in the body. (Grosvenor & Smolin, 2006)

A human can live about eight weeks without food, but only a few days without water. Water is so vital to the body's health and wellbeing that the body uses devices to regulate its consumption and elimination. One such device is the thirst sensation. Thirst sensations are signals from the brain that cause a dry mouth; however, one should not wait until one feels thirsty to drink, because by the time one feels thirsty, water loss can impede performance, particularly in athletes.

Water losses through urination are regulated by the kidneys. The pituitary gland secrets an antidiuretic hormone (ADH) that will cause the kidneys to reabsorb water instead of releasing it into the urine if the ratio of water and dissolved particles (electrolytes, toxins, etc.) are out of balance. ADH can only do so much, if a lot of wastes are in the blood, they must be excreted, which mean water loss. The body does not regulate water loss in sweat, feces, or evaporation (loss through skin and exhalation). (Grosvenor & Smolin, 2006)

Unlike the camel, the human cannot store water in the body for use when water supplies are limited; water is constantly being lost from evaporation and urination, meaning that water must be consumed regularly. The increased production of ketones and urea during weight loss must be eliminated through urination, thus increasing the body's need for water. Physical activity and a diet high in sodium or fiber also increase the body's need for water. (Grosvenor & Smolin, 2006)

Zelman says that most water (80%) is obtained through the liquids consumed, but a significant amount (20%) is derived from foods; the 20% derived from food sources can be surprising, for instance: lettuce is 95% water, broccoli is 91% water, orange juice is 88% water, a carrot is 87% water, and an apple is 84% water. Heat, humidity, illness, weight loss, and physical activity increase the body's needs for fluids. (Zelman, 2006)

The previous recommendation for eight 8-ounce glasses of water per day has been debunked: a study published by the American Journal of Physiology in 2002 says that any liquids consumed can count toward the daily liquid needs and recommends that healthy adults, not regularly performing rigorous activities or living in extreme temperatures, should simply drink when thirsty; and the Institute of Medicine released new recommendations for liquid consumption in 2004 for women to have 91 ounces (over 11 cups) and men 125 ounces (15 cups) per day from fluids and food sources. This means that most women need to drink around nine cups of water or other liquid (the other two cups are derived from food sources) and most men need to drink roughly 12.5 cups per day of water or any other liquid; however, water is the superior choice. (Zelman, 2006)

Water provides many functions in the body that regulate and maintain good health. For instance, water lubricates eyes to wash out debris, and saliva to moisten the mouth during swallowing and chewing of food, reducing complications such as choking. Water also cushions joints from impacts, and is a large constituent of the blood which is responsible for the delivery of nutrients and oxygen as well as the elimination of waste products. Water allows for the dissolution and distribution of glucose and many other valuable nutrients and minerals throughout the body. (Grosvenor & Smolin, 2006)

Water also regulates the body temperature through several processes. When the body's temperature rises, the skin gets a flushed appearance due to the increased blood flow that allows for the release of heat through the release and evaporation of sweat. In cold temperatures, the opposite occurs; blood vessels are constricted to reduce heat loss. (Grosvenor & Smolin, 2006)

When the body does not get the amounts of water it needs, the body becomes dehydrated. The first symptoms of dehydration are thirst, dry eyes, dry mouth, darkened urine, headache, fatigue, and loss of appetite; additional losses alters the ability to think and perform physical tasks. Late stage dehydration symptoms include inability to concentrate, confusion, nausea, and disorientation. Grosvenor & Smolin (2006) warn that, "a loss of about 10 to 20% of body weight as water can be fatal" (p. 286).

At the opposite end of the spectrum, too much water consumption, also known as water toxicity, can dilute electrolytes in the blood. Water toxicity early symptoms are similar to alcohol intoxication and dehydration symptoms and include disorientation, nausea, muscle cramps, confusion, and slurred speech. Late stage water toxicity can cause coma, seizure, and death. Drinking water that also contains small amounts of sodium and sugar when exercising for one hour or longer can prevent water toxicity. (Grosvenor & Smolin, 2006)

Sodium, potassium, and chloride are electrolytes that conduct electrical currents to transmit nerve impulses, muscle contraction, regulate fluid levels, and maintain the acid/base balances. Sodium and potassium are responsible for major positive extracellular ion, nerve transmission, muscle contraction, and fluid balances. Chloride is responsible for major negative extracellular ion and fluid balance. Sodium is derived primarily from table salt and processed foods; muscle cramps can indicate a sodium deficiency. Potassium is derived primarily from fresh fruits and vegetables, whole grains, milk, and meats; a potassium deficiency can cause an irregular heartbeat, fatigue, and muscle cramping. Chloride is derived primarily from table salt and processed foods. A deficiency in chloride is unlikely to happen. The body closely controls and balances these and other electrolytes. (Grosvenor & Smolin, 2006)

The diet consisting primarily of processed foods is high in sodium content but low in potassium which is derived primarily from fresh fruits and vegetables. An excess of potassium can kill you by literally causing the heart to stop beating. An excess of salt contributes to high blood pressure in those individuals who are salt-sensitive and can cause bone loss due to loss of calcium. (Grosvenor & Smolin, 2006)

Alcohol and caffeine can have a tremendous affect on hydration levels. Alcohol blocks the ADH (antidiuretic hormone) activity producing the effects described as a "hangover," but is actually due to Alcohol increases the risk for phosphorus and magnesium deficiencies, high blood pressure, and loss of bone mass. Caffeine, in a manner similar to alcohol, increases urination which increases the risk of dehydration. (Grosvenor & Smolin, 2006)

Maintaining proper hydration is important to one's health and wellbeing. Tips to prevent oneself from becoming dehydrated include: drinking at regular intervals; drinking extra water on hot days and during strenuous physical activity; drink before, during, and after exercise; reduce salt intake by not adding salt during the cooking phase, use spices to flavor foods, limit salty snacking and salty sauces such as soy sauce; and eat more fresh vegetables, fruits, and whole grains. (Grosvenor & Smolin, 2006)


Grosvenor, M. B., & Smolin, L. A. (2006). Nutrition: Everyday choices. New Jersey: John Wiley & Sons, Inc.

Zelman, K. M. (2006). The Wonders of Water. WebMD Feature.