Water + Electrolytes: How They Prevent Dehydration
Intense work or exercise in the heat and serious illness can quickly lead to dehydration. Drinking lots of fluid with electrolytes to prevent dehydration. Here’s what you need to know about water, electrolytes, and why you shouldn’t reach for those calorie-dense, sugary-sweet sports drinks to meet your hydration needs.
Dehydration. You may have read or heard that if you’re working or exercising outdoors in hot temperatures or experiencing illness (such as vomiting and/or diarrhea), you need to stay hydrated and that the simplest solution is to drink plenty of water or an electrolyte-fortified beverage such as Gatorade®. Despite all of the attention focused on the dangers of dehydration, many people are unaware of this all-too-common condition, which can be fatal if one doesn’t recognize the signs.
To shed some light on the issue and clear up some common misunderstandings and misconceptions, this article explains why water is so important, what dehydration is, who’s at risk, and the three stages of dehydration. In addition, it discusses electrolytes, explaining what they are and how they, when coupled with fluid replacement, can treat and prevent dehydration. Finally, this article covers the issue of sports drinks. Despite their popularity amongst certain groups, sports drinks are a poor choice to stay hydrated. This article presents the limitations of many electrolyte-fortified beverages and why they fall short in meeting many people’s hydration needs.
Water: The Most Important Nutrient
Water is the most important nutrient for your body. On average, the human body is 60 percent water by weight, depending on certain factors such as age,gender,and bodyweight.1 The average 70kilogram(kg)(154lb.) man is made up of 42 liters (l) ( or ~11 gallons) of water while the average 55-kg (121 lb.) adult female is made up of 27.5 l (~7.2 gallons) of water. 1
Within the body, water is divided between two major fluid compartments—40 to 50 percent of total body water is contained within the cells, called intracellular fluid; 50 to 60 percent is outside the cells (extracellular fluid).
So, why is water so important? It performs numerous important biological functions in the body. First, at the cellular level, it provides structural firmness.1 Second, water makes up blood, lymph, gastric secretions, and urine. It helps lubricate our joints (synovial fluid), which allows bones to move freely against each other.2
It also forms blood plasma, which transports oxygen, glucose, and amino acids to active muscle and tissue while carrying away carbon dioxide and lactic acid. During exercise, muscles produce lactic acid (plus other acids), and too much lactic acid can impair muscle contractility and performance. Third, water helps maintain core body temperature (thermoregulation). Your body uses water as a cooling mechanism (through sweating) to adequately control its temperature. Even in moderately warm weather, significant amounts of water are lost through sweat.1 Under more arduous training conditions, it’s estimated that sweat losses in endurance athletes exercising in heat and humidity can be nearly 3 liters per hour.1
Even a mild deficit of water can have a substantial impact on well-being, exercise performance, and attentiveness. Defined, dehydration is the loss of body water and important ions (blood salts like potassium and magnesium). It simply means your body doesn’t have as much water and electrolytes as it should have, which interferes with normal body processes.
It’s easy to become dehydrated, and you don’t have to run a marathon to become dehydrated. Each day you lose approximately two to two-and-a-half cups (450 to 600 ml) of water just going about your usual activities, so it is important to replace fluid losses throughout the day. Coffee, tea, and sodas are not an ideal choice. These beverages have a diuretic effect (i.e., trigger water loss) and actually increase your daily fluid requirement.
The current RDA for water for adults at rest under average conditions of environmental exposure is 1 ml/kcal of energy expenditure.3 For women, this amount would equal 2.2 l/day; for men, 2.9 l/day.3
Who’s At Risk?
Any individual can become dehydrated from the following conditions:
- Excessive sweating (e.g., endurance exercise, working outdoors, etc.)
- Vomiting and/or diarrhea
- Excessive urine output (e.g., uncontrolled diabetes, diuretic medications).
Infants, children, pregnant and breastfeeding women, those experiencing illness, and elderly adults have increased needs for water. Infants and children, because of their smaller size and weight, can quickly become dangerously dehydrated if they’re experiencing vomiting, diarrhea, fever, and refuse to eat or drink anything.
Excessive vomiting and diarrhea (lasting longer than 24 hours) is a cause for concern and is a risk factor for dehydration. Usually, the best way to treat it is to increase fluid intake to replace fluids lost through diarrhea/vomiting. In addition, one can also add a rehydration solution, which can be sipped on every two or three minutes. If, however, a baby or adult is showing signs of dehydration (see below), one should seek medical attention immediately.
Elderly adults are another group at risk for dehydration because the thirst desire is reduced as people age. It’s imperative that elderly adults (especially those who live in hot climates and/or who do not air-conditioning) drink plenty of fluids before they become thirsty.
There are three classifications of dehydration: mild, moderate, and severe with each classification based on the amount of fluid lost from the body and not replaced.
In fact, on a hot humid day, an active person can become dehydrated in just 15 minutes. So, how do you avoid getting dehydrated? Well, here are two specific clues:
- Get enough water
- Consume your minerals: sodium, potassium, chloride, calcium, and magnesium
How to Monitor Your Hydration Status
Thirst is a signal that your body needs fluid; however, it’s a poor indicator of your body’s fluid needs because you can lose two percent of your body weight before you feel thirsty.
A better way to gauge your hydration status is to monitor the output and color of your urine. A well-hydrated individual should void 1,000 to 1,500 ml/day, and urine color should be no darker than a pale yellow color.1 If your urine is darker, it is a sign you are dehydrated, and you need to increase your fluid intake.
Dehydration’s Effect on Exercise Performance
Those who work exercise in intense temperatures need to stay hydrated. Athletes should rely on urine output and color or checking their body weight both before and after each exercise session or event to gauge water losses. Ideally, athletes should replace approximately 1 liter of water per kg of weight lost (or ~2 cups/lb).5
Even mild water losses can significantly impede performance. For every one percent of body weight lost, blood volume decreases by 2.5 percent, muscle water decreases by one percent, and the body’s core temperature can increase 0.4 to 0.5° C.7 Changes in blood volume during prolonged exercise impair the body’s ability to deliver oxygen and key nutrients to active muscles, organs, and glands and negatively affect thermoregulation (the body’s ability to regulate core body temperature) by diminishing the body’s ability to expel heat. Losses of three percent are associated with physiological changes, such as decreased blood volume, decreased urine output, diminished performance, and decreased endurance, while losses of nine to twelve percent are fatal.1,7
Minerals – The Spice of Life and an Essential Consideration for Dehydration Treatment
|Sodium||Salt— plain and simple; That is why after sweating you crave salty food.|
|Potassium||Most Americans don’t get enough. The average intake is only half as much as sodium. A healthful intake is 5 times more potassium, than sodium, which is easily obtained by eating a more vegetable and fruit-based diet.|
|Chloride||The mate to both sodium (NaCl) and potassium (KCl), it is essential to keep these items in proper balance.|
|Calcium||This mineral is essential for proper cardiac and muscle function; if too low, one can get muscle cramps.|
|Magnesium||When low, muscle spasms can occur. This mineral is crucial for maintaining a healthy airflow and helping to keep blood pressure balanced.|
|Trace Minerals||The forgotten minerals; just because they are trace and small, they are lost also when one gets dehydrated. Replacing them as well can help maintain overall health and optimal functioning and performance.|
If you are athletically inclined, avoiding dehydration takes on additional significance.
Not only are you at a higher risk, dehydration can really decrease your performance and endurance, thus dulling your performance edge.
There are two basic levels of dehydration that might be treated at home. It is important to remember dehydration can be serious. Here are some signs of dehydration and the level of related severity:
Frequent Signs of Dehydration*
Mild – (Safe to treat at home as long as it doesn’t worsen)
- Dry Lips
- Inside of mouth slightly dry
Moderate – (Children under 12 should see a physician immediately)
- Very dry mouth
- Eyes sunken
- Fontanelles sunken (The soft spots on infants’ heads)
- Tenting (Pinch and lift skin slightly – it doesn’t bounce back readily)
Severe – (This requires hospitalization to rapidly reverse the dehydration via IV theraphy)
- Rapid and a weak pulse (Often over 100 beats per minute)
- Cold hands and feet
- Breathing is rapid
- Lips may be blue
- Person may be lethargic, confused, or apathetic
*When in doubt get medical attention, it is always important to be cautious.
Though the symptoms described above seem ominous, the important thing to remember is that these symptoms occur when dehydration is allowed to occur and is not treated in a rapid fashion. Remembering that the very young and older adults are more susceptible to suffering from dehydration and a more rapid and serious progression of symptoms requiring even more close attention, here are a few points of review that are helpful tips to remember:
Practical Tips to Avoid Dehydration:
- Drink plenty of fluids—consume 8 glasses of 8 ounces of water daily
- Sports drinks can provide carbohydrates, fluid and minerals
- Limit or avoid caffeinated beverages and alcohol—they both increase dehydration
- Outside clothing on warm days should be light, absorbable, and loose-fitting
- Avoid carbonated beverages that can bloat and give sense of fullness, limiting fluid intake
- Use sunblock, staycool, and seek the protection of shade whenever possible
- Taylor PN, Wolinsky, I., Klimis DJ (1999). Water in Exercise and Sport in Macroelements, Water, and Electrolytes, , JA Driskell and Wolinsky I, Eds.,CRC Press, Boca Raton, FL: chap.5.
- Christian JL and Greger JL (1994). In Nutrition for Living, 4th ed., Benjamin/Cummings, Redwood City, CA: chap.4.
- National Research Council (1989). Water and Electrolytes, In Recommended Dietary Allowances, 10th ed., National Academy of Sciences, Washington, D.C., chap. 11.
- Meletis, CM (2002). Dehydration: An Imbalance of Water and Electrolytes. Ogden, UT: By license to Mineral Resources International.
- Clark, N (1997). In Nancy Clark’s Sports Nutrition Guidebook, 2nd ed., Human Kinetics, Champaign, IL, chap. 9.
- Hultman E, Harris RC, Spriet LL. (1994). Work and exercise, In Modern Nutrition in Health and Disease, 8th ed., Shilds ME, Olson JA, and Shike M., Eds., Lea & Febiger, Philadelphia, PA: chap. 42.
- Wilmore JH and Costill DL (1994). In Physiology of Sport and Exercise, Human Kinetics, Champaign, IL:chap. 15.
- Seelig, MS(2001). Human Needs for Magnesium are Not Met by Most People. Ogden, UT: Mineral Resources International.
- von Fraunhofer AJ, Rogers MM. Effects of sports drinks and other beverages on dental enamel. General Dentistry
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