K-State Research and Extension News
July 13, 2011
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Fluids Important to Managing Heat, Humidity Safely

MANHATTAN, Kan. – In recent years, reusable water bottles have taken on stylish new looks, but making a fashion statement pales in comparison to the value of the life-saving role fluids play in reducing risks from too much summertime heat and humidity.

Drinking eight to 12 cups of fluid a day is recommended under normal circumstances to replenish essential body fluids, and more is needed as summer temperatures and humidity rise, said Mary Meck Higgins, K-State Research and Extension nutrition specialist.

“We sometimes forget that 55 to 75 percent of the body’s weight is water; the brain is 70 percent water; blood is 82 percent water, and the lungs are nearly 90 percent water,” said Higgins, who noted that water carries nutrients and oxygen to cells; cushions organs, tissue, bones and joints; removes waste; and regulates body temperature.

In high heat, humidity, and times of high activity, such as working outdoors or participating in athletic activities, water is lost through perspiration, which helps cool the body through the evaporation of fluids on the skin.

Exposure to the sun or a sunburn will speed fluid loss, and so will drinking beverages containing caffeine or alcohol, which both act as diuretics, said Higgins, who explained that excessive water loss or dehydration can impair body function and lead to heat exhaustion and/or heat stroke that can be life threatening.

“Fluid replacement is essential, but it’s best to not wait until you’re thirsty,” said Higgins, who added that people often become slightly dehydrated before they become thirsty.

Checking to see if your body is well hydrated is easy, said Higgins, who explained that if urine is pale yellow in color, fluids intake are likely adequate. If urine is dark yellow or appears concentrated, more fluids are needed.

Water is recommended for the majority of the fluid replacement because it is readily absorbed; cool water is preferred because it is absorbed more readily than warm, hot or ice water.

"Other good sources of fluids include milk,100 percent fruit juice, low-sodium vegetable juices and foods that have a high water content, such as melons and other fruits, tomatoes and other vegetables, and soups, smoothies, puddings, gelatin salads and other foods made with milk, fruit juices or broths," the nutrition specialist said.

Beverages that contain caffeine, including coffee, tea and some soft drinks, or alcohol act as a diuretic that speeds fluid loss, so are not recommended as essential fluid replacements, Higgins said, adding that only half of the amounts of these beverages be counted towards total fluid replacement.

Sports beverages may be helpful for athletes who are exercising more than one hour and are in need of lost electrolytes and quick energy, but she recommends diluting them with an equal part of water to help replenish fluids and reduce calories.

Low-fat chocolate milk also can be a good fluid replacement for athletes, said Higgins. She cautioned that sugary sports drinks or carbonated beverages can add unnecessary calories.

Before working in the heat, exercising or participating in athletics, Higgins recommends drinking 14 to 22 ounces of cool water. She also recommended drinking 1-1 1/2 cups of water every 15-20 minutes during exertion, and encourages parents to make sure that children take frequent water breaks (one-half cup after each 15 minutes of activity).

Older adults need to drink fluids, even if they are not thirsty. The ability to sense thirst declines over the years, leaving older people unable to rely on their thirst to prompt them to drink enough fluids.

The ability to regulate body temperature easily also declines with age. So, if a caregiver is thirsty, a dependent older adult, infant or small child probably is, too. Higgins recommended holding a glass of water or other nourishing liquid up to them when offering a drink.

In order to make sure that people who work outdoors, athletes and active children get enough fluids to replenish fluid loss, she suggested weighing before and after an activity and drinking 16-24 ounces of water for each pound lost.

"Parents also are encouraged to monitor their children’s (including infants and toddlers) fluids. Water is recommended for infants who have started on solid foods,” said Higgins. Weighing children before and after play or participation in an athletic event can be helpful in gauging a child’s fluid loss and replacement needed.

In addition to replacing fluids, Higgins recommends wearing a hat with a brim and sunglasses; choosing loose, comfortable clothes that breathe; using sun screen; and taking occasional breaks to help minimize the effects of heat and humidity.

More information about nutrition, health, and managing summer meals and snacks is available at K-State Research and Extension offices throughout the state and online at K-State's Human Nutrition and Rapid Response Center


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Encourage Fluids for Children

MANHATTAN, Kan. – Parents are encouraged to monitor children’s activities and to offer water to replenish fluids frequently, said Mary Meck Higgins, Kansas State University Research and Extension nutrition specialist.

While sunny days can encourage child’s play, children do not always recognize their thirst or realize that they are becoming dehydrated and at risk, said Higgins, who explained that a child’s body size means that he or she will generate more heat relative to their size than adults do. They will also lose more fluids because they have a greater proportion of skin surface in relation to their size.

Offer water frequently, each time a child passes through the kitchen and before, during, and after play, she said.

More information about children’s nutrition and health is available at K-State Research and Extension offices throughout the state and online at K-State's Human Nutrition and Rapid Response Center



K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by: Nancy Peterson
K-State Research & Extension News

Mary Meck Higgins is at 785-532-1671 or mhiggins@ksu.edu