Released August 18, 2008

STILLWATER, Okla. – When thinking about nutrition, food is what comes to mind for most people. However, water is more critical to life than food.

Water makes up about 60 percent of an adult’s body weight, said Janice Hermann, Oklahoma State University Cooperative Extension Service nutrition education specialist.

“All chemical process that occur in the body require water, including digestion, absorption, circulation, excretion, nutrient transportation, metabolic reactions, maintaining blood volume and maintaining body temperature,” Hermann said. “When the body needs water, it sends a message to the brain and the brain triggers the thirst sensation. When the body has too much water, the brain sends a message to the kidneys to get rid of excess water.”

It is important to keep in mind that thirst naturally lags behind water need. However, the thirst mechanism in older adults is not as effective as in younger adults. As a result, older adults usually underestimate how much water they need.

Hermann said that in addition to a less acute thirst mechanist, older adults are at an increased risk for dehydration for other reasons, including body water decreases with age, many medications used by older adults increase water loss, they may self limit fluid intake due to incontinence and decreased mobility to reach fluids.

“Older adults who are dehydrated are more susceptible to urinary tract infections, pneumonia, pressure ulcers, confusion and disorientation,” she said. “Older adults must realize that dehydration can be life threatening. While the body can withstand losing much of its fat and carbohydrate stores, a loss of 5 percent body water can result in heat exhaustion. A 10 percent loss of body water can lead to heat stroke and circulatory collapse.”

Physical symptoms vary with the level of fluid loss. A person will feel thirst, fatigue, weakness, vague discomfort and loss of appetite with a 1 percent to 2 percent fluid loss. A 3 percent to 4 percent fluid loss will result in impaired physical performance, dry mouth, reduced urine, flushed skin, impatience and apathy.

Difficulty concentrating, headache, irritability, sleepiness, impaired temperature regulation and increased respiratory rate are signs of a 5 percent to 6 percent body fluid loss. A 7 percent to 10 percent loss of body water can produce dizziness, spastic muscles, loss of balance, delirium, exhaustion and collapse.

Water is lost through the kidneys in the form of urine, through the skin in the form of sweat, through the lungs as moisture in the breath and the gastrointestinal tract for elimination.

Water is replaced in several ways, including body production; foods such as meats, fruits and vegetables; and through beverages such as milk, juice, coffee, tea, soft drinks and other beverages.

“A general guideline for water intake is 8 to 12 cups total fluid with a 2,000 calories/day diet. This includes not only the beverages you consume, but also the water in the various foods that you eat as well,” Hermann said.

It is recommended that older adults need a minimum of 6 to 8 cups of fluids per day.

Additional fluid intake is needed to replace fluid lost through excessive perspiration in warm, humid conditions.

Plain cool water is best for replacing water that is lost during hot weather or physical activity that lasts less than an hour.

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http://www2.dasnr.okstate.edu/Members/trisha.gedon-40okstate.edu/older-adults-are-at-increased-risk-for-dehydration

Contact: Trisha Gedon, 405-744-3625, trisha.gedon@okstate.edu